Plato's Theaetetus

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Table of Contents

Introduction        

First Definition: “Knowledge is perception”        

Second Definition: “Knowledge is True Judgement”        

Third Definition: Knowledge is True judgement with an account        

Conclusion        

Reference        

Introduction

Plato(c.427 – 347 BCE) is an Athenian philosopher- dramatist, who has had a great influence on Western intellectual tradition, is always compared with Confucius who also has had a great influence on Eastern intellectual tradition.  Plato is influenced by the trail, condemnation, and the execution of his teacher Socrates who claims to be a midwife to help young people generate ideas. Like other dialogues written by Plato, Theaetetus also has Socrates as its main character. And his two respondents are Theaetetus, a young brilliant man and Theaetetus’s mentor Theodorus who is a friend of Socrates. In Theaetetus, mostly conversions are between Socrates and Theaetetus because Theodorus thinks himself is less young and rather less smart than Theaetetus. Plato talks about knowledge in many books but not like other dialogues written by Plato, only Theaetetus offers a set-piece discussion about the nature of knowledge. There are three definitions of knowledge in Theaetetus but each of them is rejected by the end. The first definition is “Knowledge is perception” (Theaetetus 151e-187a). The second definition is “Knowledge is true judgement” (Theaetetus 187b-201c). The third definition is that “Knowledge is true judgement with an account” (Theaetetus 201d-210a).

First Definition: “Knowledge is perception”

1. At 151e Theaetetus claims: “Knowledge is nothing but perception”. It seems to him that “a person who knows something is to perceive the things he knows”.
2. Socrates then quote Protagoras’s thesis, that “a man is the measure of all things”, to point out that the definition is not an ordinary theory. “Man is the measure of all things” means that things are to any man just as they appear to that man. Socrates begins his present of Protagoras’s thesis by the argument that” the wind is cold to the one who feels cold, but not cold to the one who does not feel cold. So according to Protagoras’ view, both argument that “wind is cold” and “wind is not cold” are true. However, the wind itself is cold and not cold, is contradiction.  Amazingly, this seems plausible to Theaetetus. Socrates then adds Heracleitus’ view that “Everything is the offering of flux and change” which means everything is inactivity and always keep changing. And everything is in flux.
3. Socrates states the first objection of the flux theory at Theaetetus 157c-160c. This “asks how the flux theorist is to distinguish false(deceptive) appearances such as dreams from the true (undeceptive) appearance of the waking world” Chappell 2004 (79). According to flux theory, there should not be any “true” and “false” appearances to the same person. Or they should be described as different appearances to different people. At 160d, Socrates summaries all the things from 151-160.
4. Socrates then raised up several objections to Protagoras’ view. The first objection, is that if all perceptions are true, then there is no difference between animal perceptions and human perceptions. Socrates finds this situation is quite absurd. Because many animal perceptions are better than human perceptions like eagle’s eyesight. There is no need to prefer human perceptions when animals and humans are just as perceivers. The second objection makes the point that Protagoras’ opinion implies that no one has more wisdom than others. The argument against the idea that judgement that formed on the basis of perception by human is infallible. A third objection is quite similar to the first one. It regards humans and gods as perceivers, there is no need to prefer gods’ perceptions. This idea is also thought to be absurd by Socrates. Human’s perceptions are not inferior to the god’s perceptions. The only difference between humans and gods are their judgement about perceptions. Later at 163a-168c, Socrates present another four arguments. The forth one is that, if perception equals to knowledge, then when people hear the foreign language, they could know it immediately. Or when they don’t know a letter, they could not insist they don’t see it. The fifth comes up a similar problem that if memory equals to perception, then remembering things is knowing them but not perceiving them. The sixth objection is quite similar to the forth one since it points that if perception equals to knowledge, then one eye open and the other one close would lead to the contradiction that both knowing and not knowing one thing. The seventh objection states that one can perceive clearly and unclearly of one same thing, this does not apply to the way of knowing something. Protagoras, however, responses to these objections by giving two main points. Firstly, he meets some of the objection by “distinguishing types and occasions of perceptions”. Secondly, he claims that there is no true or false judgement but beneficial or not. So he just replaces his pupil’s mind with beneficial judgement but not teach them what is true judgement. Nevertheless, if everything is true judgement, then the idea, that other one could have better beneficial judgement than his, is contradict to itself. The next objection is the famous peritropê. “The peritropê objection is this. Suppose I believe that “All beliefs are true”, but also admit that “There is a belief that ‘Not all beliefs are true’”. If all beliefs are true, the belief that “Not all beliefs are true” must be true too. But if that belief is true, then by disquotation, not all beliefs are true. So I refute myself by contradicting myself” Chappell 2006 (109). The ninth objection that Socrates presents Protagoras’ theory with dilemma. This objection is a conceptual divorce between the notions of justice and benefit, which restrict the application of Protagoras’ theory to the notion of justice.
5. Socrates then raises up the the idea about digression. (172c-177b) Socrates and Theaetetus discuss about country, philosopher and those people who have been knocking a lot in court since they are young.
6. After the digression, Socrates returns to the last objection to Protagoras’ theory. His last objection is that there is no certain way for Protagoras’ theory to be applied to judgement about the future. Protagoras suggests that “the past may now be no more than whatever I now remember it to have been”. No prediction is ever proved to be wrong just as same as no memory is claimed to be inaccurate.
7. Protagoras’ theory has been proved to be false. And Socrates moves on to Heracleitus’ theory. Socrates argues that if Heracleitus’ theory is true, then it has no help to prove that knowledge is perception nor knowledge is not perception. Besides, Heracleitus cannot state something’s own doctrine.
8. Socrates finish his refutation by bringing the final objection which directly against the statement that “Knowledge is perception”. The objection states that minds use sets concepts which do not operate through the senses. So there is a part of knowledge has nothing to do with perception. Hence, knowledge is not perception.

