phil 2002 wits_plato

PHIL 2002 ANCIENT PHILOSOPHY

John [email protected]

• You’ve heard, no doubt, that “knowledge is justified true belief”.

• When do you suppose “they” came up with that?



• Around 427 - 347 BC. And that’s still the standard definition.Talk about getting it right.

• And who do you suppose said it…?



• Around 427 - 347 BC. And that’s still the standard definition.Talk about getting it right.

•Plato “The safest general characterization of the European philosophical tradition is that it consists of a series of footnotes to Plato.” — A N Whitehead

• Unclear how much of Plato’s work is originally his own as opposed to Socrates’.

• ‘The Socratic Method’ or elenchus: Plato’s books, consist entirely of dialogue, with the chief character as Plato’s mentor Socrates, who, through persistent questioning, leads his interlocutors to a philosophical conclusion. Socrates describes himself as merely a midwife, helping his interlocutors birth their own ideas.

PLATO

Socrates was executed in 399 BC on charges of ‘corrupting the youth’.

• Four sections we will look at:

• The Cave

• The Line

• The Forms

• Theaetetus (Epistemology)

PLATO

Behold! human beings living in a underground den [cave], which has a mouth open towards the light and reaching all along the den; here they have been from their childhood, and have their legs and necks chained so that they cannot move, and can only see before them, being prevented by the chains from turning round their heads. Above and behind them a fire is blazing at a distance, and between the fire and the prisoners there is a raised way; and you will see, if you look, a low wall built along the way, like the screen which marionette players have in front of them, over which they show the puppets.

And do you see, I said, men passing along the wall carrying all sorts of vessels, and statues and figures of animals made of wood and stone and various materials, which appear over the wall? Some of them are talking, others silent.

Like ourselves, I replied; and they see only their own shadows, or the shadows of one another, which the fire throws on the opposite wall of the cave?

PLATO — THE CAVE

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Veldkamp, Gabriele. Zukunftsorientierte Gestaltung informationstechnologischer Netzwerke im Hinblick auf die Handlungsfähigkeit des Menschen. Aachener Reihe Mensch und Technik, Band 15, Verlag der Augustinus Buchhandlung, Aachen 1996, Germany

The Cave

Source: Wikimedia Commons

True, he said; how could they see anything but the shadows if they were never allowed to move their heads?

And if they were able to converse with one another, would they not suppose that they were naming what was actually before them?

And suppose once more, that he is reluctantly dragged up a steep and rugged ascent, and held fast until he’s forced into the presence of the sun himself, is he not likely to be pained and irritated? When he approaches the light his eyes will be dazzled, and he will not be able to see anything at all of what are now called realities. … Imagine once more, I said, such an one coming suddenly out of the sun to be replaced in his old situation; would he not be certain to have his eyes full of darkness?

PLATO — THE CAVE

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And if there were a contest, and he had to compete in measuring the shadows with the prisoners who had never moved out of the den, while his sight was still weak, and before his eyes had become steady (and the time which would be needed to acquire this new habit of sight might be very considerable) would he not be ridiculous? Men would say of him that up he went and down he came without his eyes.

PLATO — THE CAVE

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This entire allegory, I said, you may now append… to the previous argument; the prison-house is the world of sight, the light of the fire is the sun, and you will not misapprehend me if you interpret the journey upwards to be the ascent of the soul into the intellectual world according to my poor belief, which, at your desire, I have expressed whether rightly or wrongly God knows. But, whether true or false, my opinion is that in the world of knowledge the idea of good appears last of all, and is seen only with an effort; and, when seen, is also inferred to be the universal author of all things beautiful and right, parent of light and of the lord of light in this visible world, and the immediate source of reason and truth in the intellectual; and that this is the power upon which he who would act rationally, either in public or private life must have his eye fixed.

PLATO — THE CAVE

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But then, if I am right, certain professors of education must be wrong when they say that they can put a knowledge into the soul which was not there before, like sight into blind eyes.

