Either way, Protagoras loses. Socrates argues that if Heracleitus' doctrine of flux is true, then no assertion whatever can properly be made. Therefore a Heracleitus' theory of flux no more helps to prove that knowledge is perception than that knowledge is not perception, and b Heracleiteans cannot coherently say anything at all, not even to state their own doctrine. There are two variants of the argument. On the first of these variants, evident in c2-e10, Socrates distinguishes just two kinds of flux or process, namely qualitative alteration and spatial motion, and insists that the Heracleiteans are committed to saying that both are continual.
On the second variant, evident perhaps at a1, e4—5, Socrates distinguishes indefinitely many kinds of flux or process, not just qualitative alteration and motion through space, and insists that the Heracleiteans are committed to saying that every kind of flux is continual. Now the view that everything is always changing in every way might seem a rather foolish view to take about everyday objects. But, as a2-b8 shows, the present argument is not about everyday objects anyway. Plato does not apply his distinction between kinds of change to every sort of object whatever, including everyday objects.
He applies it specifically to the objects if that is the word of Heracleitean metaphysics. These items are supposed by the Heracleitean to be the reality underlying all talk of everyday objects. It is at the level of these Heracleitean perceivings and perceivers that Plato's argument against Heracleitus is pitched. And it is not obviously silly to suppose that Heracleitean perceivings and perceivers are constantly changing in every way. McDowell —2 finds the missing link in the impossibility of identifications.
We cannot says McDowell identify a moving sample of whiteness, or of seeing, any longer once it has changed into some other colour, or perception. But this only excludes re identifications: presumably I can identify the moving whiteness or the moving seeing until it changes, even if this only gives me an instant in which to identify it. This point renders McDowell's version, as it stands, an invalid argument. If it is on his account possible to identify the moving whiteness until it changes , then it is on his account possible to identify the moving whiteness.
But if that is possible, then his argument contradicts itself: for it goes on to deny this possibility. Some other accounts of the argument also commit this fallacy. McDowell's and Sayre's versions of the argument also face the following objection. If meanings are not in flux, and if we have access to those meanings, nothing stops us from identifying the whiteness at least until it flows away.
But if meanings are in flux too, we will have the result that the argument against Heracleitus actually produces at a5: anything at all will count equally well as identifying or not identifying the whiteness. Socrates completes his refutation of the thesis that knowledge is perception by bringing a twelfth and final objection, directed against D1 itself rather than its Protagorean or Heracleitean interpretations. This objection says that the mind makes use of a range of concepts which it could not have acquired, and which do not operate, through the senses: e.
Therefore knowledge is not perception. Unitarians and Revisionists will read this last argument against D1 in line with their general orientations. Unitarians will suggest that Socrates' range of concepts common to the senses is a list of Forms. They will point to the similarities between the image of the senses as soldiers in a wooden horse that Socrates offers at d1 ff.
Revisionists will retort that there are important differences between the Heracleitean self and the wooden-horse self, differences that show that Heracleiteanism is no longer in force in — They will insist that the view of perception in play in — is Plato's own non-Heracleitean view of perception. Indeed even the claim that we have many senses pollai , rather than several enioi , tines , does not sound quite right, either in English or in Greek.
Answering this question is the main aim in — Empiricists claim that sensation, which in itself has no cognitive content, is the source of all beliefs, which essentially have cognitive content—which are by their very nature candidates for truth or falsity. So unless we can explain how beliefs can be true or false, we cannot explain how there can be beliefs at all. Hence Plato's interest in the question of false belief.
What Plato wants to show in — is that there is no way for the empiricist to construct contentful belief from contentless sensory awareness alone. The corollary is, of course, that we need something else besides sensory awareness to explain belief. In modern terms, we need irreducible semantic properties. In Plato's terms, we need the Forms.
