Lecture 7, Theaetetus : Plato’s refutation of empiricism and relativism

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Lecture 7, Theaetetus : Plato’s refutation of empiricism and relativism as preraration for his metaphysics

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Plato’s dialogue Theaetetus deals with a lot of philosophical themes : Among them are Socrates’ midwifery, Protagoras’ Man-Measure Statement, the flux theory of Heracleitus, Parmenides’ immovable Being, the comparison of the mind to an aviary, various steps of knowledge, etc.

Maybe we can define Theaetetus dialogue as Plato’ endeaver to refute and overcome the empiricism and relativism in the name of the famous sophist Protagoras. From this standpoint, Theaetetus is regarded as Plato’s trial of and preperation for the foundation of metaphysics as an absolute knowledge. However Plato’s effort to build an absolute philosophy takes in the first place on the form of epistemology, an attempt to answer the question: What is the knowledge on the whole? The epistemological endeavour, however, results in nothing. Socrates’ effort to reach the nature of knowledge runs into difficulties, Aporie.

In my opinion the answer to what knowledge is, is to be found in the Republic as the idea theory. Therefore the Theaetetus may be thought of as the preparation for the Republic. So to speak the Plato’s Theaetetus is compared to the Critique of Pure Reason by Kant, in which the function of human cognition is analyzed and limited.

Proceeding from the lower to the higher by three stages, in which perception, opinion, reasoning are successively examined, we first get rid of the confusion of the idea of knowledge and specific kinds of knowledge. (Benjamin Jowett)

In his view Jowett refers to the dialectical element of Theaetetus : While lower step of knowledge is annihilated, higher step of knowledge appears viz as in Hegel’s Phenomelogy of Spirit. The truth of lower step is preserved in the higher step.

In the Theaetetus the initial form of knowledge is perception-knowledge.

Plato’s Socrates asks young Theaetetus the nature of knowledge. In reply to this Theaetetus says that knowledge is sensible perception. In this regard perception-knowledge can be associated to Berkeley’s empiricism : Esse est percipi.

Then Socrates associates instantly the knowledge issue with the relativism of Protagoras as follows:

“Well, you have delivered yourself of a very important doctrine about knowledge; it is indeed the opinion of Protagoras, who has another way of expressing it. Man, he says, is the measure of all things, of the existence of things that are, and of the non-existence of things that are not”. (151e~152a)

Protagoras’ Man-Measure Statement is therefore related to the existence and the non-existence of things : The perception-knowledge is declared as same as the Man-Measure Statement of Protagoras. Jowett wonders however if this connection is Plato’s own interpretation.

The relativism of Protagoras has something to do with the problem of existence and nonexistence and the flux theory of Heracleitus. Consequently the relativism or subjectivism comes to be connected with other philosophies, i.e. those of Heracleitus and Parmenides. However Heracleitus’ philosophy of universal flux is superior to that of Parmenides, philosophy of unchangeable being. According to Plato, the relativism as perception-knowledge rests on the flux theory of Heracleitus. The motionless being of Parmenides is opposed to the flux theory.

Previous commentators of Theaetetus had neglected Plato’s frequent references to Parmenides and his thought in Theaetetus. Plato’s Socrates fails to reveal the nature of knowledge in Theaetetus, because Socrates as Plato’s advocate cannot find the truth with the party of Protagoras, Heracleitus Empedocles i.e. with the story of relativism, empiricism and universal flux as theory of becoming and motion. Plato thinks of the tale of immovable being and that of forms but does not discuss it in detail. The connection of being and form will be achieved in Republic.

But out of motion and change and admixture all things are becoming relatively to one another, which "becoming" is by us incorrectly called being, but is really becoming, for nothing ever is, but all things are becoming. Summon all philosophers-Protagoras, Heracleitus,

Empedocles, and the rest of them, one after another, and with the exception of Parmenides they will agree with you in this. (152d)

According to Plato’s translation, Protagoras, Heracleitus and Empedocles go hand in hand. As the advocates of universal flux, they are all opposed to Parmenides as that of constant being. Even Homer is supposed to take part in the flux theory. This may be an oversimplification of historical relation. Plato supposes that majority of the intellectual favour the universal flux of Heracleitus.

