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Logic, Philosophy & Paradoxes ft. Graham Priest | Know Time #93

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this is a conversation with graham

priest he's a distinguished professor of

philosophy at the City University of New

York and trust me when I say this he's

one of the Giants of philosophical logic

he has written multiple books including

beyond the limits of thought and in

contradiction and has written

extensively on paraconsistent logic and

ditheism in this conversation we discuss

his childhood growing up in post World

War II London

how we got into philosophy we talk about

logic classical logic and non-classical

logic intuitionistic logic and

paraconsistent logic talk about fuzzy

logic and ditheism we also cover the

limits of language and the nature of

contradictions and then we give a quick

teaser into Buddhist and Eastern

philosophy this is no time if you like

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it's no time [Music]

[Music]

the classic book uh Tale of Two Cities

by Charles Dickens begins with this

really popular line it was the best of

times it was the worst of times in

previous interviews when you've

described your childhood and your

teenage years I think this line fits it

perfectly you grew up in post World War

II London in the 1950s which is a rather

Grim decade you've mentioned in previous

interviews that you used to explore bomb

sites with your friends

rationing was the norm of the time but

as it so often happens in periods of

unrest and tragedy it's also a cultural

explosion I personally feel the 50s and

60s and' 70s in in the UK were probably

one of the most rich and productive

areas of British culture the explosion

that you saw in the Music Arts of

literature maybe even architecture

movies was pretty incredible you have

said in a previous interview that it was

a Decades of Youth Rebellion rock music

the pill rejection of oldfashioned

values the anti-establishment

counterculture the hippie movement such

an explosion it was the Decades of The

Beatles Cream lead Zeppelin Rolling

Stone Monty Python glassen the seeds

were starting to get planted for the

madchester phenomenon or the punk

movement it was also a period of great

political unrest with lots of strikes

and unions that led to the rise of

marget Hatcher and you have lived

through all of this so can you do me the

favor and take me back to your child

childhood and your teenage years what

was it like growing up in London in the

UK in the 50s and 60s and '70s let's get

inside a time capsule what are some

memories that stand out to you can you

paint the picture for me yeah so you've

done your homework I see um look it the

times were hard in some ways they were

great in others as you've pointed out

the times weren't terribly hard for me

um the times were hard for my

parents because um their generation had

lived through two world wars a

depression their life was much tougher

than mine has ever been okay um and my

father came back from the Army where he

fought in the second world war married

my mother um we lived in a workingclass

suburb of South London my father was a

manual laborer my mother was a home

maker um

but they did experience rationing it

didn't affect me because I was a kid

okay and so they had a hard

time uh my life was much easier than

theirs as I've explained and a feature

of the time is this the there was a

post-war labor government led by Clement

Atley and uh they were one of the most

radical governments that the UK ever had

so they produced the natural National

Health System they uh uh created a a

national power grid um they nationalized

the railways uh they made it possible

for workingclass kids like media

University they paid their fees their

college fees gave them assistance

allowance so uh a workingclass kid like

me could never have gone to University

20 years

before um but they made it possible the

the the changes that the the working

class that the labor government made

okay so uh it was also a time of

economic expansion because of the postwar

postwar

boom um and and that changed the climate

of the place I mean you know Britain and

Europe in the 40s and 30s have been kind

of had suffered from the depression and

the war and so on whereas this this was

now all behind us and um the the the

quality of living was Rising the the

opportunities of workingclass kids were

rising and as you pointed out this

changed an enormous change in the social

moras um good in many ways had some

downsides but it was very exciting to live

live through

through

so um although I was a working class kid

um there was an institution called the

grammar school yeah which kids set an

exam at their primary school at the age

of 11 11 plus 11 plus and the ones who

did well enough were taken to a grammar

school which gave them a relatively

academic education yep I was fortunate I

got creamed off um and I decided I want

to go to university uh so I applied to

University and um was fortunate to get

in to to Cambridge my mother was you

know over the moon uh my father was not

so pleased but that's another story um

and at school I fell in love with

mathematics so I went to study

mathematics at Cambridge and um over the

course of that I discovered that

actually I was more interested in

philosophy so I carried on with

mathematics my doctorate is actually in

mathematics as well although it's in

mathematical logic um but by the time I

finished I knew two things first

philosophy was a lot more fun than

mathematics and secondly I would only

ever be a very mediocre mathematician so

um I wanted a job in the philosophy

department and the first job I was ever

ever offered uh was a temporary job at

the University of sandre it was even

philosophy I don't know I have no idea

why they offered it to me with my

background but I'm delighted they did so

I I got a job in philosophy and that's

where I've been ever since when you

spoke about your childhood and teenage

years and the background do you think

that meu contributed towards your love

for philosophy I know you said that your

first love was mathematics but while you

were at University you started finding

philosophy a lot more stimulating

started leaning in that direction do you

think that contexts contributed to us a

natural inclination and I say this

because I sense this in the four years

that I lived in the UK and a lot of

people might call this crazy but I often

felt a sense of depth and Prof

profoundness to a lot of artifacts of

British culture whether it's the music

or the literature or the Arts or the

Poetry there was a weight to everything

there was I always got this feeling

there's more than what you see you can

just take some of the most popular songs

of the time take any song of The Beatles

or the Rolling Stones or Le Zeppelin

apart from what the song is actually

talking about always felt there's an

undercurrent of some philosophical

questions like existentialism or

nihilism questions about identity I also

always and this might be completely

crazy but a sense of melancholy that's

always attached with a lot of British

literature poetry even the happiest

songs and the happiest movies in

contrast to something like American pop

culture which is and this is a criminal

generalization but I just feel like it's

more of what you see is what you get not

as much depth as I saw in the British

cult does this make sense am I talking

crazy have you ever felt this depth to

British culture as well look there

there's a big difference between

American culture and British culture and

I haven't lived in Britain now for many

years so I'm not sort of up to date with

what's going on in the UK but uh of

course Britain has a history in a way

that United States does not now I know

the United States goes back to the 16th

century um so it has more history than

Australia which is the country I've

lived in most uh which has a history

that barely goes back 200 years um but

that does give it a kind of richness in

terms of its history its Traditions

which can be both interesting and sort

of also very constraining um its

architecture its musical history its

literature history and so on so that

that that's there now I must say that

virtually none of that had any effect on

me growing up in a workingclass culture

because um these things are just not

part of a workingclass culture right you

know um my both my parents were not well

educated although I love them dearly um

but they didn't play classical music

they didn't talk about they read cheap

newspapers um they didn't watch

intellectual television when we were

Rich enough to afford a television and

so so so the culture had no impact on me

then okay it changed when I went to

Cambridge and uh I was introduced

to culture High culture uh and I came to

understand something about the world of

politics and literature and restaurants

and um all the other things that you

allude to and pop culture was a part of

that I mean you talked about the Beatles

these guys changed pop music um until

then pop music was all about love

falling in love falling out of love and

they started writing about money death

um Insanity all within the space of a

few years they didn't last very long

they're only going for about six years

seven years well once they you know once

they became popular it was only about

six years a decade Max a decade Max um

but they they changed the topic of the

discussion fion and of course they were

fantastic musicians so if you look at

their early stuff compared with their

later stuff there's no comparison about

the musical sophistication now a lot of

that is due to George Martin okay that

sometimes called the fifth Beetle um but

they they did change

the focus both Musical and topical of

pop music and where they went everybody else

else

followed okay uh so do you think that

contributed towards that inclination

towards Phil phos opy because just the

music you're surrounded with just

everyday mainstream culture is dripping

with so many philosophical question do

you think that helped

no I'll tell you what did though I was

brought up as a Christian my mother was

a Christian she sent me to church every

week it was um a Protestant sort of

leftwing protestant congregationalist

which a group which doesn't exist anymore

anymore [Music]

[Music]

um and so I was a kind of devout

Christian I mean I I I I I became an

atheist when I was at University and I

still am but for those years I was a

kind of Fairly devout Christian um and

we had a fairly young

Minister who talked to the the kids of

the church about what I would Now call

philosophical issues about you know the

nature of God um about the meaning of

Love um and he' just come out of the

ological college so he was he wasn't old

school but uh that gave me an interest

in what I would Now call philosophical

topics so I started to read a bit and uh

I guess that was my first engagement

with philosophical issues although I

knew I couldn't even spell the word at

that time um so it was really the

philosophy of religion which first

engaged my philosophical interests um

and you know I still think about that

sometimes nowadays although my

philosophical interests have gone a long

way since then but uh in answer to your

question it was really the engagement

with theological issues which started to

motivate my interest in philosophical

questions very interesting right your

have philosophy of religion is probably

for a lot of kids as well the first

foray into like some deep philosophical

questions it can be it it can be you

spoke about moving from mathematics to

philosophy do you think coming into the

world of philosophy with no prior

background no expertise worked in your

favor coming in from a rigorous feeli

like mathematics or do you feel like it

worked against you while just trying to catch

catch

up well I I certainly had to play

catchup ball uh when I started the job

as a professional philosopher I didn't

know new so I've spent 50 years teaching

myself and I must just say it's been a

blast you know I've enjoyed every minute

of it um okay coming from the background

I did was it an advantage yes for two

reasons first of all I had the

techniques of mathematical logic under

my control which I could use to do

philosophy so often I do philosophy in a

fairly technical way not always but when

I find it helps um and a lot of

philosophers don't have these techniques

under their control and they they have

very good uses

sometimes but second and perhaps more

importantly uh the fact that I didn't

know any

philosophy was an advantage in this

sense that if you do a degree in

philosophy you know what philosophy is

about I mean you've been educated in a

certain way and you think wow that's

philosophy right and something that

falls outside the scope of that you

think well that's not really philosophy

many examples of this maybe we'll come

back and talk about Asian philosophy in

two course um I didn't have any

preconceptions so um with my background

I was interested in the bits of

philosophy that engage with mathematics

philosophy of mathematics mathematical

logic and so on that's where I started

but I soon discovered

that if you're interested in one bit of

philosophy it kind of stretches out it

has tentacles to all other bits yeah in

the end it all connects up so you you're

studying one thing you see oh well

that's related to this let me go and

explore that and which is what I did and

um so I've educated myself in so many

areas but I never had the thought oh

well that's not philosophy I'm not going

to go there so didn't matter whether

it's Asian tradition s or

uh uh physics

or uh politics it's all all fair game uh

and so I just followed my interests

wherever they went and that led me to

places where philosophers wouldn't have

gone at that time uh so I educated in

the UK um so-called analytic philosophy

that's sort let's call it english-

speaking philosophy was dominant um

there are other traditions of course um and

and

I assume that that's what philosophy was

about and a lot of people at that time

would not have given any Credence to uh

non-english speaking philosophy let

alone the Asian Traditions but for me if

it was interesting i' went there I

completely agree and there's this always

been this strong tussle between the art

and the Sciences but if I can bring an

analogy I feel

like coming in with no preconceived

notions allowed you to have that artist

level of lose flexibility and creativity

where you could just full things that

you feel are relevant and try and

connect the dots and this is why in a

lot of your work you have gone you have

transcended a lot of convention and gone

to places that conventional philosophers

have not found um well appeasing to them

I guess but it's actually been some

really powerful work so I completely

agree I think this worked for everyone's

benefit I'm glad you did it oh well

thank you let's start exploring some of

your work let's dive deep into it let's

start with logic in your classic

textbook logic a short introduction you

introduce a subject with this snippet

from LS carols through the Looking Glass

where Alice meets this logic chopping

pair of Tweedle Dum and Tweedle D who

say to her I know what you're thinking

about said Tweedle dumb but it isn't so

know how contrary wise continue Tweedle

D if it was so it might be and if it was

so it would be but as it isn't it ain't

that's logic MH unfortunately I'm still

confused so let's start at Rock Bottom

let's start with the silliest question

possible what is logic can you define it

for me okay well look Louis Carol is a

kind of interesting character um uh he

was a mathematician but obvious

philosophical interests and the Alice

books are just full of philosophical

jokes you don't realize it if you're not

a philosopher but they they play on word

puns and bending philosophical ideas [Music]

