Plato on KnowledgePlato on Knowledge

PlatoPlato 429-347 BC429-347 BC Student of Socrates (469-399)Student of Socrates (469-399) Teacher of Aristotle (384-322)Teacher of Aristotle (384-322) Founded ‘Academy’Founded ‘Academy’ Wrote DialoguesWrote Dialogues

TheaetetusTheaetetus RepublicRepublic MenoMeno

TheaetetusTheaetetus A late treatment of knowledgeA late treatment of knowledge Dismisses two possibilities for knowledgeDismisses two possibilities for knowledge

PerceptionPerception True beliefTrue belief

Proposes: True Belief with an AccountProposes: True Belief with an Account To know X is to truly believe X To know X is to truly believe X andand to have an to have an

account of Xaccount of X But what is an account? Justification for the But what is an account? Justification for the

belief?belief?

TheaetetusTheaetetus First possibility: an account is an First possibility: an account is an

analysis of how X is composed of analysis of how X is composed of simpler partssimpler parts So no simple thing can be known?So no simple thing can be known?

Reject this ideaReject this idea

TheaetetusTheaetetus Second possibility: an account is a Second possibility: an account is a

catalogue of the component parts catalogue of the component parts But you can list the parts of a chariot But you can list the parts of a chariot

without having an understanding of the without having an understanding of the chariot itself.chariot itself. Reject this ideaReject this idea

TheaetetusTheaetetus Third possibility: an account is an Third possibility: an account is an

identification of the distinguishing identification of the distinguishing characteristiccharacteristic To know X about the sun is for X to be a To know X about the sun is for X to be a

true belief and you can identify the sun true belief and you can identify the sun as, say, the brightest object in the skyas, say, the brightest object in the sky

But this means there is always something But this means there is always something else to know before you can know any Xelse to know before you can know any X

Reject this ideaReject this idea

TheaetetusTheaetetus All possibilities are eliminated.All possibilities are eliminated.

AporiaAporia again? again? Plato has another theory from previous Plato has another theory from previous

dialoguesdialogues

The Theory of the FormsThe Theory of the Forms There is a realm of real things that are There is a realm of real things that are

both non-physical and non-mentalboth non-physical and non-mental Things in this realm are the ‘Forms’ (Things in this realm are the ‘Forms’ (ideaideas s

in Greek) of things in the physical realmin Greek) of things in the physical realm Things in the physical realm are what they Things in the physical realm are what they

are because they are in some way are because they are in some way connected to their Formsconnected to their Forms

We can know things only through We can know things only through ‘acquaintance’ with their Forms‘acquaintance’ with their Forms

The Theory of the FormsThe Theory of the Forms Forms explain the possibility of general Forms explain the possibility of general

termsterms We can call many things by one nameWe can call many things by one name

All things which are dogs we can call All things which are dogs we can call a doga dog. . There must be something which is:There must be something which is:

1.1.Common to all things called by a general termCommon to all things called by a general term2.2.Distinctive of all those thingsDistinctive of all those things

This thing isThis thing is1.1.Not physical – not all dogs have any physical traitNot physical – not all dogs have any physical trait2.2.Recognisable by us – but Recognisable by us – but not not by our sensesby our senses

The Theory of the FormsThe Theory of the Forms Forms explain the possibility of Forms explain the possibility of

judgementjudgement All judgement is a type of comparingAll judgement is a type of comparing ‘‘This is a dog’ means I am comparing ‘this’ This is a dog’ means I am comparing ‘this’

to some standard of dogginessto some standard of dogginess The standard can’t be another dog – else I have The standard can’t be another dog – else I have

to first judge that that is a dog, and so onto first judge that that is a dog, and so on The standard can’t be my The standard can’t be my idea idea of a dog – it is the of a dog – it is the

idea of a dog only because it is judged to idea of a dog only because it is judged to represent dogs accurately. So I still need to represent dogs accurately. So I still need to judge judge itsits dogginess; and so on. dogginess; and so on.

The Theory of the FormsThe Theory of the Forms Forms explain the possibility of judgementForms explain the possibility of judgement

The standard of ‘dog’ can’t be physical or The standard of ‘dog’ can’t be physical or mentalmental

It is It is metaphysicalmetaphysical It is that It is that in virtue of whichin virtue of which

1.1. All things properly called ‘dog’ are properly so All things properly called ‘dog’ are properly so calledcalled

2.2. Only things properly called ‘dog’ are properly so Only things properly called ‘dog’ are properly so calledcalled

We call it the Form of dog, or dog-in-itself, …We call it the Form of dog, or dog-in-itself, …

The Theory of the FormsThe Theory of the Forms How do Forms relate to their How do Forms relate to their

particulars?particulars?1. Transcendence: there is far more to

the Forms than the particular things which fall under them

2. Immanence: the Forms are present in their particulars, but not in a way that we can perceive through our senses

The Theory of the FormsThe Theory of the Forms How do we come to know of them?How do we come to know of them?

1.1. Not Not by our external senses by our external senses (perception)(perception)

2.2. NotNot by our internal sense (awareness) by our internal sense (awareness)3.3. But by But by intellectual perception intellectual perception or or

awareness of the awareness of the understandingunderstanding(Whatever those might be)(Whatever those might be)

The Theory of the FormsThe Theory of the Forms Who is capable of knowing them?Who is capable of knowing them?

We are all able to use the term ‘dog’ We are all able to use the term ‘dog’ correctly,correctly, So we are all ‘intellectually aware’ of the Form of So we are all ‘intellectually aware’ of the Form of

DogDog Dog is the Form of a mundane thing – it is a Dog is the Form of a mundane thing – it is a

‘lower’ Form‘lower’ Form ‘‘Higher’ Forms are of things such as Higher’ Forms are of things such as

Triangle, Courage, Equal, Noble, …Triangle, Courage, Equal, Noble, … Only those trained as intellectuals can ‘perceive Only those trained as intellectuals can ‘perceive

these in their understanding’these in their understanding’

How we KnowHow we Know How do we come to know the higher Forms?How do we come to know the higher Forms?

Plato gives an example in the Plato gives an example in the MenoMeno A slave is taught to double a squareA slave is taught to double a square

Slave thinks he knows but gives the wrong answer Slave thinks he knows but gives the wrong answer at first before Socrates begins to question himat first before Socrates begins to question him

This also shows the value of This also shows the value of elenchuselenchus Socrates then gets the slave to give the right Socrates then gets the slave to give the right

answer answer Since the slave only answered questions, he must Since the slave only answered questions, he must

have have knownknown how to double a square already how to double a square already

The Allegory of the CaveThe Allegory of the Cave What is the difference between how What is the difference between how

normal people see the world and normal people see the world and how philosophers see it?how philosophers see it?

The Objects of The Objects of KnowledgeKnowledge

Only the Forms are objects of real knowledgeOnly the Forms are objects of real knowledge They are permanent, unchanging, always trueThey are permanent, unchanging, always true

What is learnt through the senses is ‘opinion’What is learnt through the senses is ‘opinion’ It is impermanent, changeable, sometimes true It is impermanent, changeable, sometimes true

and sometimes notand sometimes not

Plato is contradicted by Aristotle, as we shall Plato is contradicted by Aristotle, as we shall seesee