They undoubtedly say this, he replied.

Whereas, our argument shows that the power and capacity of learning exists in the soul already

PLATO — THE CAVE

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Interpretation

• The first thing to point out is that the analogy is often taken to be a mystical one, that is to say, that Plato is claiming that our world is like being in a dark cave, and we live in a world of illusions.

“marionette players have in front of them, over which they show the puppets.”

And that once we leave this cave, this world of illusions, via, say, Philosophy, we come to see the Truth with a capital T. Plato says:

“[In] the world of knowledge the idea of good appears last of all, and is seen only with an effort; and, when seen, is also inferred to be the universal author of all things beautiful and right, parent of light and of the lord of light in this visible world”.

It is apparent that he is referring to a divine principle here — the “parent”, the “lord of light”.

PLATO — THE CAVE

Interpretation

• However, if you read the entire Book (Chapter) you will see that he’s ultimately working towards a political point: namely, noocracy, his position that society should be ruled by Philosophers (rather than democracy or democratically-elected officials).

“the business of us who are the founders of the State will be to compel the best minds to attain that knowledge which we have already shown to be the greatest of all ... they must [then] be made to descend again among the prisoners in the den….

Whereas the truth is that the State in which the rulers are most reluctant to govern is always the best and most quietly governed, and the State in which they are most eager, the worst.”

• Compare this to the Tao Te Ching (48):

“The one who interferes is not qualified to take the world.”

PLATO — THE CAVE

Interpretation

“certain professors of education must be wrong when they say that they can put a knowledge into the soul which was not there before, like sight into blind eyes.”

• In other words, people already know the Truth a priori, they just need to be shown it. And the reference to the Forms occurs in his use of the puppets and the fire and the objects placed before the fire. The objects; the puppets, are the Forms (of physical things); the shadows they cast are the illusions (which we think are the truths: the physical things themselves). But the ultimate Truth is the Sun outside the cave (the Form of the Good). We will see more of this in the Meno.

PLATO — THE CAVE

• Plato holds that there are varying degrees of Truth, which is traditionally referred to as “the Line” or “the Divided Line”.

• In the Republic, Book VI, Plato introduces us to the analogy of the Sun, comparing the Sun to the Form of the Good (i.e. the ultimate or true good). It seems, however, sensible to first talk about the world of appearances, versus the world of illusions, via the Cave Analogy, and then go onto Plato’s taxonomy of metaphysical or epistemological reality/truth.

• In the analogy of the Line, we find Plato divides up the intelligible world into sections; some what we would now call a priori, typically referring to the “Forms”, and some referring to the physical world, what we would call “a posteriori”

PLATO — THE LINE

Now take a line which has been cut into two unequal parts, and divide each of them again in the same proportion, and suppose the two main divisions to answer, one to the visible and the other to the intelligible, and then compare the subdivisions in respect of their clearness and want of clearness, and you will find that the first section in the sphere of the visible consists of images.

Imagine, now, the other section, of which this is only the resemblance, to include the animals which we see, and everything that grows or is made.

Would you not admit that both the sections of this division have different degrees of truth, and that the copy is to the original as the sphere of opinion is to the sphere of knowledge?

Thus: — There are two subdivisions [of the ‘intelligible’ part of the line], in the lower or which the soul uses the figures given by the former division as images; the enquiry can only be hypothetical, and instead of going upwards to a principle descends to the other end; in the higher of the two, the soul passes out of hypotheses, and goes up to a principle which is above hypotheses, making no use of images as in the former case, but proceeding only in and through the ideas themselves.

PLATO — THE LINE

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You are aware that students of geometry, arithmetic, and the kindred sciences assume the odd and the even and the figures and three kinds of angles and the like in their several branches of science; these are their hypotheses, which they and everybody are supposed to know, and therefore they do not deign to give any account of them either to themselves or others; but they begin with them, and go on until they arrive at last, and in a consistent manner, at their conclusion?