[Music]

um so

uh he's a really interesting writer the

kids the books are kids books the Alice

books but they're not just kids books

for sure okay so in the passage you

allude to it's a parody okay uh Tweed

Dum or Tweed whoever it is is sort of

sort of reasoning but because it's a

Travy it's just you know it's not real

reasoning but it's a he's obviously

going through a sequence of inferences

as logicians say you know he's saying so

and so therefore such and such but it's

not the case therefore it so and so no

these kind this is kind of a train of

reasoning and

um the word logic means many things and

if you look at the history of philosophy

East and West you'll see it gets

many not always related

uses but at least as modern logicians

understand the [Music]

[Music]

term logic is really about what follows

from what and why so if you take a

serious piece of reasoning I mean we're

not talking about Tweedle Tweedle D but

we're talking

about um you know Arguments for the

existence of God for example of which

there are many in Western and Eastern

philosophy um it falls to a logician to

try and figure out how good that reasoning

reasoning

is um now you have to hear that in a

very specific sense because L reasoning

has got to start from somewhere logician

call these premises it's the things you

start from right and then you draw

conclusions from those and logicians

reckon the premises are someone else's

business logicians are only concerned

with what follows from what okay I mean

the premises are often the Philosopher's

business okay um and logicians are

concerned with how good the reasoning is

that follows the premises whether it

really does get you to the conclusion or

youve you've made a silly error in some

sense so that that is a a major concern

of logic

nowadays but there was

um a revolution in logic at the

beginning of the 20th century logic's

been studied East and West for two and a

half thousand years at

least but it was only at the beginning

of the 20th century that mathematicians

really got their hands on it liit had a

go but the mathematics for his day

wasn't really sufficiently well

articulated to do the job but by the end

of the 19th century it was

and so you get the great mathematical

logical revolutionaries of the late 19th

century people like the German

philosopher got mathematician got L

frager the philosopher logician Bertram

Russell uh in the UK uh and these guys

and others I mean there's there's a lot

of people working but they were two of

the major players started to apply the

mathemat the mathematical techniques to

an analysis of logical reasoning um both

in the subject and in the form so they

were both concerned with how

mathematicians reason that was the

subject but the form was the kind of

arguments that get used and they and

they applied mathematical techniques to

an analysis of those and this was such a

powerful tool that it changed math it

changed logic by a Quantum and we've

never gone back and we've discovered

that the application of those tools have

all kinds of applications that these

guys could never have dreamed of so

logic has gone through the roof in the

last century and has continued to go

through the roof in its applications in

computer science in linguistics in philosophy

philosophy [Music]

[Music]

um so nowadays the study of logic is a

highly mathematic or can can be a highly

mathematical subject I mean it sinks

into philosophical Roots so you find

yourself in in philosophical debates as

well that's you know one of the reasons

I love it because it's mathematics and

to come back to your question what what

is logic nowadays well logic is a the

use of certain mathematical techniques to

discuss reasoning and all the things

that go with that and that's a lot logic

is what follows from what and why and

then you brought the topic of the

application so I want you this is going

to be a series of silly questions but I

do want to linger on this why do we

study logic what is the benefit of

studying this isn't this just to use a

common phrase in quotes this Common

Sense are perfectly logical yes

no um logic is not about how people

actually reason that's the domain of

psychology okay logic is about how you

ought to reason the Norms of correct

reasoning if you like now one thing

we've learned from studies in cognitive

psychology is that most people reason

quite badly in fact

um there are standard mistakes that

people make even it must be said when

they studied logic 100 it's it's it's

kind of curious phenomenon um so um if

you want to figure

out what follows from what and why you

don't look at how Ordinary People reason

of course you know you got to start from

somewhere so that's a sort of starting

place but um you look at places where

people reason very carefully um Ma ma

matics law medicine um these people have

to reason very carefully otherwise they

just get things wrong so um if you're

looking at good reasoning those are good

places to start that's not where you

stop but that's a better place to start

than how the person on the clap and Omni

bus as the English put it

reasons um and you scrutinize what go

what's going on whe what they're doing

whether that's reasonable given what we

understand about truth probability

meaning um so immediately you're off

into all these deep philosophical Dives

about truth probability meaning and so on

um let's dive into it I'm sold I think

it is important let's start diving

further into logic so you brought up the

quantum jump or the leap that philosophy

took in the 19th century but this does

go way back all the way back to when

Aristotle or

Plato I recently found out there are

categories to logic so sometime now if

someone says that's perfectly logical

I'm going to ask them which type of

logic do you mean can you help me Define

the two big pillars of logic classical

logic and non-classical logic and let's

start with classical logic first what is

classical logic or Aristotelian logic

okay so um people often tend to identify

classical logic with arist in logic and

what you said suggests that you're

making that

identification um this is wrong

okay let's wind the clock back a

little let let's let's talk about the

West we can talk about the East if you

want but uh the the revolution in logic

was in the

west so let's talk about the West um in

the west logic was invented by the

ancient Greeks Aristotle and

stoics um who produced certain theories

of what follows from what and why the

theory that arot produced was called

syllogistic for want of a better term

yeah okay um ancient Greece was the

first major flourishing development of

logic in the

west um the next flourishing period was

um the medieval period both in the

Arabic cultures and the Latin cultures

so they took their Heritage from Greece

and built on it big time okay so they

worked largely with syllogistic and uh

they developed it added whole raft of new

new

tools um and the Beast that comes out of

it is very different from syllogistic

it's it's much more sophisticated and

Powerful theory of logic um and then

logic goes into a decline because it's

connected with especially in the Latin

West it's connected with scholasticism

and scholasticism gets um B out of

fashion because of the

Renaissance um so

people actually forget many of the Great

gains of medieval logic in the west um

until roughly the second half of the

19th century when you get the

mathematicians applying the techniques

of mathematics for the first time and

this is when you get what's now called

classical logic invented okay by got

love frager bertron Russell and others

yeah okay now um classical logic is a

misnomer has nothing much to do with the

logic of ancient Greece or any other

great ancient culture in fact it's

incompatible with

it um there are certain things certain

inferences which syllogism says are

valid which um modern logicians will

tell you are not

valid um so you cannot identify

traditional logic which is probably a

better name for syllogistic nowadays um

and classical logic so there was this

big revolution in logic um and the logic

developed by frager and Russell was so

much more powerful because of its

techniques than what had come before was

that anything that come before was not

exactly obsolete but pay um so some

Modern logicians refuse to look at the

history of logic just because it seems

kind of very much outdated that is a

mistake because there are things you can

learn by looking at the ancient

traditions which um contained insights

which got sort of pushed out the way in

the modern development so I'm not saying

that you can't you shouldn't go back and

examine the ancient Traditions but as a

as a tool of analyzing what follows from

what and why classical logic was so much

more powerful than what have gone before

that the rest soon became history

okay classical logic is not has then

nothing to do with the Classical period

but it's classical in another sense

namely it's the first sort of logic

you'll learn if you study logic at a

university nowadays okay um and there

are reasons for that it's simple you

only need to be able to count up to two

to do it right um but it's always had

problems and logicians have always known

that so uh almost as soon as classical

logic was invented within the next 10

years mathematicians and logicians were

worrying about some of the problems of

the new logic and in due of course this

has led

to the Discovery invention I'm not quite

sure what the right word is of logical

systems which diverge from classical

logic and unsurprisingly these are

called non-classical logic and

especially in the second half of the 20th

20th

century we've seen the development of so

many non-classical Logics

Logics

um and a lot of this is driven by what

some logicians and philosophers pered to

be inadequacies of classical logic

whether they are those those things are

inadequacies is something that

philosophers debate about and and that's

still a very live

debate um okay so there are now many

well-known nonclassic Logics you

mentioned intuitionistic

logic that's actually a creature of the

1920s although the philosophical ideas

go back to 1910s the Dutch mathematician

um um J Brower um but the logic itself

was an invention of another Dutch

logician heting in the 1920s and that's

one of the earliest non-classical Logics

there are others being developed around

that time yeah so by the 1950s there

were several non-classical Logics known

but the the big boom was the second half

of the 20th century which have taken

those non-classical Logics articulated

them explored them they've the the 50

years emitted lots of other different

kinds of non-classical iics so

um that's really I think the most

productive area of logic nowadays when

we when we start to explore these

non-classical Logics it's not classical

logic G away but we know pretty much

everything about it except for very

esoteric things which Now find their

life own in mathematics journals the

philosophical issues are really all in

the domain of debates between classical

and non-classic logic debates between

various non-classical Logics disc of

their properties and their features um

discussion of their philosophical

motivations okay that's that's where

logic has now been for 50 years and it

continues to you know develop big time

with no sign of stopping it I do want to

draw the the distinct characteristics of

these branches so let let me give you a

premise let's say I'm saying this Lego

block is white in classical logic you

say you just have to count up to two

what are the two possible outcomes you

could have in this uh well the statement

you just made is true or false that's it

that's it that's it so In classical

logic this Lego block is white could

either be true or false that's it and

the opposite of not true is always going

to be false the opposite of not false

it's always going to be true in

classical logic correct okay let's bring

non-classical logic into the picture to

create that contrast so now if I'm

saying the same thing the Lego block is

white in non-classical logic could be

true false and there's a third value

well okay there are many non-classical

Logics and they work on very different

principles but um a a major kind of

non-classical logic of and there are

many Logics of this kind is called many

valued logic okay and in many Valu logic

you go beyond the the ability to count

up to two so it might be three

four sometimes more um possibly even

infinitely many okay and we come back to

that I guess um

so your question was what might there be

beyond the two so let me answer that

question um a very

standard four valued logic has four

values true and true

only false and False only both or

neither those are the four values and

you find that in ancient Buddhist and

Indian thought too but that's another

story we talk about that if you want

to so um

valued logic hasn't found a lot of favor

in the history of logic because it's

been heavily influenced by

two but ironically the first person to countenance

countenance

three true false and neither was Aristotle

Aristotle

himself who in a a rather notorious

chapter of one of his texts the

interpret ton chapter n said you know

what about some of these things about

the future that are not determined yet

so let me update this slightly will the

war in Ukraine been going on at the end of

2025 okay um some things about the end

of 2025 are pretty determinate we now

know that Sun is going to rise on the

1st of December but the war in Ukraine

well said Aristotle the statement the

war in Ukraine is going on at the end of

2025 is now neither true nor false of

course at the end of 2025 it will become

either true or false but um now it's

neither true or false so he plays with

this third

value and there were debates about that

in the Middle Ages but generally

speaking the techniques you need to

develop that came with a revolution in

logic at the de of the 20th

century so i s that's the answer to your

question how there could be more than

two so this is intuitionistic logic the

one which has true false and neither no

no uh intuitionist logic is not a

finitely many valued logic that's

something you can prove quite easily

okay so uh that

that intuitionists think that some mathematical

mathematical assertions

assertions [Music]