In pursuit of this strategy of argument in —, Plato rejects in turn five possible empiricist explanations of how there can be false belief. In the First Puzzle a-c he proposes a basic difficulty for any empiricist. Then he argues that no move available to the empiricist circumvents this basic difficulty, however much complexity it may introduce the other four Puzzles: db. The proposal that gives us the Fourth Puzzle is disproved by the counter-examples that make the Fifth Puzzle necessary.
As for the Second Puzzle, Plato deploys this to show how empiricism has the disabling drawback that it turns an outrageous sophistical argument into a valid disproof of the possibility of at least some sorts of false belief. Thus — continues the critique of perception-based accounts of knowledge that — began. Contrary to what some—for instance Cornford—have thought, it is no digression from the main path of the Theaetetus.
On the contrary, the discussion of false belief is the most obvious way forward. As Plato stresses throughout the dialogue, it is Theaetetus who is caught in this problem about false belief. It is not Socrates, nor Plato. There is clear evidence at Philebus 38c ff.
Is it only false judgements of identity that are at issue in —, or is it any false judgement? One interpretation of — says that it is only about false judgements of misidentification. Call this view misidentificationism. The main alternative interpretation of — says that it is about any and every false judgement. Call this view anti-misidentificationism. The present discussion assumes the truth of anti-misidentificationism; see Chappell for the arguments. I turn to the detail of the five proposals about how to explain false belief that occupy Stephanus pages to of the dialogue.
The first proposal about how to explain the possibility of false belief is the proposal that false belief occurs when someone misidentifies one thing as another. To believe or judge falsely is to judge, for some two objects O1 and O2 , that O1 is O2. How can such confusions even occur? Plato presents a dilemma that seems to show that they can't. The objects of the judgement, O1 and O2 , must either be known or unknown to the judger x.
Suppose one of the objects, say O1 , is unknown to x. In that case, O1 cannot figure in x 's thoughts at all, since x can only form judgements using objects that he knows. So if O1 is not an object known to x , x cannot make any judgement about O1. A fortiori, then, x can make no false judgement about O1 either. So apparently false belief is impossible if the judger does not know both O1 and O2 ; but also impossible if he does know both O1 and O2.
Being acquainted with X and Y means knowing X and Y ; and anyone who knows X and Y will not mistake them for each other. Why think this a genuine puzzle? There seem to be plenty of everyday cases where knowing some thing in no way prevents us from sometimes mistaking that thing for something else. One example in the dialogue itself is at b cp. It is perfectly possible for someone who knows Socrates to see Theaetetus in the distance, and wrongly think that Theaetetus is Socrates.
The First Puzzle does not even get off the ground, unless we can see why our knowledge of X and Y should guarantee us against mistakes about X and Y. Who is the puzzle of a-c supposed to be a puzzle for? Plato would not be much of a philosopher if he made this mistake. If as is suggested in e. Chappell , ad loc. The nature of this basic difficulty is not fully, or indeed at all, explained by the First Puzzle.
We have to read on and watch the development of the argument of — to see exactly what the problem is that gives the First Puzzle its bite. But there can be no beliefs about nothing; and there are false beliefs; so false belief isn't the same thing as believing what is not. Some think the Second Puzzle a mere sophistry.
But just as you cannot perceive a nonentity, so equally you cannot believe one either. Then we shall say that the things that are believed are propositions, not facts… so a false belief is not directed at a non-existent. This raises the question whether a consistent empiricist can admit the existence of propositions. At least one great modern empiricist, Quine —7, thinks not.
Plato agrees: he regards a commitment to the existence of propositions as evidence of Platonism, acceptance of the claim that abstract objects and plenty of them genuinely exist. So an explanation of false judgement that invoked entities called propositions would be unavailable to the sort of empiricist that Plato has in his sights.
As pointed out above, we can reasonably ask whether Plato made this distinction, or made it as we make it. If the structure of the Second Puzzle is really as Bostock suggests, then the Second Puzzle is just the old sophistry about believing what is not cp. Parmenides DK 29B8 , Euthydemus e ff. Moreover, on this interpretation of the Second Puzzle, Plato is committed, in his own person and with full generality, to accepting at least provisionally a very bad argument for the conclusion that there can be no false belief.