When the latter(=Homer of Tragedy) sings of Ocean whence sprang the gods, and mother Tethys, does he not mean that all things are the offspring, of flux and motion? (152d)

Otherwise Plato stresses the motionless Being of Parmenides against all the common thoughts of that time. The emphasis of the motionless Being will be later in Republic even more important.

Then once more: Is it your(=Theaetetus) opinion that nothing is but what becomes? the good and the noble, as well; as all the other things which we were just now mentioning?

Sensible perception guarantees the certainty of being before my eyes. What is and what is not is decided by my judgment of perception.

Then my perception is true to me, being inseparable from my own being; and, as Protagoras says, to myself I am judge of what is and what is not to me.

Although Plato summons the flux theory of Heracleitus and other thinker in order to analyze the relativism of Protagoras, a successful refutation of the relativism takes places in another way : When the truth is someone’s perception, he is always right. Therefore nobody needs to be taught. There is no difference of knowledge. Nobody can be wiser than me, because I am the measure of the truth.

For if truth is only sensation, and no man can discern another's feelings better than he, or has any superior right to determine whether his opinion is true or false, but each, as we have several times repeated, is to himself the sole judge, and everything that he judges is true and right, why, my friend, should Protagoras be preferred to the place of wisdom and instruction, and deserve to be well paid, and we poor ignoramuses have to go to him, if each one is the measure of his own wisdom?

Socrates puts the weakness of Protagoras very succinctly : If my judgment is always right and I myself is the place of wisdom and instruction, I need not learn wisdom and knowledge from someone else.

Protagoras’ relativism has contradiction : As a teaching business, it advocates the argument that everyone is right, “man is the measure of all things”. Protagoras’ “man” might means client or customer who needs sophist’s counselling or service. Protagoras was alledgedly well paid for his teaching.

Sophists were believed to help people strengthen their opinions and arguments. However, Man-Measure Statement is contradictory in itself.

Another strong argument against the perception-knowledge is the problem of recollection. Plato forms this problem as follows :

We asked, you recollect, whether a man who has learned something and remembers it does not know it.

When it comes to the knowledge as perception, knowledge is present, because perception is always present. Rigorously to say, pervious perception is not perception any more. Previous perception belongs to the realm of reflection, memory or thought. Therefore, the knowledge is separated from perception.

And so the Protagorean tale was brought to naught, and yours(=Theaetetus’) also about the identity of knowledge and perception. [164e]

# knowledge as judgment

The perception here has the same meaning as impression. Knowledge as perception or impression was disproved by the argument of equality and transience of perception.

The next two stages of cognition is followed by the perception-knowledge ; knowledge as judgment and knowledge as judgment with account. I.E. the knowledge is as assertion and reasoning to be thought of. However the basic insight is similar to that of perception-knowledge. The subjective approach to the possibility of knowledge runs into difficulties(Aporie). Meanwhile several important facts about the epistemology is found : the problem of mistake and that of right or wrong of cognition,

The error of judgment-knowledge is solved through the concept-pair of “have and possesion” and further through the allegory of aviary, which again can be related to the recollection theory from Meno by Plato.

SOCRATES: Well, may not a man 'possess' and yet not 'have' knowledge in the sense of which I am speaking? As you may suppose a man to have caught wild birds—doves or any other birds—and to be keeping them in an aviary which he has constructed at home; we might say of him in one sense, that he always has them because he possesses them, might we not? (197c)

Here an aviary refers to the mind of each man and various birds refer to sorts of knowledge. To possess a knowledge means to acquire a knowledge, to have a knowledge means to use the knowledge. Through the aviary tale we can explain many things related to knowledge, e.g. learning, mistake and forget. In the words of Socrates, “and so we are rid of the difficulty of a man's not knowing what he knows”, which originated from Meno.

However the last problem of epistemology is not yet solved with the allegory of aviary. Because the fallibility of knowledge can not be blocked from the subjective standpoint: Knowledge should be the identity of being and thought as is the case by Parmenides.

Relativism, empiricism and universal flux cannot the give the vaildity of knowledge. We must wait for The Republic.