[Music]

um which cannot at the moment be proved

or refuted you can't prove either them

or the negation it will be wrong to to

say that one of those is that that they

tend to identify truth with provability

so if you can't prove uh aent a sentence

or it's negation they they think well

then then there's a pretty clear sense

in which neither of those is true so in

a sense you do get violations of the

principle of excluded middle which says

everything is either one or either true

or zero either one or zero either true or

false so

they they have a which Builds on that

Insight however intuitionist logic is

not a many not a finitely many valued

logic so this actually belongs to a

different class of logic and the

techniques you need to handle that tend

to be rather different um we can go to

those if you want but just take my word

for it I'll take your word for it but

okay so just L on the subset in this one

subset of I guess intuitionist logic

when I'm saying this Lego block is white

if I can't prove it's true or false then

the default setting it's neither right

so the proof plays a very important role

for for intuitionists for philosophical

reason they they identified essentially

truth with

proof and if something is neither

provable nor refutable otherwise you

can't prove its opposite its

negation then neither of those is true

at least while we have no proof um but

if you think if you're if if you don't

identify truth with proof you can think

well one of these can be true we just

don't know which yet we haven't found it

and so a big debate between

intuitionists and sort of classical

logicians was precisely whether you

should identify truth with provability

and a number of

philosophers in the 20th century thought

it we should identify truth with

proability not just intuitionists

intuitionists

um so there's a skull of philosophers

called The Logical

positivists in

Austria and then later in the

anglosphere uh who who tended to

identify truth with verification which

is in mathematics provability

um so

uh some philosophers have identified

truth with provability it's it's a

thesis about truth the nature of Truth

and therefore contentious um and a lot

of philosophers will reject that identification

identification

so this is one of the things which Drive debates

debates

between intuitionist logicians and

classical logicians and others well

logical positive

is I guess the jury is still out on them

but at least in the foundations of

physics did cause a lot of damage with

this emphasis on proofs and then with

the Copenhagen

interpretation completely ruled out

quite a few interpretations of quantum

theory yeah so I mean there's a um

a sort of Spate of verificationism that

ran through Western thought end of the

19th and start of the 20th century it

derives from positivism not logical

positivism positiv people like M um and

it found various applications um often

the writings of the early writings of

Einstein on special relativity appear to

be driven by verificationist assumptions

yeah certainly um some aspects of the

early quantum theory were um the and S

of The Logical positivist philosophers

the ones people working in Vienna in the

1920 were mathematicians and and

physicists as well so the the

philosophical stuff and the scientific

stuff get sort of entangled in their

thought now logical positivism has

largely gone out of fashion it didn't

really it sort of a lot of the the

austrialian philosophers were either

Jewish or

leftwing and they didn't go down well

when the Third Reich took over Austria

so someone them were killed and some of

the left the ones who left tended to go

to mainly to America but also the UK and

so logical positivism morphed into a

slightly different view which is

sometimes called logical empiricism and

it tended it started to lose it its

identification of Truth with provability

so it got kind of deconstructed though I

hate that word by British english- Speaking

Speaking

philosophers in the 1950s and it has had

a sort of come back in in Oxford in the

1970s and 80s we can go into that if you

want but

largely that is now defunct how

important do you think are proofs and

what weight would you assign to them in

logic and Beyond because you see that in

math I think Greek mathematics was

driven by proofs and like lot of the

Eastern forms of mathematic probably did

not rely as much on proofs what is the

weight that you would Place personally

okay look uh proof has been Central to

mathem itics East and West it's also

been Central to philosophy East and West

M because no one says oh I no no good

philosopher says okay there's a God or

there's an external world or I'm a human

or there are no trees out there because

you know why would you be interested in

such a bold statement yeah they've got

to give you Arguments for this to make

them interesting okay and whe it's

mathematics philosophy or whatever so

all students are all all everybody

argues uh so that's the domain of logic now

now [Music]

um arguments have to start from

somewhere assumptions whatever um and as

I said before that tends to be someone

else's business not the logicians but uh

proof is what you need to analyze the

arguments that are given to you by

mathematicians or physicists or

philosophers or

whatever um so proof has always been

Central to these disciplines now

something that we've seen in the last

100 years mainly is axiomatics so this

is a very different kind of proof this

is where you make your assumptions

absolutely explicit they call axioms and

then if you're doing it really

rigorously you make your Cannons of

inference absolutely explicit too and

then you look at the proofs that can be

given in those axiim systems

now axum acatic proofs were invented in

ancient Greece I mean ukian geometry is

acatic but uh really mathematics with

the exception of uid uh was not acatic until

until

really the 18th 19th

century the proofs weren't aaic proofs

people that took their starting points

as things that were obvious and then

reason from

those um but nowadays in mathematics

nearly all reasoning is axiomatic if you

ask a modern mathematician for a proof

of something they'll say well what what

system am I reasoning in and they'll say

well it's either this Theory or that

theory here are the aims here are the

logical principles that govern now here

am I proce and so that has changed the

way that arguments are conducted in

mathematics uh in the 20th

century physics is

still there are axium systems um people

will put down physical axioms so axioms

of quantum theory but it's still a

relatively informal kind of reasoning

compared with what you find in pure mathematics

mathematics

nowadays I think very interesting the

weight of proofs and how that can drive

the system let's talk about the

other finite value system you brought up

which was and I'm going to bring it back

to the Lego so if this Lego block is

white you mentioned there's a case where

it could be true false or both which is

where I think things are starting to get

interesting so let's introduce

paraconsistent logic what is

ditheism well um you've got to

distinguish between par consistent logic

and ditheism they related and I'll

explain how but they're quite different

things okay so let's start with paraconsistency

come back to classical

logic there's a principle of [Music]

[Music]

inference nowadays it's usually called

explosion though it has various medieval

names which sound much more esoteric

like ex F SEO okay but what it says is

if your premises are

contradictory then everything follows so

if I reason from contradictory

premises any conclusion I draw is

good so here is a an instance uh let's

suppose that Trump is corrupt and Trump

is not corrupt then it follows that

um our sun has only three planets or

that the moon is made of je green cheese

or that um God created the world 3

seconds ago or anything

anything

um now if you tell people who've never

studied logic that that's a good

inference they'll go what it's highly

counterintuitive yeah okay but it's

valid in classical logic and there are

good reasons for this it's not as stupid

as it

sounds um but it is highly counterintuitive

[Music]