It would be nice if an interpretation of the Second Puzzle were available that saw it differently: e. One such interpretation is defended e. The only available answer, when the judgement is taken as an unstructured whole, appears to be: Nothing. Notice that it is the empiricist who will most naturally tend to rely on this analogy. It is the empiricist who finds it natural to assimilate judgement and knowledge to perception, so far as he can. So we may suggest that the Second Puzzle is a mere sophistry for any decent account of false judgement, but a good argument against the empiricist account of false judgement that Plato is attacking.
The moral of the Second Puzzle is that empiricism validates the old sophistry because it treats believing or judging as too closely analogous to seeing: e4—7. For empiricism judgement, and thought in general, consists in awareness of the ideas that are present to our minds, exactly as they are present to our minds. It cannot consist in awareness of those ideas as they are not ; because according to empiricism we are immediately and incorrigibly aware of our own ideas, it can only consist in awareness of those ideas as they are. Nor can judgement consist in awareness of ideas that are not present to our minds, for according to empiricism what is not present to our minds cannot be a part of our thoughts.
Still less can judgement consist in awareness of ideas that do not exist at all. The empiricism that Plato attacks not only repeats this logical slide; it makes it look almost reasonable. The point of the Second Puzzle is to draw out this scandalous consequence. Perhaps the best way to read this very unclear statement is as meaning that the distinctive addition in the third proposal is the notion of inadvertency. The point of Socrates' argument is that this addition does not help us to obtain an adequate account of false belief because thought dianoia has to be understood as an inner process, with objects that we are always fully and explicitly conscious of.
If we are fully and explicitly conscious of all the objects of our thoughts, and if the objects of our thoughts are as simple as empiricism takes them to be, there is simply no room for inadvertency. But without inadvertency, the third proposal simply collapses back into the first proposal, which has already been refuted. The empiricist conception of knowledge that Theaetetus unwittingly brings forth, and which Socrates is scrutinising, takes the objects of thought to be simple mental images which are either straightforwardly available to be thought about, or straightforwardly absent.
The First Puzzle showed that there is a general problem for the empiricist about explaining how such images can be confused with each other, or indeed semantically conjoined in any way at all. The Third Puzzle restricts itself at least up to d7 to someone who has the requisite mental images, and adds the suggestion that he manages to confuse them by a piece of inadvertency. Socrates' rejoinder is that nothing has been done to show how there can be inadvertent confusions of things that are as simple and unstructured, and as simply grasped or not grasped, as the empiricist takes mental images to be.
Just as speech is explicit outer dialogue, so thought is explicit inner dialogue. In the discussion of the Fourth and Fifth Puzzles, Socrates and Theaetetus together work out the detail of two empiricist attempts to explain just this. It then becomes clearer why Plato does not think that the empiricist can explain the difference between fully explicit and not-fully-explicit speech or thought. Plato thinks that, to explain this, we have to abandon altogether the empiricist conception of thought as the concatenation somehow of semantically inert simple mental images.
Instead, we have to understand thought as the syntactic concatenation of the genuine semantic entities, the Forms. Mistakes in thought will then be comprehensible as mistakes either about the logical interrelations of the Forms, or about the correct application of the Forms to the sensory phenomena. The Wax Tablet passage offers us a more explicit account of the nature of thought, and its relationship with perception. The objects of perception, as before, are a succession of constantly-changing immediate awarenesses. The objects of thought, it is now added, are those objects of perception to which we have chosen to give a measure of stability by imprinting them on the wax tablets in our minds.
The image of memory as writing in the mind had currency in Greek thought well before Plato's time: see e. Aeschylus, Eumenides This new spelling-out of the empiricist account of thought seems to offer new resources for explaining the possibility of false belief.
