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Topic #D33

Plato, Theaetetus 142a-162a


23 November 2001
Scribes: Rebecca Cuneo and Maddy Macdonald


These minutes were spoken on 26 November; for another version, go to the unspoken minutes



The Theaetetus is an incredible masterpiece of philosophy.  It is our earliest complete study of epistemology.  Protagoras’ Truth may be an earlier account of epistemology, but all that has come down to us from it is the opening words.   Epistemology is the study of knowledge and asks the question: “What is knowledge?”  Professor Hutchinson described the dialogue found in Theaetetus as unfathomably rich, and noted that he had spent an entire term studying it alone with students in a third year class.


On the outside, Thaeatetus is a return to a the Socratic form of dialogue, but at its core is a Platonic viewpoint.  As in his Symposium, Plato takes great pains at the beginning to establish the pedigree and hence the authority of the text.  The dialogue is also a tribute to Euclides, who was a good friend to both Plato and Socrates.  He had followers of whom we know little, apart from the fact that they did not shy away from abstract philosophical analysis.  The theme of the discussion asks: “What is knowledge?”  This is best inquired of talented people who possess abstract analytical skills, like geometers.  Plato approaches the topic in a teacherly way. 


Theodorus praises Theaetetus in a way which reflects Plato’s vision of the ideal student:

But as a matter of fact – if you’ll excuse my saying such a thing – he is not beautiful at all, but is rather like you, snub-nosed, with eyes that stick out; though these features are not quite so pronounced in him.  I speak without any qualms; and I assure you that among all the people I have ever met – and I have got to know a good many in my time- I have never yet seen anyone so amazingly gifted.  Along with a quickness beyond the capacity of most people, he has an unusually gentle temper; and, to crown it all, he is as manly as a boy as any of his fellows.  I never thought such a combination could exist; I don’t see it arising elsewhere.  People as acute and keen and retentive as he is are apt to be very unbalanced.  They get swept along with a rush, like ships without ballast; what stands for courage in their makeup is a kind of mad excitement; while on the other hand, the steadier sort of people are apt to come to their studies with minds that are sluggish, somehow – freighted with a bad memory.  But this boy approaches his studies in a smooth, sure effective way, and with great good temper; it reminds one of the quiet flow of a stream of oil.  The result is that it is astonishing to see how he gets through his work, at his age. (Theaetetus 143e-144b)


There are similar passages in Republic and Statesman regarding the temperamental qualities – a quick and active mind, and just the right amount of spirit, to name a few - that Plato thought made for a good student.  If there is a teacher, there must be a learner, and someone must be learning something new.  If the student is not learning, then the teacher is not teaching.  But, if there is no knowledge, then there can be neither teacher nor learner.  Plato thus wonders what truth a teacher might be trying to convey.


In Theaetetus, Socrates is not prepared to bring new ideas into the world, but he can help others accomplish this.  However, the viability rate of these new ideas is low.  Socrates likens himself to a mid-wife in this respect.  There was an ancient Greek ritual in which, to accept a newborn into the family, the father must pick up the child and walk around the hearth with it in his arms.  This was the signal the father had acknowledged paternity.  In ancient cultures, people would have to decide whether or not to abandon a sick child beyond the edge of the city.  Socrates, as mid-wife, examines newly born ideas and usually winds up discarding them.  One could say that he practises intellectual eugenics.


In philosophy, as in other skilled practices, the teacher must lead from behind.  The student performs his task, and the teacher then reinforces his correct acts, and discourages his incorrect tendencies.  All learning is a ultimately kind of self-teaching and self-realization.  This idea is reflected in a jocular context in Plato’s Symposium:

[Agathon] immediately called: “Socrates, come lie down next to me.  Who knows, if I touch you, I may catch a bit of the wisdom that came to you under my neighbour’s porch.  It’s clear you’ve seen the light.  If you hadn’t, you’d still be standing there.”

Socrates sat down next to him and said, “How wonderful it would be, dear Agathon, if the foolish were filled with wisdom simply by touching the wise.  If only wisdom were like water, which always flows from a full cup into an empty one when we connect them with a piece of yarn – well, then I would consider it the greatest prize to have the chance to lie down next to you.  I would soon be overflowing with your wonderful wisdom.” (Symposium 175d-e)


Plato, however, opposes this notion of knowledge.  He thinks knowing must be understood as a real relation between the object of knowledge and the knower.  In Theaetetus, however, we are treated to the pre-Socratic ‘materialist, swirling, relativist’ theory.  If knowledge is based on perception, then everyone’s perceptions are true.  As a teacher, Plato believes expertise equals learning the task, which equals knowledge.  Therefore, you can’t be a teacher if knowledge is relative. And, as a teacher, you cannot support a theory which denies the truth.  So the Sophists are ‘teachers’ whose doctrines apparently leave them nothing to teach. 