uh and that has led some logicians to

say well it shouldn't really be counted

as a valid inference in um a good logical

logical

Theory so especially since the N back

the 1950s we've seen the development of

Logics in which that inference is not a

valid inference and those are called par consistent

consistent

Logics now

um I warned you that classical logic is

not the same as

syllogistic um syllogistic is actually a

paraconsistent logic and Aristotle

himself points this out in the

analytics so in one sense paraconsistent

logic is not

new but the use of um mathematical

techniques has has changed the game as I

explained and classical logic it this

principle of inference is certainly valid

valid

um so modern mathematical paraconsistent

Logics uh are very different from

syllogistic just because of the the

nature of the subjects has changed so

much but that's paraconsistency par

consistency is the stud of Logics where

contradictions do not entail

everything okay okay so paraconsistency

is something to do with logic about what

dthis is the view that some

contradictions are

true so it's not a view about logic it's

a view about truth and what makes things

true and what kinds of things are

true okay

um and dthis has been uh highly

unorthodox since Aristotle so

Aristotle's logic is paraconsistent but

he certainly wouldn't have had a bar of

this thought that some contradictions

are true it's called that's called The

Law of noncontradiction and it's been

high Orthodoxy in Western philosophy

there are a few arguably exceptions but

most western philosophers have accepted

it the story in the East is a bit

different but again let's stick to the

West for the moment

um now what's the connection between

paraconsistency and dthis well if you

think that some contradictions are true

and if you think that everything follows

from the contradiction you've got to

infer that everything is true because

everything follows from the contradiction

contradiction

and okay that really is wacky

okay so if you're a dialist then unless

you're a wacky dialist and there may be

some um you've got to use a paraconsistent

paraconsistent

logic so that's a connection in one way

dotism really requires use to a

paraconsistent logic but most

paraconsistent logicians are not

dths um they think they're something

wrong with the inference of explosion

maybe on grounds of relevance there's

got no connection between the premises

and the conclusion right there's no

connection between the premise that

Trump is corrupt and not corrupt and the

conclusion that the Earth has or the sun

has three planets there's just no

connection yeah and traditional wisdom

in logic has always been there's got to

be some kind of connection between the

premises and the conclusion um so you

can be driven

to endorse a paraconsistent logic for

many reasons and one of those is the

fact that there is no relevance between

the pr conclusion so as I said many

paraconsistent auditions are not dsts

so dthis requires par consistency but it

does not go the other way okay so um

that's the sort of basic basics of an

answer to your question I think this is

a good point to introduce as an example

the Liar's Paradox what is the liar

Paradox why is it a good example of par

consistent logic well it's an it's an

example of ditheism and as we've said if

you're reasoning D about dithia a dithia

is a neologism it just means a true

contradiction and ditheism is the view

that some there are some Dias

right um and if you tell a philosopher

some contradictions are

true the next question the next

statement is likely to be you're crazy

but the next question is is like to be

what give me some examples yeah um and

um there are several putative examples

but the ones that have got the most

airtime in the philosophical liter in

the last 50 years have been the Paradox

of self- reference and now the liar

Paradox is a paradigm example of Paradox

of self- reference but there are many

more and perhaps we'll come back to that

later but let's stick with the LI

Paradox for a

moment so the LI Paradox we believe was

invented by an ancient Greek philosopher

called ules about the fifth century

BC um and uh it goes like this

so okay

we're in New York is that true yes MH

okay um the solar system has only three

planets is that true no that's false

okay now I'm going to ask you the the

same question about what I'm going to

say next so listen

carefully um this sentence is not

true is that

true there's a contradiction there yeah

okay so you know what's coming okay so

the sentence is this sentence is not

true well if it's true well it says it's

not true so if it's true it's not true

yeah okay so okay well then I guess it

must be not true hey but it says it's

not true so it's true so if it's true

it's not true if it's not true it's true

and um so it looks as though I mean if

it's either true or not true it's both

true or not true there's your dithia

yeah okay um

so that's the LIE Paradox that's why

dialist like

it it sounds like a logicians party game

you know something you can amuse your

friends with while the canop come out

okay uh and if you left the story like that

that

uh you would you could be forgiven for

thinking so but in fact um we know that

uh it's one of a large number of

paradoxes in that family which

appeared in the development of modern

logic around the turn of the 20th century

century

um and so this is not a logicist party

game really reasoning of this kind is

embedded in mathematical reasoning or at

least what people thought was mathematical

mathematical reasoning

reasoning

until a paradox of this kind was

discovered or invented by bertron

Russell um who was one of the events of

classical logic um it's now called

Russell's Paradox we can talk about that

if you want but for present purposes

just take my word that it's in the same

family as the liar

yep so um how you handle Paradox of this

kind has to be fair driven so much of

the development in logic in the last 100

years in fact I mean

the the liar Paradox has been discussed

in all the great periods of logic

ancient great logic Arabic and Latin

logic um and modern logic contemporary

Logic the last 100 years um because it it

threatens our very views about what

truth is because if you

suppose that things no contradictions

can be true you've got one that appears

to be true staring in the face what do

you say about it this see tends to

challenge our views about the nature of

Truth so you can understand why

philosophers got really worried about

this and it must be said that because

people tended to endorse the law of

non-contradiction they thought there

must be something wrong with the

argument you know something's got to go

wrong somewhere and the suggestions that

effect have been very very sophisticated

both in the medieval period And in the

modern period but even two and a half

thousand years after the Paradox was

invented discovered um

we don't know the solution at least if

consensus is required for knowledge

because there's still no agreement about

how the best way to solve the Paradox is

but dsts have come along and said look

you've been barking up the wrong tree as

the English say um you know you've been

trying to explain what's wrong with the

argument there's nothing wrong with the

argument um it's what it is what it

appears to be a veridical argument it

establishes the contradiction end of

story well it's not the end of the story

because then you say well okay but then

oh well if that's right you can't use

classical logic so what do we do okay so

that's you know where the story goes

next but your question was what might be

an example of a dithia that one and it's

kind of deeply entrenched in the history

philosophy so D to say it is what it is

and I think that can get quite make

people quite uncom able because we've

grown up with the idea that

contradictions are not stable it's

something to avoid I was surprised to

hear that Aristotle had already

referenced paraconsistent logic because

I was under the impression he would have

hated the idea of dilus because oh he

hates theism right he doesn't hate

paraconsistent logic syllogistic is par

consistent got it because in his book

metaphysics he argued he endorsed the

law of non-contradiction the principle

of the excluded Mill and he went on to

say it's not just a rule of thought but

a principle of being itself

yes we spoke about the liar Paradox you

reference Russell's Paradox there

similar contradictions of self-

reference and set theory is this similar

to Quantum Theory I'm going to dive into

physics a bit where there's a similar

contradiction that exists that unless

you measure a particle it is supposed to

be in the superp position of multiple

States the cat is both dead and alive

until you measure it this statement is

both true and false if it is similar

then will you go as as far as saying

that this contradiction is just a

reflection of the fact that our theory

is incomplete like quantum theory is

incomplete it's an error in the system

there's some hidden variables out there

there's work still to be done or would

you make the case that the

contradictions are embedded in the

system they're a feature of the system

they're not a bug

yeah okay um let let's return to quantum

mechanics in a second okay but uh let's

pick up where you started that people

assume that contradictions can't be true

because um there's this subject nowadays called

called

xfire nothing to do with

the uh the website called X um it's it's

short for experimental philosophy and in

in experimental philosophy people go

around and ask ordinary people what they

think about things of course it doesn't

show that what people think is true but

um people have done XR experiments

on um some questions where people are

quite happy to say that it isn't it

isn't so so an example is the sori

Paradox maybe we'll come back to that in

due course but it's sort of where you

get something that's sort

of vague or indeterminate yeah so it's

pouring down with

rain it's slowly stops until it isn't

raining anymore there's a kind of mid

position where it's sort of raining sort

of not raining it's sort drizzle you

know um and

X5 investigations ask people well can

you say it's rainy and it's not raining

they say yeah can you say it's neither

raining or not raining they yeah okay so

people are prepar the you know ordinary

person is prepared to uh endorse

contradictions so one thing xfire is

good at telling you is you know the

classical logician comes along and says

well no one endorses contradiction

because that's crazy and xfire shown

that's just wrong now it may well be the

case that if you studied Aristotle or

logic 100 or whatever you and your mates

are all going to say well these

contradictions can't really be true can

they but that's sort of preaching to the

choir in the

sense okay so um and of course once we

turn to Asian philosophy there's a whole

new ball game it keeps coming up maybe

we should talk about that in course um

all right um

but certainly most philosophers with

some notable exceptions including I

think Hegel have held

contradictions to be just rationally untenable

untenable

um Aristotle's arguments which establish

the principle of non-contradiction in

the history of Western philosophy um are

terrible and that's not just my view

that's what modern Scholars think about

it okay we can talk about that if you

like um nonetheless they were amazingly successful

successful

and what that says about sort of rationality

rationality

and assuming things on the basis of

argument that's another story but let's

leave that for the moment okay so you're right

um uh most philosophers have held most

western philosophers have held that

contradictions can't possibly be true so

dialetheism has got a lot of flak

because it was highly unorthodox and um

you know I've been sort of running with

it now for 40 years or more and the

first reaction you get from people who

haven't run across it before is that's

crazy okay so all that's true now okay

that's a rather long preamble to come

back to Quantum Mechanics yeah okay so

your question was about Shing as cat now

I'm not a Quantum mechanic I'm not a

physicist um

but sometimes the suggestion you make is

is made by people namely you've got this

cat in this kind of strange state

where maybe this cyanide capsule has

been released because of the decay of a

radioactive particle maybe not we just

don't know yeah uh if it has been

released if the C has been released then

the cat's dead if not not so um the cat

is in this kind of state which is

sometimes called a

superposition so some people have

suggested that this is a contradictory

State namely the cat is both alive and dead now as I say I'm not a Quantum

dead now as I say I'm not a Quantum mechanist

mechanist mechanic Quantum physicist Quantum

mechanic Quantum physicist Quantum physicist okay um but in my

physicist okay um but in my understanding is that is not a good

understanding is that is not a good description of the situation okay the

description of the situation okay the cat is in a superposed state um this is

cat is in a superposed state um this is described by something called a state

described by something called a state function and a state function is a very

function and a state function is a very strange entity

strange entity it's a map from states of Affairs to

it's a map from states of Affairs to well actually complex numbers so these

well actually complex numbers so these are mathematical enties but leave the

are mathematical enties but leave the precise nature aside what what it is is

precise nature aside what what it is is something which gives you probabilities

something which gives you probabilities yeah and what it gives you if you

yeah and what it gives you if you manipulate these State functions in a

manipulate these State functions in a certain way is the probability that when

certain way is the probability that when you open the box the cat will be alive

you open the box the cat will be alive and the cat will be dead but what the

and the cat will be dead but what the state of the system is before that is

state of the system is before that is this is described by the state function

this is described by the state function and the state function just

and the state function just is a map from states of Affairs to

is a map from states of Affairs to complex numbers or probabilities if you

complex numbers or probabilities if you like this domain of all

like this domain of all possibilities yes um each with a

possibilities yes um each with a probability attached to it so to say

probability attached to it so to say that the cat is both alive and dead is

that the cat is both alive and dead is just wrong it's to say that the system

just wrong it's to say that the system inside the box or the cat if you like is

inside the box or the cat if you like is in a very strange state which is only

in a very strange state which is only described by the quantum State the state

described by the quantum State the state function of it which is a very strange

function of it which is a very strange thing but it's perfectly

thing but it's perfectly [Music]

[Music] consistent but then going back

consistent but then going back to the question

about how intrinsic the contradiction is and whether you

and whether you believe just so quantum theory and Shing

believe just so quantum theory and Shing this cat many people have argued is a

this cat many people have argued is a reflection of how ridiculous quantum

reflection of how ridiculous quantum theories at the moment and it's a

theories at the moment and it's a reflection of how incomplete it is and

reflection of how incomplete it is and that there are some hidden variables out

that there are some hidden variables out there that we don't know which is why we

there that we don't know which is why we assume the super position and that's an

assume the super position and that's an absurd outcome do you think this

absurd outcome do you think this contradiction that we see in par

contradiction that we see in par consistent logic is it I take your point

consistent logic is it I take your point about it's not the same but do you think

about it's not the same but do you think this this perspective of this thought

this this perspective of this thought about we still incomplete that there's

about we still incomplete that there's still work to be done and that's why

still work to be done and that's why this contradiction exists or do you

this contradiction exists or do you think this contradiction is fundamental

think this contradiction is fundamental to the system it's embedded it's a

to the system it's embedded it's a feature of the

feature of the system no um look I I'm not a Quantum

system no um look I I'm not a Quantum physicist most of the qu physicists I

physicist most of the qu physicists I know uh uh just think this is silly yeah

know uh uh just think this is silly yeah okay to suppose that the um cat is both

okay to suppose that the um cat is both alive and dead is just to misunderstand

alive and dead is just to misunderstand the mathematics yeah there's more work

the mathematics yeah there's more work to be done it's incomplete yeah now

to be done it's incomplete yeah now [Music]

[Music] um that raises the question of how you

um that raises the question of how you interpret the mathematics

interpret the mathematics and that really is the big philosophical

and that really is the big philosophical problem of quantum

problem of quantum mechanics and um there are many many

mechanics and um there are many many interpretations uh the Orthodox one was

interpretations uh the Orthodox one was the Copenhagen interpretation from that

the Copenhagen interpretation from that 192s 1930s yeah

192s 1930s yeah um

um which

um was certainly influenced by positivism as you talked about

positivism as you talked about mhm

um but some philosophers weren't satisfied with this for example Einstein

satisfied with this for example Einstein was never satisfied with this um so he

was never satisfied with this um so he thought that the Copenhagen

thought that the Copenhagen interpretation must be

interpretation must be wrong and the question is is

how um and so you get these hidden variable

um and so you get these hidden variable theories pushed by people like

theories pushed by people like boom uh which says look there's got to

boom uh which says look there's got to be more to the story there's something

be more to the story there's something that the mathematics is not telling you

that the mathematics is not telling you let me suggest what it is and go on okay

let me suggest what it is and go on okay so um is that the case of par consistent

so um is that the case of par consistent Logic No no no uh no Quantum physicist I

Logic No no no uh no Quantum physicist I know endorses paraconsistent logic

know endorses paraconsistent logic oralism um there is a real question

oralism um there is a real question about how you understand the mathematics

about how you understand the mathematics of quantum mechanics um and I think

of quantum mechanics um and I think both the Boman Theory and the Copenhagen

both the Boman Theory and the Copenhagen Theory are now sort of sort of ceasing

Theory are now sort of sort of ceasing to find favor that and that's connected

to find favor that and that's connected with various empirical results um uh

with various empirical results um uh involving entanglement um but that's

involving entanglement um but that's another story um and so we've seen the

another story um and so we've seen the development of new interpretations such

development of new interpretations such as the many world theory yeah ever and

as the many world theory yeah ever and Weaver

Weaver um uh but to the extent that I

um uh but to the extent that I understand the state of play there's no

understand the state of play there's no consensus about how you interpret the

consensus about how you interpret the mathematics of quantum theory nowadays

mathematics of quantum theory nowadays but no Quantum theorist I've spoken to

but no Quantum theorist I've spoken to has ever suggested

has ever suggested dotism keep the physics aside I just

dotism keep the physics aside I just what the only analogy I want to drive

what the only analogy I want to drive here is like they feel the theory is

here is like they feel the theory is incomplete and that there are hidden

incomplete and that there are hidden variables do you get the feeling that in

variables do you get the feeling that in the world of philosophy the approach to

the world of philosophy the approach to these contradictions is also that it's

these contradictions is also that it's incomplete and there's work to be

incomplete and there's work to be done well yeah but that's a kind of

done well yeah but that's a kind of trism because philosophy has never

trism because philosophy has never finished look we've been creating we

finished look we've been creating we philosophers have been creating

philosophers have been creating philosophical theories East and West

philosophical theories East and West for at least 3,000 years probably

for at least 3,000 years probably longer uh and we know that the

longer uh and we know that the philosophical theories that are

philosophical theories that are produced uh have strengths and

produced uh have strengths and weaknesses um it's the weaknesses which

weaknesses um it's the weaknesses which drive us to create new theories is

drive us to create new theories is trying to preserve the strength the good

trying to preserve the strength the good things they do get rid of the weaknesses

things they do get rid of the weaknesses um and this has produced the Dynamics of

um and this has produced the Dynamics of the production of philosophical theorist

the production of philosophical theorist for 3,000 years and we ain't at the end

for 3,000 years and we ain't at the end yet so philosophy is an iate always will

yet so philosophy is an iate always will be a work in progress yeah I guess the

be a work in progress yeah I guess the big question I'm driving towards is the

big question I'm driving towards is the contradiction that you see in physics

contradiction that you see in physics has largely been viewed as incomplete

has largely been viewed as incomplete work to be done absurd to a certain

work to be done absurd to a certain extent whereas let's say a contradiction

extent whereas let's say a contradiction that you've seen or what girdle has

that you've seen or what girdle has pointed out with this incompleteness

pointed out with this incompleteness theorems about you can have statements

theorems about you can have statements that are true and not provable a system

that are true and not provable a system can never be complete and consistent at

can never be complete and consistent at the same time that implies that this

the same time that implies that this contradiction is not incomplete or it's

contradiction is not incomplete or it's not that work needs to be done it's just

not that work needs to be done it's just an inevitable fundamental feature of the

an inevitable fundamental feature of the system itself so and I guess the

system itself so and I guess the question do you view par consistent

question do you view par consistent logic in the same lens that these

logic in the same lens that these contradictions are just embedded they're

contradictions are just embedded they're intrinsic to the system that you're

intrinsic to the system that you're working

working [Music]