The new explanation can say that false belief occurs when there is a mismatch, not between two objects of thought , nor between two objects of perception , but between one object of each type. This proposal faces a simple and decisive objection. No one disputes that there are false beliefs that cannot be explained as mismatches of thought and perception: e. The Wax Tablet does not explain how such false beliefs happen; indeed it entails that they can't happen. Such mistakes are confusions of two objects of thought, and the Wax Tablet model does not dispute the earlier finding that there can be no such confusions.
So the Wax Tablet model fails. There is of course plenty more that Plato could have said in criticism of the Wax Tablet model. Most obviously, he could have pointed out the absurdity of identifying any number with any individual's thought of that number e9 ff. In the present passage Plato is content to refute the Wax Tablet by the simplest and shortest argument available: so he does not make this point.
But perhaps the point is meant to occur to the reader; for the same absurdity reappears in an even more glaring form in the Aviary passage. If we had a solution to the very basic problem about how the empiricist can get any content at all out of sensation, then the fourth proposal might show how the empiricist could explain false belief involving perception. The fifth and last proposal about how to explain the possibility of false belief attempts to remedy the fourth proposal's incapacity—which Plato says refutes it, c5—7—to deal with cases of false belief involving no perception, such as false arithmetical beliefs.
It attempts this by deploying a distinction between knowledge that someone merely has latent knowledge and knowledge that he is actually using active knowledge. The suggestion is that false belief occurs when someone wants to use some item of latent knowledge in his active thought, but makes a wrong selection from among the items that he knows latently. If this proposal worked it would cover false arithmetical belief.
But the proposal does not work, because it is regressive. If there is a problem about the very possibility of confusing two things, it is no answer to this problem to suppose that for each thing there is a corresponding item of knowledge, and that what happens when two things are confused is really that the two corresponding items of knowledge are confused a-b.
The Aviary rightly tries to explain false belief by complicating our picture of belief. But it complicates in the wrong way and the wrong place. It is no help to complicate the story by throwing in further objects of the same sort as the objects that created the difficulty about false belief in the first place. As with the conception of the objects of thought and knowledge that we found in the Wax Tablet, it is this lack of aspects that dooms the Aviary's conception of the objects of knowledge too.
At first only two answers seem possible: either he decides to activate 12, or he decides to activate If he decides to activate 12, then we cannot explain the fact that what he actually does is activate 11, except by saying that he mistakes the item of knowledge which is 11 for the item of knowledge which is But this mistake is the very mistake ruled out as impossible right at the beginning of the inquiry into false belief a-c.
Alternatively, if he decides to activate 11, then we have to ask why he decides to do this. At e1 ff. Theaetetus suggests an amendment to the Aviary. This is that we might have items of ignorance in our heads as well as items of knowledge. As Socrates remarks, these ignorance-birds can be confused with knowledge-birds in just the same way as knowledge-birds can be confused with each other.
So the addition does not help. At dc Socrates argues more directly against D2. He offers a counter-example to the thesis that knowledge is true belief. A skilled lawyer can bring jurymen into a state of true belief without bringing them into a state of knowledge; so knowledge and true belief are different states. This implies that there can be knowledge which is entirely reliant on perception.
One way out of this is to deny that Plato ever thought that knowledge is only of the Forms, as opposed to thinking that knowledge is paradigmatically of the Forms. For this more tolerant Platonist view about perception see e. Philebus 58dd, and Timaeus 27d ff. A third problem about the jury argument is that Plato seems to offer two incompatible explanations of why the jury don't know: first that they have only a limited time to hear the arguments b3, e1 ; and second that their judgement is second-hand b9. D3 apparently does nothing at all to solve the main problems that D2 faced.
Besides the jurymen counter-example just noted, showed that we could not define knowledge as true belief unless we had an account of false belief. This problem has not just evaporated in — It will remain as long as we propose to define knowledge as true belief plus anything. Significantly, this does not seem to bother Plato—as we might expect if Plato is not even trying to offer an acceptable definition of knowledge, but is rather undermining unacceptable definitions. One crucial question about Theaetetus — is the question whether the argument is concerned with objectual or propositional knowledge.