In his investigation of knowledge, Plato examines the pre-Socratic philosophical approach as exemplified by Protagoras, and looks into the nature of real learning and teaching.  At this point. suddenly, as an apparent digression, Socrates says:

That remark of yours, my friend, reminds me of an idea that has often occurred to me before – how natural it is that men who have spent a great part of their lives in philosophical studies make such fools of themselves when they appear as speakers in the law courts. (Theaetetus 172c)


Socrates and his brethren have no experience of law courts, and he (along with Plato) often criticizes those who scramble for political position.  They also criticize Isocrates’ school, a degree-granting institution which aimed at making students wiser and better counsel.  It offered a practical education for the public life. 


Plato admits that the philosopher can and perhaps should cut a ridiculous figure:

To begin with, then, the philosopher grows up without knowing the way to the market-place, or the whereabouts of the law courts or the council chambers or any other place of public assembly.  Laws and decrees, published orally or in writing, are things he never sees or hears.  The scrambling of political cliques for office; social functions, dinners, parties with flute-girls – such doings never enter his head even in a dream.  So, with questions of birth – he has no more idea whether a fellow citizen is high-born or humble, or whether he has inherited some taint from his forebears, male or female, than he has of the number of pints in the sea, as they say.  And in all these matters, he knows no even that he knows not; for he does not hold himself aloof from them in order to get a reputation, but because it is in reality only his body that lives and sleeps in the city.  His mind, having come to the conclusion that all these things are of little or no account, spurns them and purses its winged way, as Pindar says, throughout the universe, ‘in the deeps below the earth’ and ‘in the heights above the heaven’; geometrizing upon the earth, measuring its surfaces, astronomizing in the heavens; tracking down by every path the entire nature of each whole among the things that are, and never condescending to what lies near at hand.

THEODORUS:  What do you mean by that, Socrates?

SOCRATES:  Well, here’s an instance: they say Thales was studying the stars, Theodorus, and gazing aloft, when he fell into a well; and a witty and amusing Thracian servant-girl made fun of him because, she said, he was wild to know about what was up in the sky but failed to see what was in front of him and under his feet.  (Theaetetus 173d-174b)


The philosopher is so absorbed in his thoughts that he falls into wells. This stereotype does not necessarily apply to all philosophers and branches of philosophy.  Plato’s Socrates considers geometry to be a branch of philosophy, as the opening words of the inner dialogue attest:

If Cyrene were first in my affections, Theodorus, I should be asking you how things are there, and whether any of your young people are taking up geometry or any other branch of philosophy.  (Theaetetus 143d)


 Aristippus of Cyrene, on the other hand did not. 


Nevertheless, Socrates maintains:

It really is true that the philosopher fails to see his next-door neighbour, he not only doesn’t notice what he is doing; he scarcely knows whether he is a man or some other kind of creature.  The question he asks is, What is Man?  What actions and passions properly belong to human nature and distinguish it from all other beings?  This is what he wants to know and concerns himself to investigate.  (Theaetetus 174b)


At this point, Professor Hutchinson protested that this does not apply to all philosophers, because while he is a philosopher, he does know his neighbours’ names.  True, he was so absorbed in his re-reading of Theaetetus Friday morning that he was a little late for class.  Furthermore, he often neglects his personal grooming in favour of philosophical meditations – as his wife will attest.  Still, Epicurus was certainly a great thinker who spent his time teaching a very practical and worthwhile kind of philosophy to real individuals, whose names he certainly knew, not airy-fairy abstract speculation.  So Plato’s portrait of the philosopher is contestable; many great thinkers do not fit it.


Socrates attacks the theory that knowledge is perception by bringing up dreams.  The problem dreams present is as follows: although they are perceptions, dreams are not knowledge.  However, this attack is not conclusive: Socrates then rallies to Protagoras’ side and gives a stronger version of his arguments:

‘And I must beg you, this time, not to confine your attack to the letter of my doctrine.  I am now going to make its meaning clearer to you.  For instance, I would remind you of what we were saying before, namely, that to the sick man the things he eats both appear and are bitter, while to the healthy man they both appear and are the opposite.  Now what we have to do is not to make one of these two wiser than the other – that is not even a possibility – nor is it our business to make accusations, calling the sick man ignorant for judging as he does, and the healthy man wise, because he judges differently.  What we have to do is make a change from the one to the other, because the other state is better.  In education, too, what we have to do is to change a worse state into a better state; only whereas the doctor brings about the change by the use of drugs, the professional teacher does it by the use of words.  (Theaetetus 166e-167a)


His theory may have more strength than first appears.  On this view, expertise consists of knowing which beliefs are fruitful and which are fruitless.  In fact, it is quite consistent to think that what is true is also what is best to believe.  This is a pre-cursor to the modern philosophy of American pragmatism.