[Music] in okay you've raised girdle theum uh

in okay you've raised girdle theum uh that I wouldn't really agree with

that I wouldn't really agree with exactly how you described it but let's

exactly how you described it but let's let's finesse that for a moment uh we

let's finesse that for a moment uh we come back to GLE serum if you want

come back to GLE serum if you want um what I just said was that any

um what I just said was that any philosophical Theory and for that matter

philosophical Theory and for that matter any logical theory is always going to be

any logical theory is always going to be fallible we know they have strengths and

fallible we know they have strengths and weaknesses and we try to find better

weaknesses and we try to find better ones so anything Theory you have could

ones so anything Theory you have could be overthrown in the future probably

be overthrown in the future probably will be in

will be in fact uh one hopes that the new theories

fact uh one hopes that the new theories preserves the strength so it can do the

preserves the strength so it can do the things that the old theories did but um

things that the old theories did but um nothing sort of hangs around

nothing sort of hangs around forever now uh that's true of

forever now uh that's true of paraconsistency ditheism for sure um is

paraconsistency ditheism for sure um is there

there something inherent par consistency in

something inherent par consistency in ditheism which makes it inevitable that

ditheism which makes it inevitable that we'll be overthrown no no more than any

we'll be overthrown no no more than any other Theory I think so there's a

other Theory I think so there's a general point that it'll probably go but

general point that it'll probably go but I I don't I think it' be wrong to

I I don't I think it' be wrong to interpret the fact that dum is

interpret the fact that dum is inconsistent as a Mark that there must

inconsistent as a Mark that there must be a problem somewhere and we better

be a problem somewhere and we better find it I mean that's the kind of

find it I mean that's the kind of mistake well I think it's a mistake it's

mistake well I think it's a mistake it's contentious that people have been making

contentious that people have been making with a live Paradox for two and a half

with a live Paradox for two and a half thousand years yeah there must be

thousand years yeah there must be mistake we got to find it um and that's

mistake we got to find it um and that's exactly what Dil ISM um challenges

exactly what Dil ISM um challenges problematizes so I don't think the fact

problematizes so I don't think the fact that a viewer is inconsistent tells you

that a viewer is inconsistent tells you that

that that that's a Mark that it must be wrong

that that's a Mark that it must be wrong it may be wrong like all theories but I

it may be wrong like all theories but I don't think it's contradict nature tells

don't think it's contradict nature tells you there's something that is which must

you there's something that is which must push you towards getting rid of it that

push you towards getting rid of it that makes sense yeah that was the big

makes sense yeah that was the big question that was driving driving

question that was driving driving towards you brought up the sorites

towards you brought up the sorites Paradox let's talk about that as well

Paradox let's talk about that as well in elements of philosophy Thomas Hobbs

in elements of philosophy Thomas Hobbs had proposed the ship of thesis thought

had proposed the ship of thesis thought expiran if there's a really old ship you

expiran if there's a really old ship you rebuild it plank by plank at what point

rebuild it plank by plank at what point does it become a new ship which is I

does it become a new ship which is I guess also a subset of the sorites

guess also a subset of the sorites Paradox it's one of the sortis paradoxes

Paradox it's one of the sortis paradoxes one of them so I've thrown on the all of

one of them so I've thrown on the all of this jargon let's formally Define it

this jargon let's formally Define it what is fuzzy logic what is the SES

what is fuzzy logic what is the SES Paradox all

right so sori's paradoxes

paradoxes um were invented discovered in ancient

um were invented discovered in ancient Greece probably about the same time as

Greece probably about the same time as the liar

the liar Paradox and

Paradox and um they involve Concepts which appear to

um they involve Concepts which appear to be

be imprecise so let's leave the ship of

imprecise so let's leave the ship of thesis aside for the moment let's come

thesis aside for the moment let's come back to the Rain

back to the Rain example is it raining well sometimes the

example is it raining well sometimes the answer is yeah obviously sometimes the

answer is yeah obviously sometimes the answer is no obviously but then

answer is no obviously but then um it's not there's to say it's raining

um it's not there's to say it's raining is a bit vague it kind of it sort

is a bit vague it kind of it sort of the rain sort of Fades out and so

of the rain sort of Fades out and so does your temptation to say that it's

does your temptation to say that it's raining with

raining with it um

so [Music]

[Music] um what seems pretty

um what seems pretty clear is that sort of very very small

clear is that sort of very very small change is don't change the

change is don't change the state so suppose it's ABS pissing down

state so suppose it's ABS pissing down okay um if you change if you stop one

okay um if you change if you stop one drop of rain it's still pissing down

drop of rain it's still pissing down right generally speaking you know if

right generally speaking you know if there are a million raindrops falling in

there are a million raindrops falling in a second and you change that to

a second and you change that to 9,99 9,900 well one less one less one

9,99 9,900 well one less one less one less yeah uh it's it's still raining

less yeah uh it's it's still raining Okay so if if a state holds and you

Okay so if if a state holds and you change a very very small

change a very very small amount then it's still raining

amount then it's still raining okay same with any of these sorries like

okay same with any of these sorries like predicates like color for example supp I

predicates like color for example supp I got something that's red that's slowly

got something that's red that's slowly changing to Blue okay um if something is

changing to Blue okay um if something is red and I change the wavelength by one

red and I change the wavelength by one angstrom um it's still red okay so this

angstrom um it's still red okay so this is sometimes called a principle of

is sometimes called a principle of Tolerance and it generates this s's

Tolerance and it generates this s's Paradox

Paradox so start with something like it's

so start with something like it's raining or it's red or whatever and you

raining or it's red or whatever and you change it a very very small amount it's

change it a very very small amount it's still raining or red so it's raining or

still raining or red so it's raining or it's red let's change it one very very

it's red let's change it one very very small amount it's still rainy or it's

small amount it's still rainy or it's red okay and you can keep going and

red okay and you can keep going and every time if you start with something

every time if you start with something that's red say and you change your very

that's red say and you change your very small amount it's still red but in due

small amount it's still red but in due course this is no longer the case face

course this is no longer the case face it's blue um but reasoning you can infer

it's blue um but reasoning you can infer that it's red because you can reason all

that it's red because you can reason all the way down the chain

the way down the chain yeah so that's the sores Paradox you

yeah so that's the sores Paradox you seem to be able to reason your way down

seem to be able to reason your way down the chain and um prove something that's

the chain and um prove something that's manifestly not the

manifestly not the case um okay oddly enough the sori's

case um okay oddly enough the sori's Paradox wasn't greatly discussed in the

Paradox wasn't greatly discussed in the medieval period why I've never been sure

medieval period why I've never been sure but it's been analyzed big time by

but it's been analyzed big time by logicians since at least the

logicians since at least the 1950s and as you might guess many people

1950s and as you might guess many people have suggested possible

have suggested possible solutions fuzzy logic is one of

solutions fuzzy logic is one of them uh actually there are many fuzzy

them uh actually there are many fuzzy Logics but what they have in common is

Logics but what they have in common is the thought that okay that fuzzy Logics

the thought that okay that fuzzy Logics are many value Logics let's come back to

are many value Logics let's come back to that where um you've got an infinite

that where um you've got an infinite number of truth values so typically a

number of truth values so typically a fuzzy logic has a truth value for every

fuzzy logic has a truth value for every real number between zero and one

real number between zero and one so take all the real numbers between

so take all the real numbers between zero so real numbers are things like you

zero so real numbers are things like you know

know um whole numbers

um whole numbers fractions decimal expansions some of

fractions decimal expansions some of which are not fractions like pi and

which are not fractions like pi and root2 and so on so all all those numbers

root2 and so on so all all those numbers between zero and one so the thought is

between zero and one so the thought is that

that the truth of the statement this is read

the truth of the statement this is read comes by degrees which is a very natural

comes by degrees which is a very natural thought it starts off really really true

thought it starts off really really true ends up really really false and then as

ends up really really false and then as you run down the sorries um it sort of

you run down the sorries um it sort of gets less and less

gets less and less true um so the thought is that truth

true um so the thought is that truth values

values themselves are measured by real numbers

themselves are measured by real numbers they start off with one which is really

they start off with one which is really really true uh end with zero which is

really true uh end with zero which is really really false and then as you go

really really false and then as you go down the sortis the truth value slides

down the sortis the truth value slides down from one to zero okay so that's

down from one to zero okay so that's how fuzzy logic is deployed in a attempt

how fuzzy logic is deployed in a attempt to solve the sori's

Paradox I guess I'm looking for one possible example of how it solves it so

possible example of how it solves it so we had the ship of thesis there are

we had the ship of thesis there are these old problems of xenos paradoxes

these old problems of xenos paradoxes Xeno zaro and then I guess Modern

Xeno zaro and then I guess Modern Problems you can you can apply this to

Problems you can you can apply this to anything aging at what point do I become

anything aging at what point do I become 31 from 30 when does Consciousness

31 from 30 when does Consciousness emerge in a kid what would be one

emerge in a kid what would be one possible solution to this well I mean

possible solution to this well I mean soos paradoxes are R different actually

soos paradoxes are R different actually let's let's bracket those for the moment

let's let's bracket those for the moment but

but the fuzzy solution to any of these

the fuzzy solution to any of these paradoxes and you're right they're

paradoxes and you're right they're they're ubiquitous because virtually all

they're ubiquitous because virtually all the categories all the predicates we use

the categories all the predicates we use outside mathematics and maybe physics

outside mathematics and maybe physics had this kind of

had this kind of vagueness and you know like being an

vagueness and you know like being an adult being drunk

adult being drunk um they're all vague so they all

um they're all vague so they all generate these sties now um the fuzzy

generate these sties now um the fuzzy solution is that um you if if you try to

solution is that um you if if you try to apply classical logic you're forgetting

apply classical logic you're forgetting the fact that the truth values aren't

the fact that the truth values aren't one or zero they can be intermediate

one or zero they can be intermediate between them and as you run down the

between them and as you run down the sori's progression that's essentially

sori's progression that's essentially what happens you start off with one then

what happens you start off with one then it becomes three quarters and then a

it becomes three quarters and then a half then a quarter then finally

half then a quarter then finally zero now um that's the basic idea that

zero now um that's the basic idea that actually does not tell you how to solve

actually does not tell you how to solve the sidus Paradox because that in itself

the sidus Paradox because that in itself does not tell you how to address the bit