And do you not know also that although they make use of the visible forms and reason about them, they are thinking not of these, but of the ideals which they resemble; not of the figures which they draw, but of the absolute square and the absolute diameter, and so on — the forms which they draw or make, … which can only be seen with the eye of the mind?

And of this kind I spoke as the intelligible, although in the search after it the soul is compelled to use hypotheses;…

PLATO — THE LINE

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And when I speak of the other division of the intelligible, you will understand me to speak of that other sort of knowledge which reason herself attains by the power of dialectic,…, and in ideas she ends.

…Knowledge and being, which the science of dialectic contemplates, are clearer than the notions of the arts, as they are termed, which proceed from hypotheses only: these are also contemplated by the understanding, and not by the senses: yet, because they start from hypotheses and do not ascend to a principle, those who contemplate them appear to you not to exercise the higher reason upon them, although when a first principle is added to them they are cognizable by the higher reason. And the habit which is concerned with geometry and the cognate sciences I suppose that you would term understanding and not reason, as being intermediate between opinion and reason.

PLATO — THE LINE

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Now, corresponding to these four divisions, let there be four faculties in the soul — reason answering to the highest, understanding to the second, faith (or conviction) to the third, and perception of shadows to the last — and let there be a scale of them, and let us suppose that the several faculties have clearness in the same degree that their objects have truth.

PLATO — THE LINE

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• The purpose of the Line Analogy is to compare our states of knowing, our epistemological states, rather than metaphysical external states. Whilst the analogy deals with the Forms, only the higher level recognises the Forms themselves rather than their shadows or physical-world representations. In effect, half of our mental reality consists of the Forms; the intelligible realm or the a priori. The lower half consists of things we perceive by means of the senses; the a posteriori. In the upper half, we have understanding and reason. In the lower half, we have illusions, shadows, and physical objects. We have illusion states about illusory things, and we have belief states or faith states about physical things.

PLATO — THE LINE

• The lowest form of reality is illusion or shadow. Then physical objects, which are mere instantiations of the Forms, about which we have beliefs (propositional states or opinions). Above physical objects are the Forms of the objects, the higher reality.

• The distinction between “Understanding” and “Reason” is about whether one perceives hypotheses (theories), with the Understanding, or, whether one perceives the general principles (Forms) which these hypotheses refer to, by means of the Reason. The example given is of geometry. One can understand that x is an isosceles triangle, and be able to prove it with the understanding. But one has not perceived the true One Form of the Isosceles Triangle unless one uses Reason.

PLATO — THE LINE

• Plato believed that we bring knowledge with us into the world, specifically, a priori knowledge of Forms, which may be interpreted in modern epistemology as “types” rather than “tokens”. The idea, roughly speaking, is that you can’t know that x is a triangle unless you first know what a triangle is, a priori. The job of Reason, as Plato explains in the Cave Analogy, is to bring us to an awareness of the Forms, especially the Form of the Good (the “Sun”). The token or material object “partakes” in the Form, and hence shares its properties. For any particular thing (token), there is a corresponding Form (type).

• Plato’s “Forms” doctrine appears in many dialogues, and is never fully expounded in any particular one. The Meno probably contains the clearest statement of his doctrine of Recollection, that is, that we never learn anything, we just are reminded of it by our teachers. This, Plato believed, proved that we are not only reincarnated, but, the fact that we know the Forms, means that prior to our reincarnation, we were living in the realm of the Forms themselves (as spirits, presumably).

PLATO — THE FORMS

From The Sophist

The Stranger: And as classes [Forms] are admitted by us in like manner to be some of them capable and others incapable of intermixture, must not he who would rightly show what kinds will unite and what will not, proceed by the help of science in the path of argument? And will he not ask if the connecting links are universal, and so capable of intermixture with all things; and again, in divisions, whether there are not other universal classes, which make them possible?