Second Definition: “Knowledge is True Judgement”

1. At 187b, Theaetetus claims that Knowledge is True Judgement while there are some false judgements so it cannot say “Knowledge is Judgement” in general.
2. In 187e-188c, Socrates ask Theaetetus several questions like “is it possible that someone he thinking that things he knows are not those things but other things he knows”? This is kind of puzzle of that false belief is the proposal that false belief occurs when someone identifies one thing as another.
3. After that, Socrates gives the second puzzle about false belief. The second proposal says that false judgement is believing “what is not” or “things that are not”.
4. Socrates then propose that “a thing as false judgement, which is a sort of other-judging; it occurs when someone makes an interchange in his thinking and affirms that one of the things which are is another of the things which are.”  This judgement could be understood easier with the addition concept of inadvertency.
5.   Socrates’ fourth puzzle about false belief is the wax tablet. The wax tablet provides people with more accurate account of the nature of thought, and its relationship with perception.
6. The fifth puzzle about false belief raised up by Socrates is aviary. It is attempted by deploying a distinction between knowledge that someone barely has and knowledge that he is actually using.
7. After all of these puzzles, Socrates finally gives an example which directly against the statement that “Knowledge is true judgement”. Socrates take an lawyer for instance, the lawyer can lead people to true belief with his superior skills but can not lead people to knowledge. In other words, knowledge and true belief are different things.

Third Definition: Knowledge is True judgement with an account

1. At 201d, Theaetetus tells Socrates one thing, that is heard from others, that “knowledge is True Judgement with an Account”.
2. Socrates then talks to Theaetetus about his dream. In his dream, he saw only two kinds of existents, complexes and simples. Complexes can be explained with accounts and formed with simple things where simple things cannot be divided anymore. In the dream, knowledge is only complex and there is no knowledge of simples.
3. In 202d-206c, Socrates critiques his theory by attacking the statement that complexes and elements are distinguishable in respect of knowledge. Socrates at the end makes a point, that based on our experience of learning letters and syllables shows that it is more important to know elements that complexes, which indicated the statement that the simples or elements are unknowable is false.
4. Finally, Socrates brings to Theaetetus three attempts to understand Logos. These three attempts shows that the statement that “Knowledge is True Judgement with an Account” is false. And Socrates end the conversation latter.

Conclusion        

        The Theaetetus gives us three definition of knowledge. The first one is “Knowledge is perception.” The second one is that “Knowledge is true judgement”. The third one is that “Knowledge is true judgement with an account”. These definitions are all been attacked by Socrates and finally are proved to be false.