does not tell you how to address the bit of reasoning I gave you this is red if

of reasoning I gave you this is red if this is red that is

this is red that is red if that is red this is red if that

red if that is red this is red if that is red this is red if that is red this

is red this is red if that is red this is

is so you're applying a chain of inferences

so you're applying a chain of inferences and each inference is kind of straight

and each inference is kind of straight is is what Mo logicians call modus

is is what Mo logicians call modus ponents this is the case and if this is

ponents this is the case and if this is the case that is the case so that is the

the case that is the case so that is the case logicians call that modus ponents

case logicians call that modus ponents and it's just a chain of modus ponent

and it's just a chain of modus ponent inferences and so saying that okay

inferences and so saying that okay you've you've ignored the fact that

you've you've ignored the fact that there are degrees of truth doesn't tell

there are degrees of truth doesn't tell you what to say about

you what to say about that but you can tell various stories

that but you can tell various stories using that thought to apply to this kind

using that thought to apply to this kind of reasoning there are more than one

of reasoning there are more than one there's more than one way of doing it

there's more than one way of doing it how you do it depends on other things

how you do it depends on other things that get involved in the formal

that get involved in the formal logic um we can go into those if you

logic um we can go into those if you want but probably it's best to avoid

want but probably it's best to avoid those technicalities at the moment but

those technicalities at the moment but the basic idea is that truth comes by

the basic idea is that truth comes by degrees and that if you apply that

degrees and that if you apply that thought in a certain way then you can

thought in a certain way then you can analyzing the theoretical reasoning and

analyzing the theoretical reasoning and show what's wrong with

show what's wrong with it I want to pull back and ask you some

it I want to pull back and ask you some big picture questions about philosophy

big picture questions about philosophy all of this has been extremely

all of this has been extremely interesting to

interesting to me but it's also made me

me but it's also made me think about you mentioned the word party

think about you mentioned the word party tricks like all of this just being word

tricks like all of this just being word play to a certain extent Ludwick

play to a certain extent Ludwick wienstein had once said that philosophy

wienstein had once said that philosophy is a battle against the bewitchment of

is a battle against the bewitchment of our intelligence by the means of

our intelligence by the means of language you have explored this in your

language you have explored this in your book beyond the limits of thought

book beyond the limits of thought calling it the limits of the expressible

calling it the limits of the expressible Emanuel Kant had wrestled with the idea

Emanuel Kant had wrestled with the idea of antinomies how strong is this

of antinomies how strong is this coupling between logic and language and

coupling between logic and language and then logic and

then logic and thought when you say when you talk about

thought when you say when you talk about these paradoxes when you talk about

these paradoxes when you talk about these thought experiments how much of

these thought experiments how much of this is just linguistic semantics party

this is just linguistic semantics party tricks like you mentioned this sentence

tricks like you mentioned this sentence is both true and false how much of that

is both true and false how much of that is just word play or do you think logic

is just word play or do you think logic is this real and objective entity out

is this real and objective entity out there language is just one way of

there language is just one way of tapping into whatever it is or do you

tapping into whatever it is or do you think it's a consequence of the language

think it's a consequence of the language we

use well you're right about Vicken Stein u i mean he changed his views about many

u i mean he changed his views about many things over the course of his life but

things over the course of his life but um The View that you quoted pretty much

um The View that you quoted pretty much stays with him most of the time that

stays with him most of the time that philosophical problems are caused by um

philosophical problems are caused by um an abuse of language and once you

an abuse of language and once you understand how language Works they

understand how language Works they disappear

disappear yeah

yeah [Music]

[Music] um I don't I certainly don't believe

um I don't I certainly don't believe that

that view uh and I don't think many

view uh and I don't think many contemporary philosophers believe that

contemporary philosophers believe that view which is not to say that some

view which is not to say that some philosophical problems are be caused by

philosophical problems are be caused by linguistic

linguistic confusion

confusion um so for example we might have a

um so for example we might have a philosophical problem which is caused by

philosophical problem which is caused by using a word which has two meanings and

using a word which has two meanings and getting them

getting them confused that often

confused that often [Music]

[Music] happens so once you're clear that there

happens so once you're clear that there are um there's a confusion about the use

are um there's a confusion about the use of language then that solves that

of language then that solves that problem you know maybe you've got a word

problem you know maybe you've got a word that is used in two premises

that is used in two premises let I mean this is a silly example but

let I mean this is a silly example but suppose it's the word

suppose it's the word Bank

Bank okay um now bank is ambiguous it can

okay um now bank is ambiguous it can mean where you get your money from or it

mean where you get your money from or it can mean what runs down by the side of

can mean what runs down by the side of the river yeah so if I got two premises

the river yeah so if I got two premises and one is only true because I'm using

and one is only true because I'm using the word this way and one's only true if

the word this way and one's only true if I'm using the word that way and then I

I'm using the word that way and then I put them together I'm I'm going to get

put them together I'm I'm going to get silly conclusions okay that I mean no

silly conclusions okay that I mean no one would be sort of confused by that

one would be sort of confused by that but philosophical problems I mean when a

but philosophical problems I mean when a word use has different meanings it's not

word use has different meanings it's not always as clear as that okay so some

always as clear as that okay so some philosophical problems probably can be

philosophical problems probably can be solved by getting clear about language

solved by getting clear about language but often the really hard philosophical

but often the really hard philosophical problems begin once you've clarified

problems begin once you've clarified what your language

what your language [Music]

[Music] means

so okay where do we start um look let's let's take an Ethics

look let's let's take an Ethics problem um

problem um which is kind of a Hot Topic at the

which is kind of a Hot Topic at the moment in this country okay um some

moment in this country okay um some people think it's immoral and they deed

people think it's immoral and they deed should be illegal to have an abortion

should be illegal to have an abortion some people think that they have a moral

some people think that they have a moral right to an abortion and that in fact

right to an abortion and that in fact laws that prevent abortion are

laws that prevent abortion are themselves in moral and maybe under

themselves in moral and maybe under certain

certain circumstances now

circumstances now um that is not a problem that goes away

um that is not a problem that goes away when you get language clear

I mean okay exactly how you defined abortion might be contentious but let

abortion might be contentious but let let's sort of agree on you know a

let's sort of agree on you know a reasonable definition of abortion

reasonable definition of abortion um well the word immoral can be kind of

um well the word immoral can be kind of be unclear sometimes illegal being so I

be unclear sometimes illegal being so I maybe these words need some Tiding up

maybe these words need some Tiding up and cleaning up but in the end even when

and cleaning up but in the end even when you've cleaned it up um the the

you've cleaned it up um the the disagreement remains um and that's that

disagreement remains um and that's that problem is not going to be solved by

problem is not going to be solved by simply paying attention to how you use

simply paying attention to how you use language it's there's something else

language it's there's something else going on

going on here okay that's problem of Ethics

here okay that's problem of Ethics um interestingly enough viin never

um interestingly enough viin never really applied his view to ethics um he

really applied his view to ethics um he was much more interested in

was much more interested in metaphysics epistemology you know what

metaphysics epistemology you know what some philosophers called theoretical

some philosophers called theoretical philosophy as opposed to practical

philosophy as opposed to practical philosophy um but even when it comes to

philosophy um but even when it comes to you know theoretical philosophy uh I

you know theoretical philosophy uh I think most philosophers now would hold

think most philosophers now would hold that you're you're not going to solve

that you're you're not going to solve substantial philosophical issues just by

substantial philosophical issues just by getting your word straight you get your

getting your word straight you get your word straight to avoid confusion and

word straight to avoid confusion and that's where the real real problem

starts so there is something objective real mind independent about logic that

real mind independent about logic that exists that transcends language and

exists that transcends language and thought let me let's run this thought

thought let me let's run this thought experiment let's say aliens land on

experiment let's say aliens land on Earth tomorrow we don't speak the same

Earth tomorrow we don't speak the same language have varying degrees of

language have varying degrees of intelligence but do you think there will

intelligence but do you think there will be mutual agreement on the fact that

be mutual agreement on the fact that there is this objective entity out there

there is this objective entity out there called logic that we can all ascribe to

called logic that we can all ascribe to and maybe their language ascribes to a

and maybe their language ascribes to a much higher level to

it well first of all don't identify philosophy with logic I mean um are

philosophy with logic I mean um are there hard philosophical problems to

there hard philosophical problems to which one might hope there's an

which one might hope there's an objective answer which we haven't

objective answer which we haven't uh

uh uh which maybe there's no agreement on

uh which maybe there's no agreement on yet I think that's true but your

yet I think that's true but your question was specifically about

question was specifically about logic

logic [Music]

[Music] um what happens when aliens land

um what happens when aliens land I uh I'm

not I I don't know obviously however let me give you an analogy which I think is

me give you an analogy which I think is telling and let's come back to the Asian

telling and let's come back to the Asian traditions in philosophy

traditions in philosophy again uh a lot of Western

again uh a lot of Western philosophers have thought that um

philosophers have thought that um different cultures reason differently

different cultures reason differently and in fact the way that the

and in fact the way that the Asian Traditions reasoned was um

Asian Traditions reasoned was um wrong you know so Arabic reasoning is

wrong you know so Arabic reasoning is just you know bad bad reasoning Indian

just you know bad bad reasoning Indian reasoning is bad reasoning Chinese

reasoning is bad reasoning Chinese reasoning is bad reasoning um that just

reasoning is bad reasoning um that just seems to me to be crazy why was it why

seems to me to be crazy why was it why was that thought made in the first place

was that thought made in the first place was just racially motivating yes oh it

was just racially motivating yes oh it it's a product of

it's a product of colonialism look I mean the West has

colonialism look I mean the West has taken

taken over Asian countries you know I don't

over Asian countries you know I don't think the Middle East is really Asian I

think the Middle East is really Asian I mean it's it's as much Western as you

mean it's it's as much Western as you know Russia Western Russia

know Russia Western Russia um but often it gets sort of categorized

um but often it gets sort of categorized as Asian um and there was a book by S

as Asian um and there was a book by S where he Co this term asianism which is

where he Co this term asianism which is where you devalue the culture of

where you devalue the culture of something you want to take over so you

something you want to take over so you want you move in you want to conquer it

want you move in you want to conquer it you want to take its resources you want

you want to take its resources you want to subjugate its people um you do that

to subjugate its people um you do that by force but also what you do is devalue

by force but also what you do is devalue their way of

their way of thinking so yes when when asianism was

thinking so yes when when asianism was um employed as it as by the Western

um employed as it as by the Western imperialist countries this was part of

imperialist countries this was part of it now

um I I've read a lot of texts from the Asian traditions in Translation because

Asian traditions in Translation because I I can't read the languages and the

I I can't read the languages and the good philosophers from those Traditions

good philosophers from those Traditions reason exactly the way that I do

reason exactly the way that I do um

um so uh it's not as though you know the

so uh it's not as though you know the different Traditions have different ways

different Traditions have different ways of reasoning they think of different

of reasoning they think of different arguments sure but when they reason they

arguments sure but when they reason they reason much the same way that I do as a

reason much the same way that I do as a philosopher as a a western train

philosopher as a a western train philosopher okay now maybe martians are

philosopher okay now maybe martians are different who knows but uh I doubt it

different who knows but uh I doubt it somehow uh so I think that

somehow uh so I think that um they're very light

um they're very light [Music]

[Music] um to reason the same way that we reason

um to reason the same way that we reason it's so interesting to me because if

it's so interesting to me because if that is the case then I would Place

that is the case then I would Place logic higher than even something as

logic higher than even something as rigorous as math and physics because as

rigorous as math and physics because as you've seen with foundations of physics

you've seen with foundations of physics and math now even math is pretty

and math now even math is pretty subjective you brought up the axioms

subjective you brought up the axioms ukian geometry parallel postulate and

ukian geometry parallel postulate and then set theory aximum of choice

then set theory aximum of choice depending on the framework you subscribe

depending on the framework you subscribe to math can be quite subjective so if

to math can be quite subjective so if aliens were to land on Earth using the

aliens were to land on Earth using the same analogy there might not be any

same analogy there might not be any mutual agreement on Geometry because you

mutual agreement on Geometry because you might have ascribed to a very different

might have ascribed to a very different set of axioms same applies to

set of axioms same applies to foundations of physics but you're making

foundations of physics but you're making the case that logic is above that as an

the case that logic is above that as an objective no I think I think don't don't

objective no I think I think don't don't be so fast look

um we think now that ukle geometry is a perfectly good geometric system okay

perfectly good geometric system okay when we examine it we know now there are

when we examine it we know now there are lots of pure geometries

lots of pure geometries okay

okay now it used to be thought that when you

now it used to be thought that when you appli geometry to understand the space

appli geometry to understand the space uh or time ukle and geometry was the

uh or time ukle and geometry was the right geometry we now think that's wrong

right geometry we now think that's wrong okay but we don't think the pure

okay but we don't think the pure mathematics is wrong we just think we

mathematics is wrong we just think we got the wrong system so we're inventing

got the wrong system so we're inventing new systems of um mathematics all the

new systems of um mathematics all the time and physicists will use whichever

time and physicists will use whichever mathematical system seems to work best

mathematical system seems to work best for their purposes um

for their purposes um and it may well be that when the aliens

and it may well be that when the aliens land they'll have discovered new

land they'll have discovered new mathematical systems that we haven't

mathematical systems that we haven't found yet just as we have mathematical

found yet just as we have mathematical systems now the ancient Greeks didn't

systems now the ancient Greeks didn't know about but that doesn't mean that uh

know about but that doesn't mean that uh there's a relativity about this we can

there's a relativity about this we can you know engage with their math if they

you know engage with their math if they Dain to explain to us um we can engage

Dain to explain to us um we can engage with those and no doubt understand those

with those and no doubt understand those just the way in which you know we may

just the way in which you know we may have mathematical systems they haven't

have mathematical systems they haven't understood and in principle the same is

understood and in principle the same is true physics we have new physical

true physics we have new physical theories now and we can understand the

theories now and we can understand the physics

physics of 1500 and if you took someone from

of 1500 and if you took someone from 1500 and educated them now out modern

1500 and educated them now out modern physics they' understand them um you

physics they' understand them um you know there's uh so changes everywhere

know there's uh so changes everywhere and they may have thought of things that

and they may have thought of things that we haven't thought of just like we've

we haven't thought of just like we've thought of things that the people in the

thought of things that the people in the 15th century didn't think of but uh that