The Stranger: Then, surely, he who can divide rightly is able to see clearly one form pervading a scattered multitude, and many different forms contained under one higher form; and again, one form knit together into a single whole and pervading many such wholes, and many forms, existing only in separation and isolation. This is the knowledge of classes which determines where they can have communion [‘partake’] with one another and where not.

PLATO — THE FORMS

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From Phaedo

... Is that idea or essence, which in the dialectical process we define as essence [form] of true existence — whether essence of equality, beauty, or anything else: are these essences, I say, liable at times to some degree of change? or are they each of them always what they are, having the same simple, self-existent and unchanging forms, and not admitting of variation at all, or in any way, or at any time?

They must be always the same, ... the unchanging things [forms] you can only perceive with the mind — they are invisible and are not seen

... Then the soul is more like to the unseen, and the body to the seen? ... were we not saying that the soul too is then dragged by the body into the region of the changeable, and wanders and is confused; the world spins round her, and she is like a drunkard when under their influence? … But when returning into herself she reflects; then she passes into the realm of purity, and eternity, and immortality, and unchangeableness,... then she ceases from her erring ways, and being in communion with the unchanging is unchanging. And this state of the soul is called wisdom?

PLATO — THE FORMS

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From Parmenides (Book about Parmenides by Plato, not Parmenides’ book) I mean such things as hair, mud, dirt, or anything else which is vile and paltry; would you suppose that each of these has an idea [a Form] distinct from the actual objects with which we come into contact, or not?

Certainly not, said Socrates; visible things like these are such as they appear to us, and I am afraid that there would be an absurdity in assuming any idea of them, although I sometimes get disturbed, and begin to think that there is nothing without an idea; ...

Yes, Socrates, said Parmenides... But I should like to know whether you mean that there are certain ideas of which all other things partake, and from which they derive their names; that similars, for example, become similar, because they partake of similarity; and great things become great, because they partake of greatness; and that just and beautiful things become just and beautiful, because they partake of justice and beauty?

Then each individual partakes either of the whole of the idea or else of a part of the idea? Can there be any other mode of participation [partaking]?

PLATO — THE FORMS

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From Parmenides (Book about Parmenides by Plato, not Parmenides’ book)

[Now] do you think that the whole idea is one, and yet, being one, is in each one of the many? Because one and the same thing will exist as a whole at the same time in many separate individuals, and will therefore be in a state of separation from itself.

Then would you like to say, Socrates, that the one idea [form] is really divisible and yet remains one?

... Then in what way, Socrates, will all things participate [partake] in the ideas, if they are unable to participate in them either as parts or wholes?

Indeed, he said, you have asked a question which is not easily answered. Then another idea of greatness now comes into view over and above absolute greatness, and the individuals which partake of it; and then another, over and above all these, by virtue of which they will all be great, and so each idea instead of being one will be infinitely multiplied.

PLATO — THE FORMS

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But may not the ideas, [forms] asked Socrates, be thoughts only, and have no proper existence except in our minds, Parmenides? For in that case each idea may still be one, and not experience this infinite multiplication.And can there be individual thoughts which are thoughts of nothing?

Impossible, he said. The thought must be of something? Yes. Of something which is or which is not? Of something which is. Must it not be of a single something, which the thought recognizes as

attaching to all, being a single form or nature?

PLATO — THE FORMS

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Yes. And will not the something which is apprehended as one and the same in all,

be an idea? From that, again, there is no escape. Then, said Parmenides, if you say that everything else participates in the

ideas, must you not say either that everything is made up of thoughts, and that all things think; or that they are thoughts but have no thought?

The latter view, Parmenides, is no more rational than the previous one. In my opinion, the ideas [forms] are, as it were, patterns fixed in nature, and other things are like them, and resemblances of them — what is meant by the participation of other things in the ideas, is really assimilation to them.