This is a basic and central division among interpretations of the whole passage —, but it is hard to discuss it properly without getting into the detail of the Dream Theory: see section 8a. A second question, which arises often elsewhere in the Theaetetus , is whether the argument's appearance of aporia reflects genuine uncertainty on Plato's part, or is rather a kind of literary device. Is Plato thinking aloud, trying to clarify his own view about the nature of knowledge, as Revisionists suspect?
Or is he using an aporetic argument only to smoke out his opponents, as Unitarians think? The evidence favours the latter reading. So it appears that, in the Theaetetus , Plato cannot be genuinely puzzled about what knowledge can be. Nor can he genuinely doubt his own former confidence in one version of D3.
If he does have a genuine doubt or puzzle of this sort, it is simply incredible that he should say what he does say in — without also expressing it. What Plato does in — is: present a picture Socrates' Dream of how things may be if D3 is true cc ; raise objections to the Dream theory which are said b12 to be decisive cc ; and present and reject three further suggestions about the meaning of logos , and so three more versions of D3 ca.
If what Plato wants to tell us in Theaetetus — is that he no longer accepts any version of D3, not even his own version, then it is extraordinary that he does not even mention his own version, concentrating instead on versions of D3 so different from Plato's version as to be obviously irrelevant to its refutation.
Unitarians can suggest that Plato's strategy is to refute what he takes to be false versions of D3 so as to increase the logical pressure on anyone who rejects Plato's version of D3. In particular, he wants to put pressure on the empiricist theories of knowledge that seem to be the main target of the Theaetetus. What Plato wants to show is, not only that no definition of knowledge except his own, D3, is acceptable, but also that no version of D3 except his own is acceptable. Rather as Socrates offered to develop D1 in all sorts of surprising directions, so now he offers to develop D3 into a sophisticated theory of knowledge.
Taken as a general account of knowledge, the Dream Theory implies that knowledge is only of complexes, and that there can be no knowledge of simples. Socrates attacks this implication. A common question about the Dream Theory is whether it is concerned with objectual or propositional knowledge. On this reading, the Dream Theory claims that simple, private objects of experience are the elements of the proposition; thus, the Dream Theory is both a theory about the structure of propositions and a theory about simple and complex objects.
If the Dream theorist is a Logical Atomist, he will think that there is a clear sense in which people, and everything else, are composed out of sense data. He will also think that descriptions of objects, too, are complexes constructed in another way out of the immediately available simples of sensation.
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For such a theorist, epistemology and semantics alike rest upon the foundation provided by the simple objects of acquaintance. Both thought and meaning consist in the construction of complex objects out of those simple objects. Philosophical analysis, meanwhile, consists in stating how the complexes involved in thought and meaning are constructed out of simples. This statement involves, amongst other things, dividing down to and enumerating the simple parts of such complexes.
What then is the relation of the Dream Theory to the problems posed for empiricism by the discussion of D2 in —? The fundamental problem for empiricism, as we saw, is the problem how to get from sensation to content : the problem of how we could start with bare sense-data, and build up out of them anything that deserved to be called meaning.
Plato thinks that there is a good answer to this, though it is not an empiricist answer. Sense experience becomes contentful when it is understood and arranged according to the structures that the Forms give it. The empiricist cannot offer this answer to the problem of how to get from sensation to content without ceasing to be an empiricist. What the empiricist can do is propose that content arises out of sets of sense experiences.
We get to the level of belief and knowledge only when we start to consider such sets: before that we are at the level only of perception. Our beliefs, couched in expressions that refer to and quantify over such sets, will then become knowledge a when they are true, and b when we understand the full story of their composition out of such sets. The Dream Theory says that knowledge of O is true belief about O plus an account of O 's composition. Socrates' main strategy in d8—c2 is to attack the Dream's claim that complexes and elements are distinguishable in respect of knowability. To this end he deploys a dilemma.
A complex, say a syllable, is either a no more than its elements its letters , or b something over and above those elements. If I am to know a syllable SO , and that syllable is no more than its elements, then I cannot know the syllable SO without also knowing its elements S and O.