15th century didn't think of but uh that doesn't show that we can't engage with

doesn't show that we can't engage with these things understand what each of us

these things understand what each of us is doing um because that's you

is doing um because that's you know that's the way that communication

know that's the way that communication with certainly other humans works and

with certainly other humans works and you know probably martians too let me

you know probably martians too let me bring it back to Earth you brought up

bring it back to Earth you brought up Eastern philosophy and Asian

Eastern philosophy and Asian philosophy we need days to talk about

philosophy we need days to talk about this so this is going to be unfair but I

this so this is going to be unfair but I do want to sneak in a couple of

do want to sneak in a couple of questions What attracted you to Eastern

questions What attracted you to Eastern philosophy Buddhist philosophy when your

philosophy Buddhist philosophy when your friend J introduce you to it what was

friend J introduce you to it what was what were the key aspects of it that

what were the key aspects of it that stood out to you and you gravitated

stood out to you and you gravitated towards

towards it um simply that there's a whole Rich

it um simply that there's a whole Rich philosophical that I was going to say

philosophical that I was going to say tradition but that's wrong I mean there

tradition but that's wrong I mean there are many Asian Traditions Asian

are many Asian Traditions Asian philosophy is just silly there are many

philosophy is just silly there are many Asian philosophies just like there are

Asian philosophies just like there are many Western philosophies but uh I came

many Western philosophies but uh I came to see thanks to you know friendship

to see thanks to you know friendship with Jay that the philosophical Theory

with Jay that the philosophical Theory that people in China and India and

that people in China and India and doubtless other places have come up with

doubtless other places have come up with are just as rich and

are just as rich and fascinating as those that I was sort of

fascinating as those that I was sort of familiar with in the west which is not

familiar with in the west which is not to say that I mean truth isn't always

to say that I mean truth isn't always another matter you know um but first of

another matter you know um but first of all

all um what philosophers do is try and

um what philosophers do is try and understand theories uh and then you can

understand theories uh and then you can start to wonder about whether or not

start to wonder about whether or not they're true

they're true and there was just so much the the the

and there was just so much the the the East was just so rich in a way that the

East was just so rich in a way that the West Was Rich to me and I knew nothing

West Was Rich to me and I knew nothing about it so I decided to go and find out

about it so I decided to go and find out I do want to get a very small teaser

I do want to get a very small teaser into one of these worlds of philosophy

into one of these worlds of philosophy and I know it's impossible because you

and I know it's impossible because you can spend days talking about this and I

can spend days talking about this and I also agree that this is not entirely

also agree that this is not entirely Eastern philosophy you had Alexus Minong

Eastern philosophy you had Alexus Minong but I do want to bring up nism which is

but I do want to bring up nism which is something that did permeate a lot of

something that did permeate a lot of Buddhist philosophy a lot of easn

Buddhist philosophy a lot of easn philosophy there was shata the madaka

philosophy there was shata the madaka tradition nagarjun who had spoken a lot

tradition nagarjun who had spoken a lot about nothingness so I do want to

about nothingness so I do want to provide a quick teaser what is

provide a quick teaser what is everything what is nothingness what does

everything what is nothingness what does that

mean okay let's set nothingness aside for the moment okay let's talk about

for the moment okay let's talk about nism um so nism is the view that some

nism um so nism is the view that some things don't exist and it's not a crazy

things don't exist and it's not a crazy view look uh I used to be a Christian I

view look uh I used to be a Christian I believe that God existed now I believe

believe that God existed now I believe that God is something that doesn't exist

that God is something that doesn't exist Perfectly Natural or I can want to buy

Perfectly Natural or I can want to buy you something that I discover doesn't

you something that I discover doesn't exist maybe um an actual picture of

exist maybe um an actual picture of Sherlock Holmes but that's a description

Sherlock Holmes but that's a description of something that doesn't exist um and

of something that doesn't exist um and in fact nanism has been regarded as a

in fact nanism has been regarded as a crazy view since Russell and Quin

crazy view since Russell and Quin attacked it early in the 20th century

attacked it early in the 20th century but nism has been absolutely standard in

but nism has been absolutely standard in the history of Western

the history of Western philosophy you look at uh Latin

philosophy you look at uh Latin philosophy Arabic philosophy all these

philosophy Arabic philosophy all these guys subscribe to the view that some

guys subscribe to the view that some things don't exist it's a very common

things don't exist it's a very common sense view so uh it's the view it's

sense view so uh it's the view it's Wine's view that everything exists which

Wine's view that everything exists which is the crazy View and his arguments are

is the crazy View and his arguments are not great arguments it must be

not great arguments it must be said so we we're starting to see the

said so we we're starting to see the pendulum swinging back towards a much

pendulum swinging back towards a much more common sense view

more common sense view nanism okay so that's that's nanism now

nanism okay so that's that's nanism now nothingness

um is a very special [Music]

[Music] object

object um I think it's a non-existent

um I think it's a non-existent object so nism is certainly

object so nism is certainly relevant lots of philosophers have

relevant lots of philosophers have regarded discussion of nanism sorry of

regarded discussion of nanism sorry of discussions of nothing as completely

discussions of nothing as completely confused I think they're

confused I think they're wrong

wrong um why it would take us another couple

um why it would take us another couple of hours to talk about but I do think

of hours to talk about but I do think nothingness is an important concept and

nothingness is an important concept and in fact you know so many Western

in fact you know so many Western philosophers have also thought this um

philosophers have also thought this um you know Mett Hegel Iger sat and and in

you know Mett Hegel Iger sat and and in the East um nishitani ntia

the East um nishitani ntia um uh so talking about nothingness is

um uh so talking about nothingness is not the province of Asian philosophy you

not the province of Asian philosophy you find it in many Great Western

find it in many Great Western philosophers too now what they say about

philosophers too now what they say about it what it is what its properties are

it what it is what its properties are that's highly contentious and because

that's highly contentious and because you're reasoning about a very strange

you're reasoning about a very strange object it's going to be very hard to get

object it's going to be very hard to get straight of

straight of that's the topic of my next book that's

that's the topic of my next book that's a plug okay um now uh do you find it in

a plug okay um now uh do you find it in some of the Asian Traditions yes

some of the Asian Traditions yes absolutely uh it has nothing to do with

absolutely uh it has nothing to do with emptiness

emptiness shata um which means something quite

shata um which means something quite different Chata in Indian Buddhism is

different Chata in Indian Buddhism is the thought that everything is what it

the thought that everything is what it is only in relation to other things so

is only in relation to other things so nothing has a self- nature the Sans word

nothing has a self- nature the Sans word is Shava so to say that something is

is Shava so to say that something is empty is to say that it has no intrinsic

empty is to say that it has no intrinsic nature and the Buddhist mamic view is

nature and the Buddhist mamic view is that nothing has self- nature everything

that nothing has self- nature everything is empty which you can see has got

is empty which you can see has got nothing to do with

nothing to do with nothingness the trouble is that once

nothingness the trouble is that once Buddhism goes into

Buddhism goes into China it gets tangled up with Daoism and

China it gets tangled up with Daoism and then you do

then you do find discussions of nothingness which is

find discussions of nothingness which is sometimes used described by the word

sometimes used described by the word chunat

chunat emptiness um and certainly in a number

emptiness um and certainly in a number of the Chinese Buddhist Traditions you

of the Chinese Buddhist Traditions you get a discussion of nothingness

get a discussion of nothingness particularly in Zen now I mentioned

particularly in Zen now I mentioned Nishida just now he's a Japanese

Nishida just now he's a Japanese philosopher 20th century probably the

philosopher 20th century probably the most important Japanese philosopher of

most important Japanese philosopher of the 20th

the 20th century

century um he's trying to understand Western

um he's trying to understand Western text is probably the first major

text is probably the first major Japanese philosoph to do so but he

Japanese philosoph to do so but he practices Zen Buddhism so he draws on

practices Zen Buddhism so he draws on Zen

Zen philosophy and one of the core aspects

philosophy and one of the core aspects of his thinking is precisely absolute

of his thinking is precisely absolute nothingness which he's taking over from

nothingness which he's taking over from Zen thought uh and he mixes I mean he he

Zen thought uh and he mixes I mean he he works on this concept and tries to sort

works on this concept and tries to sort of articulate it using thoughts from

of articulate it using thoughts from Hegel and haiger and is he's a

Hegel and haiger and is he's a fascinating philosopher but

fascinating philosopher but it it's certainly there present in this

it it's certainly there present in this thought it's a central notion of his

thought it's a central notion of his thought but then it is of you know take

thought but then it is of you know take some favor or Western philosophers s

some favor or Western philosophers s heiger Hegel um so

heiger Hegel um so uh the connection with nanism is is

uh the connection with nanism is is there but it's not a very Central One it

there but it's not a very Central One it must be said um but it's played a major

must be said um but it's played a major role in a number of important

role in a number of important philosophers both East and West so you

philosophers both East and West so you you shouldn't just identified this with

you shouldn't just identified this with some strange Asian

some strange Asian view yeah I intended this question to be

view yeah I intended this question to be a teaser because and you have given a

a teaser because and you have given a wonderful teaser because I can think of

wonderful teaser because I can think of 20 more followup questions you brought

20 more followup questions you brought up coin on what there is and what exists

up coin on what there is and what exists what doesn't exist with nothingness I

what doesn't exist with nothingness I guess there are questions about

guess there are questions about grounding and like the ontological

grounding and like the ontological Primitive layers as well so many worlds

Primitive layers as well so many worlds that you could explore this is

that you could explore this is definitely a very interesting field it

definitely a very interesting field it deserves an entire day on its own so I

deserves an entire day on its own so I want to be appreciated of that let's

want to be appreciated of that let's start moving into some of our closing

start moving into some of our closing questions but before we go there I would

questions but before we go there I would love it if you can interpret what

love it if you can interpret what Masterpiece I've built with the Lego

Masterpiece I've built with the Lego what do you think this

is okay I'm going to fail the r test it's an

it's an object

um maybe the front of a building with a flower pot or something outside the

flower pot or something outside the front door I don't know I mean sorry is

front door I don't know I mean sorry is an object that looks like a building

an object that looks like a building therefore it must be a building that's

therefore it must be a building that's logic yeah I think it looks like a

logic yeah I think it looks like a building as well let's move but it is

building as well let's move but it is winking it is it's a new age building

winking it is it's a new age building modern architecture actually it might be

modern architecture actually it might be something else the other way up what

something else the other way up what does it look

does it look like it looks like oh okay uh when when

like it looks like oh okay uh when when I was a kid they had Fairgrounds I don't

I was a kid they had Fairgrounds I don't they probably still do and there was

they probably still do and there was something called um ring the

something called um ring the bell yeah so you you have a mallet and

bell yeah so you you have a mallet and you hit a something and it propels the

you hit a something and it propels the thing up and you have to sort of shoot

thing up and you have to sort of shoot it up and if it goes right to the top it

it up and if it goes right to the top it rings a bell and you get a prize okay

rings a bell and you get a prize okay looks like

looks like that you know we still have it D Busters

that you know we still have it D Busters on Time Square you still have you know

on Time Square you still have you know what this is it if you I'm sure if I

what this is it if you I'm sure if I change that Le again you're going to see

change that Le again you're going to see a different and then logic has gone out

a different and then logic has gone out of the question because your inferences

of the question because your inferences are dependent on which angle you're

are dependent on which angle you're looking from okay let's move into a

looking from okay let's move into a closing questions what are some books

closing questions what are some books movies role models that have strongly

movies role models that have strongly influenced you in your life

um I'm not a great movie [Music]