But if, said he, the individual is like the idea, must not the idea also be like the individual, in so far as the individual is a resemblance of the idea?

PLATO — THE FORMS

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From Parmenides (Book about Parmenides by Plato, not Parmenides’ book) And when two things are alike, must they not partake of the same idea?

They must. And will not that of which the two partake, and which makes them alike,

be the idea itself? Certainly. Then the idea cannot be like the individual, or the individual like

the idea; for if they are alike, some further idea of likeness will always be coming to light, and if that be like anything else, another; and new ideas will be always arising, if the idea resembles that which partakes of it?

Quite true. The theory, then that other things participate in the ideas by resemblance,

has to be given up, and some other mode of participation devised?

PLATO — THE FORMS

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From Parmenides (Book about Parmenides by Plato, not Parmenides’ book) It would seem so.

Do you see then, Socrates, how great is the difficulty of affirming the ideas to be absolute?Yes, indeed.

And, further, let me say that as yet you only understand a small part of the difficulty which is involved if you make of each thing a single idea, parting it off from other things.

What difficulty? he said. There are many, but the greatest of all is this: — If an opponent argues that

these ideas, being such as we say they ought to be, must remain unknown, no one can prove to him that he is wrong, unless he who denies their existence be a man of great ability and knowledge, and is willing to follow a long and laborious demonstration; he will remain unconvinced, and still insist that they cannot be known.

What do you mean, Parmenides? said Socrates.

PLATO — THE FORMS

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In the first place, I think, Socrates, that you, or anyone who maintains the existence of absolute essences, will admit that they cannot exist in us.

No, said Socrates; for then they would be no longer absolute.True, he said; and therefore when ideas are what they are in relation to one another, their essence is determined by a relation among themselves, and has nothing to do with the resemblances, or whatever they are to be termed, which are in our sphere, and from which we receive this or that name when we partake of them. And the things which are within our sphere [plane of existence] and have the same names with them, are likewise only relative to one another, and not to the ideas which have the same names with them, but belong to themselves and not to them. [skipping a bit now…]

PLATO — THE FORMS

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From Parmenides (Book about Parmenides by Plato, not Parmenides’ book) And the absolute natures or kinds are known severally by the absolute idea of knowledge?

Yes. And we have not got the idea of knowledge? No. Then none of the ideas are known to us, because we have no

share in absolute knowledge? I suppose not. Then the nature of the beautiful in itself, and of the good

in itself, and all other ideas which we suppose to exist absolutely, are unknown to us?

PLATO — THE FORMS

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From Meno Without any one teaching him he will recover his knowledge for himself, if he is only asked questions? ... And this spontaneous recovery of knowledge in him is recollection? ... And this knowledge which he now has must he not either have acquired or always possessed?

PLATO — THE FORMS

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In The Meno, Socrates interrogates a slave boy about geometry and finds that he knows the correct answers, despite never having been taught.

From MenoBut if he always possessed this knowledge he would always have known; or if he has acquired the knowledge he could not have acquired it in this life, unless he has been taught geometry; for he may be made to do the same with all geometry and every other branch of knowledge. Now, has any one ever taught him all this? ...

Meno: I am certain that no one ever did teach him. But if he did not acquire the knowledge in this life, then he must have

had and learned it at some other time? Which must have been the time when he was not a man? And if there have been always true thoughts in him, both at the time when he was and was not a man, which only need to be awakened into knowledge by putting questions to him, his soul must have always possessed this knowledge, for he always either was or was not a man? And if the truth of all things always existed in the soul, then the soul is immortal. Wherefore be of good cheer.

PLATO — THE FORMS

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PLATO — SUMMARY

• Summary:

• The Cave: people in the cave are seeing illusions, the lower part of the Line. If they break their chains (ignorance), they can then see the puppeteers, the fire. When they see this, they’re seeing the physical world and the causes of illusions. But to truly become enlightened, they have to start the journey up the slope out the cave, which is to become acquainted with principles, theories, science, etc. Once out the cave, they then see the Sun, the One Form, the Form of the Good. The Truth.

PLATO — SUMMARY

Veldkamp, Gabriele. Zukunftsorientierte Gestaltung informationstechnologischer Netzwerke im Hinblick auf die Handlungsfähigkeit des Menschen. Aachener Reihe Mensch und Technik, Band 15, Verlag der Augustinus Buchhandlung, Aachen 1996, Germany

The Cave

Source: Wikimedia Commons

PLATO — SUMMARY• Summary:

• The Line. Our episteme is divided up into four areas: illusions or mere beliefs and matters of the senses (the physical world), followed by the world of understanding (hypotheses), and Truth or Forms (reason). The first two levels are a posteriori, levels of lower understanding. The latter two levels are a priori, matters of higher understanding.

PLATO — SUMMARY• Summary:

• The Forms: Everything has a “type” or Form, which is a metaphysically separate entity corresponding to the type or Idea of the thing we are looking at. The Forms reside in the Realm of the Forms, and they exist separately to their objects (tokens).

• We experience reincarnation: that is, prior to our birth, our souls exist in the Realm of the Forms and become acquainted with them. When we are born into the physical world, we then recognise (recollect) the Forms that we saw, and recognise them again in the physical objects.

Criticism: The Forms • Recursion: If each object has a Form, then each triangle partakes in a

unique Form of a triangle; but then how are those Forms of triangles similar? They must partake in an uber-triangle Form, etc.

• The doctrine of the Forms is extravagant; it violates Occam’s Razor• Plato could dispense with commitments to immortality, a realm of the

Forms, reincarnation, explaining the mysterious “participation” or “partaking” relationship between tokens and types, not to mention the doctrine of recollection, if he were to understand how we learn, how we acquire knowledge, and how we come to generalise from tokens to types, rather than the other way around (the doctrine of the Forms is claiming that we know the token because we know the type).

PLATO — THE FORMS

Criticism: The Forms

• Furthermore, he is failing to distinguish between calculation (what the slave boy in Meno is doing, which doesn’t require knowledge at all, just logic), and knowledge (facts, data). Had he asked the boy for some fact (e.g. from history), the boy would have failed. Therefore, the doctrine of recollection is false.

• Furthermore, modern neuroscience can identify not only that it is brain activity which recognises forms of things, but which areas in particular in the brain.

• Refer back to Plato’s Parmenides, where Parmenides attacks the Forms.

PLATO — THE FORMS

Introduction • Plato’s main book on epistemology• Please see the course handout or the text of the Theaetetus

itself; we will not inspect it in detail in class.• The dialogue up to [170] seems to have two primary

compatible claims from Theaetetus and Protagoras:• Theaetetus claims that knowledge is perception (e.g. sight)• Protagoras claims that “What seems to a man, is to him

[true]”. IE epistemic relativism.• Most of the book represents various attempts to ascertain

what knowledge is, and reject relativism.

PLATO — THEAETETUS

a. Knowledge as Technai (skills)

• Theaetetus (in the narrative) gives a rundown of types of learning, in particular geometry, astronomy, music, and maths, and the specialties or aptitudes (technai) of cobbling. These he calls "knowledges,"

• Socrates objects:

• (a) what is common to all the different samples of knowledge, not a variety of various types of knowledge?


a. Knowledge as Technai (skills)

• Socrates objects:

• (b) Regardless of say, cobbling is “knowledge of how to make shoes,” one can't comprehend what cobbling is, unless one comprehends what knowledge is. However, in [170] and [178c] onwards, Socrates does argue precisely that Protagoras (the relativist) is wrong, because people have do expert knowledge or technai.


b. Knowledge as Perception

• Socrates shows how Theaetetus’ view is equivalent to Protagoras' saying, "Man is the measure of all things, of the things that will be that [or how] they are, of the things that are not that [or how] they are not." Socrates disputes this by showing the translation of Protagoras' principle as signifying “how things seem to an individual is the manner by which they are for that individual” (the cold wind example…).