[Music] girl

girl uh the ones I like best the ones with

uh the ones I like best the ones with philosophical themes ditto fiction I'm

philosophical themes ditto fiction I'm not a great fiction reader I read a lot

not a great fiction reader I read a lot of

of philosophy

philosophy and uh look I've read many great

and uh look I've read many great philosophers east and west and I think

philosophers east and west and I think I've learned something from all of them

I've learned something from all of them I don't always agree with them in fact I

I don't always agree with them in fact I don't usually agree with them but what

don't usually agree with them but what makes them a great philosopher is they

makes them a great philosopher is they have

have insight and you can learn from their

insight and you can learn from their their gleams of insight even if you

their gleams of insight even if you think they're

think they're wrong so you know what are my Phil cal

wrong so you know what are my Phil cal book I can't answer because

book I can't answer because uh i' I've learned from so many great

uh i' I've learned from so many great philosophers I'm going to keep putting

philosophers I'm going to keep putting you on the spot here we've spoken about

you on the spot here we've spoken about the works of

the works of some great philosophers we have today we

some great philosophers we have today we have referenced Aristotle frager Hegel

have referenced Aristotle frager Hegel haiger beron Russell wienstein Quin

haiger beron Russell wienstein Quin there are some that we didn't reference

there are some that we didn't reference explicitly alluded to their work livess

explicitly alluded to their work livess Lewis Hume aquinus Thomas hob there are

Lewis Hume aquinus Thomas hob there are so many and those were all Western

so many and those were all Western philosophers you've missed out all the

philosophers you've missed out all the Eastern ones all the Eastern

Eastern ones all the Eastern philosophers well yeah I think the list

philosophers well yeah I think the list could just keep going on and on and on

could just keep going on and on and on so I'm going to ask you a deliberately

so I'm going to ask you a deliberately difficult unfair question but who do you

difficult unfair question but who do you think was one philosopher that had the

think was one philosopher that had the most impact on you the most influential

most impact on you the most influential philosopher for you and

why that's really hard I mean it's it's sort of unfair

to name anyone philosopher I mean at various times uh I've read different

various times uh I've read different philosophers and they've impacted on my

philosophers and they've impacted on my thinking at those times so you know when

thinking at those times so you know when when I started doing philosophy I read

when I started doing philosophy I read was reading Russell and carap those had

was reading Russell and carap those had a big impact on my think and Quin um

a big impact on my think and Quin um later on I started to read um some of

later on I started to read um some of the medieval

the medieval logicians um

logicians um um Canton Hegel Marx big big time

um Canton Hegel Marx big big time influence on my political philosophy um

influence on my political philosophy um brickenstein of course

brickenstein of course um in the West in the East

um Nisha Doan Naga Juna I mean I you know taken a lot from n junr over the

know taken a lot from n junr over the years um and I'm I'm only just starting

years um and I'm I'm only just starting to sort of delve into the realm of

to sort of delve into the realm of Arabic philosophy uh something I've only

Arabic philosophy uh something I've only started to read about think about in the

started to read about think about in the last five or six years but imman sin is

last five or six years but imman sin is a great philosopher

obviously and it's not an area I know enough about yet to talk about the other

enough about yet to talk about the other philosophers in that area but no doubt

philosophers in that area but no doubt you know I hope to learn from them in

you know I hope to learn from them in due course so you know different

due course so you know different philosophers had a different impact on

philosophers had a different impact on me at different stages my philosophical

me at different stages my philosophical Journey as it were and it' be wrong to

Journey as it were and it' be wrong to say that any one of those has been more

say that any one of those has been more important than others you mentioned the

important than others you mentioned the difficulty of the question this

difficulty of the question this interview has been structured like the

interview has been structured like the fuzzy logic Glide path we started with

fuzzy logic Glide path we started with simple questions like what is logic and

simple questions like what is logic and you might have thought this is going to

you might have thought this is going to be a breeze but now we at the end zone

be a breeze but now we at the end zone the end game and this is going to be

the end game and this is going to be difficult questions for you I hope

difficult questions for you I hope you're ready last two questions you

you're ready last two questions you mentioned a lot of influential

mentioned a lot of influential philosophers from one influential

philosophers from one influential philosopher to the one right in front of

philosopher to the one right in front of me how do you want to be remembered what

me how do you want to be remembered what would we like you your legacy to be I'll

would we like you your legacy to be I'll leave that to

posterity Beyond philosophy on a let's say on a personal level is there some

say on a personal level is there some memory you want to leave

memory you want to leave behind I hope that the people who knew

behind I hope that the people who knew me love

me I'm sure they do and you underplaying and you spoke out postive

and you spoke out postive you're underplaying your influence and

you're underplaying your influence and impact in the world of

impact in the world of philosophy I think it's been immense but

philosophy I think it's been immense but if you ask me personally I think your

if you ask me personally I think your biggest career highlight has to be being

biggest career highlight has to be being one of the background dancers in the

one of the background dancers in the ballroom scene The Beatles movie Magical

ballroom scene The Beatles movie Magical Mystery to if I was you I would plug

Mystery to if I was you I would plug that top of the resume that is the

that top of the resume that is the greatest okay final question if you

greatest okay final question if you could see me in the bloody movie I'm one

could see me in the bloody movie I'm one of the pleb stuck at the back just being

of the pleb stuck at the back just being there in the presence of The Beatles I

there in the presence of The Beatles I think it's the greatest C highlight

think it's the greatest C highlight goinging to me final question we had the

goinging to me final question we had the top of this Glide path Hamlet had once

top of this Glide path Hamlet had once said there are more things in Heaven and

said there are more things in Heaven and Earth ratio than are dreamt of in your

Earth ratio than are dreamt of in your philosophy let's talk about everything

philosophy let's talk about everything else on Heaven and Earth that's I want

else on Heaven and Earth that's I want to ask you the most difficult question I

to ask you the most difficult question I guess or maybe the easiest the biggest

guess or maybe the easiest the biggest question of all about meaning and about

question of all about meaning and about purpose

purpose what is the meaning of life Grand

priest this may be one of those questions where you

may be one of those questions where you really have to sort of start worrying

really have to sort of start worrying about what you asking about when you ask

about what you asking about when you ask about the meaning of

I taught a course last semester on an old book by Tom Nagel called um the view

old book by Tom Nagel called um the view from nowhere and it's a very interesting

from nowhere and it's a very interesting chapter last chapter of that book about

chapter last chapter of that book about this question and I think he get

this question and I think he get something absolutely

something absolutely right

um in fact I mean I want to write a paper about it when I get the

paper about it when I get the time but what he argues is that from a

time but what he argues is that from a cosmic perspective nothing has has any

meaning so you know I have no religion I believe that

know I have no religion I believe that in the end

in the end the physical Cosmos will keep on

the physical Cosmos will keep on expanding

expanding forever and end with a density so close

forever and end with a density so close to zero that it makes no difference from

to zero that it makes no difference from that point of view anything that's

that point of view anything that's happened before is irrelevant be no

happened before is irrelevant be no sentience no one to remember anything So

sentience no one to remember anything So objectively

objectively speaking from this third person

speaking from this third person perspective supposing you're sort of

perspective supposing you're sort of flying the wall watching this whole

flying the wall watching this whole process life has no meaning now of

process life has no meaning now of course you cannot live like

course you cannot live like that so from the

that so from the subjective

subjective perspective things are important and

perspective things are important and it's important that you figure out

it's important that you figure out what's

what's important uh you couldn't live otherwise

in the end you probably figure out what's important for

what's important for yourself I mean for me doing philosophy

yourself I mean for me doing philosophy is

is important

important um I'd like to leave the world a better

um I'd like to leave the world a better place and I find it that's

place and I find it that's important U my relationships with those

important U my relationships with those close to

close to me my wife my students my kids is

me my wife my students my kids is important to

important to me um so those are the things I value

me um so those are the things I value those are the things which motivate me

those are the things which motivate me to act on a day-to-day

to act on a day-to-day basis so that's for me that's the

basis so that's for me that's the meaning of

meaning of life now um I've said objectively

life now um I've said objectively there's no meaning subjectively there is

there's no meaning subjectively there is a

a meaning uh and you might say well okay

meaning uh and you might say well okay there's just two meanings of um meaning

there's just two meanings of um meaning of life an objective meaning and a

of life an objective meaning and a subjective meaning and so you know you

subjective meaning and so you know you give them different answers where where

give them different answers where where that gets really interesting is that the

that gets really interesting is that the world does not fall neatly apart into

world does not fall neatly apart into these two things and there's a sense in

these two things and there's a sense in which the objective and the subjective

which the objective and the subjective inter interact and engage with each

inter interact and engage with each other that's one of the fascinating

other that's one of the fascinating things of Nagel's book that you can't

things of Nagel's book that you can't have one without the other you can't

have one without the other you can't have the objective view because I look

have the objective view because I look at the objective view from my subjective

at the objective view from my subjective position okay um and you can't have a

position okay um and you can't have a merely subjective view because um I'm an

merely subjective view because um I'm an object in this third person perspective

object in this third person perspective so the the first person view and the

so the the first person view and the third person view are dickly entangled

third person view are dickly entangled so you can't say well objectively it's

so you can't say well objectively it's this subjectively it's that because they

this subjectively it's that because they they engage with each other in a certain

they engage with each other in a certain way

way um and I'm inclined to say the world is

um and I'm inclined to say the world is contradictory in that way the world must

contradictory in that way the world must be both subjective and objective at the

be both subjective and objective at the same time and is that a contradiction

same time and is that a contradiction yes so that's what I want to write about

yes so that's what I want to write about when I next when I get the time and I'm

when I next when I get the time and I'm sorry uh you wanted a nice simple answer

sorry uh you wanted a nice simple answer and I've given you something absolutely

and I've given you something absolutely horrendous wanted you to solve it for me

horrendous wanted you to solve it for me but I like it I like the fact that the

but I like it I like the fact that the meaning of life there's a contradiction

meaning of life there's a contradiction there because that embodies this

there because that embodies this conversation perfect encapsulates it in

conversation perfect encapsulates it in in the best way possible Professor if

in the best way possible Professor if people want to find you find out more

people want to find you find out more about your work read some of your books

about your work read some of your books find out some of your papers what is the

find out some of your papers what is the best way to find you um probably just go

best way to find you um probably just go to my website uh which is not difficult

to my website uh which is not difficult to remember it's gra priest. net Grand

to remember it's gra priest. net Grand priest is all one string and it's all

priest is all one string and it's all lowercase the website is the way

lowercase the website is the way Professor I cannot stress enough how

Professor I cannot stress enough how much of an honor and a privilege it was

much of an honor and a privilege it was for me thank you so much well thank you

for me thank you so much well thank you it's been a fascinating conversation

it's been a fascinating conversation [Music]

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Logic, Philosophy & Paradoxes ft. Graham Priest | Know Time #93