• Socrates shows how Theaetetus’ view is equivalent to Protagoras' saying, "Man is the measure of all things, of the things that will be that [or how] they are, of the things that are not that [or how] they are not."

• How?

• Well, if knowledge is perception, we perceive things differently (wind example, wine example), with the result that knowledge depends on the perceiver. Thence, relativism.


b. Knowledge as Perception (contd)

• Socrates argues that since each man perceives things differently from his own perceptual point of view (e.g. when blindfolded, or subject to cold wind, or is now having wine whilst sick and then whilst not sick), it follows that the knowledge (perceptions) change from man to man and even from moment to moment within one man.

• This, then, shows that Theaetetus’ view, that perception is knowledge, dissolves into Protagoras’ view of individual relativism.



• Socrates then turns to the Heraclitean proposal of everything being in flux. The notion of Universal Flux makes every perception phenomenologically private. Again, thence relativism.

• However, there is a consequence that goes along with this. If everything is in flux — let’s say, radical flux, as Heraclitus might believe — then it follows that even ourselves can’t tell what it is that we believe or know.



• These private phenomena, it is argued, are unique from the point of view of the perceiver, and hence nobody can ever deny anyone else’s perceptions of truth since they are unique.

• Thence, … Relativism. Again.



The next objection to Protagoras/Relativism then goes as follows:

“(1) Numerous individuals accept that there are false convictions; in this way,

(2) If all convictions are valid, there are [per (1)] false convictions;

(3) If not all convictions are valid, there are false convictions;

(4) Consequently, in any case, there are false convictions.”


http://www.iep.utm.edu/theatetu/


Formally, this argument is something like the following (feel free to spot errors):

1. ∃S1, S2, S3: S1, S2, S3 ∈ ∃{Sn}

2. Q: ∃Sn: Sn(¬P)

3. P ⊃ Q

4. ∀(P): P; & Sn(Q)

5. Q ⊃ ¬P

6. ∴ ¬[∀(P): P]

7. Q & ¬P


There exist persons S1, S2, S3 in a set Sn

Prop. Q says that Sn holds that some prop. P is false

If P (is relativism), then all statements, even Q are true

For all P, where P might be relativism, P is true. (Protagoras’ claim) & Sn holds that Q, which is also true from 3

But If Q is true, P is false

Therefore it is not the case that for all P, P is true

Therefore Q and not P


• This conflicts with Protagoras’ truth claim, viz., that truth is relative to an individual and cannot be denied (see the argument from Flux above).

• Protagoras must accept, regarding his own claims, that the feeling of the individuals who think he isn't right is valid, since whatever someone feels is true for them (“Protagoras is wrong”) is true for them (knowledge). Thus even Protagoras must disagree with his own theory.



• Socrates then raises the objection about professional credibility, and why Protagoras should be more credible (why…) if truths spoken are relative only to the speaker, discussed above. In short, who is he to ask for money if everyone speaks the truth? For, since if Protagoras is consistent in his view, then he does not deserve to be paid, or, Socrates deserves to be paid, since Socrates’ opinions, by Protagoras’ epistemic relativism, are just as good as Protagoras’.

• In other words, if [what is true for Protagoras is true for Protagoras], and if [what is true for Socrates is true for Socrates], then Socrates is under no obligation to accept Protagoras’ view, that, [What is true for Protagoras is true for Protagoras: namely, epistemic relativism].



1. ∃P: S(P) & (S(P) ⊃ P) There exists P such that Socrates (S) holds that P and if S holds that P, then P is true

2. ∃R: p(R) & (p(R) ⊃ R) There exists R such that Protagoras (p) holds that R and if p holds that R, then R is true

3. P = ¬R P is the denial of R (relativism) because S disagrees with p

4. R = [P & R] Relativism means all things are true (both S and p are right)

5. R = [¬R & R] R is the same as [not-R and R], substituting in (3) (contradiction, circular/self- referential)

6. ¬R Because True AND False is False, [¬R & R] is necessarily false

7. Therefore ¬2 p is incorrect in his view that R



• In his third contention Socrates objects that professionals, such as medical doctors, do have skills and expertise which are superior and therefore can be relied on more than one’s own judgements. This means that we as individuals are not the best judges of truth (e.g. about whether we are sick and how long the sickness will last) [170, 178c et seq].

• However this seems to be confusing having knowledge-how vs having knowledge-that. One can grant that one can have a skill (“how”) without knowing “that” one has the skill, or how to explain it to others. (Compare to fallacious argument in the Meno).



• Fourth, Socrates argues that Protagoras must be able to see the future, since, if whatever he believes is true for him, even in the case of beliefs about the future, then no matter what happens, he would have known it was going to happen [178c].

• This means that Protagoras is omniscient, and even if a doctor says he will get sick, say, and Protagoras disagrees, then of necessity, Protagoras cannot get sick as long as he believes that he can’t.


c. Knowledge is True/Justified Belief

In the remainder of the Theaetetus (187b), Plato goes on to argue for knowledge as true belief with an account (logos)” or justification. (cf. 201c-d). Note that this is not the same as Heraclitus’ logos. Remember, ‘logos’ has many meanings.

[187b] “Theaetetus: To say that all opinion is knowledge is impossible, Socrates, for there is also false opinion; but true opinion [belief] probably is knowledge.”



• He then goes on to discuss how a belief could be false. This is important because it is the first time our modern account of knowledge as justified true belief is identified.



“[201a] Socrates: Well, then, this at least calls for slight investigation; for you have a whole profession which declares that true opinion is not knowledge.

Theaetetus: How so? What profession is it?

Socrates: …lawyers… [who] satisfactorily to teach the judges the truth about what happened to people who have been robbed of their money or have suffered other acts of violence, when there were no eyewitnesses?



Theaetetus: I certainly do not think so; but I think they can persuade them.Socrates: And persuading them is making them have an opinion, is it not.Theaetetus: Of course.Socrates: Then when judges are justly persuaded about matters which one can know only by having seen them and in no other way, in such a case, judging of them from hearsay, having acquired a true opinion of them, [201c] they have judged without knowledge, though they are rightly persuaded, if the judgement they have passed is correct, have they not?Theaetetus: Certainly.



Socrates: But, my friend, if true opinion and knowledge were the same thing in law courts, the best of judges could never have true opinion without knowledge; in fact, however, it appears that the two are different.”

• The trouble is, as he argues above, accidental beliefs, even if correct, cannot be called knowledge, hence, false knowledge [false belief or pseudo-knowledge] is impossible. This is interesting because it presages the famous 20th-century Gettier problems in epistemology.



“Theaetetus: Oh yes, I remember now, Socrates, having heard someone make the distinction, but I had forgotten it. He said that knowledge was true [true] opinion [belief] accompanied by reason [justification], [201d] but that unreasoning true opinion was outside of the sphere of knowledge [*why?]; and matters of which there is not a rational explanation are unknowable—yes, that is what he called them—and those of which there is are knowable.” [Pity we never find out who this “he” is].



• And here we see the first recorded claim that knowledge is justified (reasoned) true belief (opinion). After this, Socrates tries to explain what counts as something being justified or having a reason (‘logos’) or ‘account’.

• The dialogue does not officially come to a conclusion about what knowledge is. We know that Socrates holds truth to be “the Form of the Good”, but he doesn’t address that in this dialogue. Instead, he acts as a “midwife”, helping Theaetetus to see that he does not know what knowledge is.


• Thank you!

PLATO

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