Indeed, it seems that coming to know the parts S and O is both necessary and sufficient for coming to know the syllable SO. This result contradicts the Dream Theory. In that case, to know the syllable is to know something for which knowledge of the elements is not sufficient. But then the syllable does not have the elements as parts: if it did, that would compromise its singularity. And if the elements are not the parts of the syllable, nothing else can be.
So the syllable has no parts, which makes it as simple as an element. Thus if the element is unknowable, the syllable must be unknowable too. This result contradicts the Dream Theory too.
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Finally, in a1-c2, Plato makes a further, very simple, point against the Dream Theory. Our own experience of learning letters and syllables shows that it is both more basic and more important to know elements than complexes, not vice versa as the Dream Theory implies. The refutation of the Dream Theory's attempt to spell out what it might be like for D3 to be true is followed by three attempts to give an account of what a logos is.
Since such a person can enumerate the elements of the complex, i. Since he can arrange those letters in their correct order a9—10 , he also has true belief. Why not, we might ask? To see the answer we should bring in what Plato says about syllables at d8—a3. Those principles are principles about how letters form syllables, and how syllables form names.
It might even be able to store such a correct ordering in its electronic memory. What is missing is an awareness of bridging or structuring principles, rules explaining how we get from strings of symbols, via syllables, to representations of Greek names. So, presumably, knowledge of say Theaetetus consists in true belief about Theaetetus plus an account of what differentiates Theaetetus from every other human. Socrates offers two objections to this proposal. The Theaetetus is an extended attack on certain assumptions and intuitions about knowledge that the intelligent man-in-the-street—Theaetetus, for instance—might find initially attractive, and which some philosophers known to Plato—Protagoras and Heracleitus, for instance—had worked up into complex and sophisticated philosophical theories.
The first part of the Theaetetus attacks the idea that knowledge could be simply identified with perception. Perceptions alone have no semantic structure. So if this thesis was true, it would be impossible to state it. The second part attacks the suggestion that knowledge can be defined as true belief, where beliefs are supposed to be semantically-structured concatenations of sensory impressions. Against this Plato argues that, unless something can be said to explain how impressions can be concatenated so as to give them semantic structure, there is no reason to grant that the distinction between true and false applies to such beliefs any more than it does to perceptions.
Finally, in the third part of the Theaetetus , an attempt is made to meet this challenge, and present some explanation of how semantic structures can arise out of mere perceptions or impressions. On this conception, knowledge will come about when someone is capable not only of using such logical constructions in thought, but of understanding how they arise from perception. Socrates' basic objection to this theory is that it still gives no proper explanation of how this logical construction takes place. Without such an explanation, there is no good reason to treat the complexes that are thus logically constructed as anything other than simples in their own right.
We need to know how it can be that, merely by conjoining perceptions in the right way, we manage to achieve a degree of semantic structure that for instance makes it possible to refer to things in the world , such as Theaetetus. But this is not explained simply by listing all the simple perceptions that are so conjoined. Nor—and this is where we reach the third proposal of b11—a9—is it explained by fixing on any of those perceptions in particular, and taking it to be the special mark of Theaetetus whereby reference to Theaetetus is fixed.
The third proposal about how to understand logos faces the difficulty that, if it adds anything at all to differentiate knowledge of O from true belief about O , then what it adds is a diagnostic quality of O. If there is a problem about how to identify O , there is a problem about how to identify the diagnostic quality too. This launches a vicious regress. One way of preventing this regress is to argue that the regress is caused by the attempt to work up a definition of knowledge exclusively out of empiricist materials.
Hence there is no way of avoiding such a vicious regress if you are determined to try to define knowledge on an exclusively empiricist basis. The right response is to abandon that attempt. Knowledge is indeed indefinable in empiricist terms. In those terms, it has no logos. In those terms, therefore, knowledge itself is unknowable.
The official conclusion of the Theaetetus is that we still do not know how to define knowledge. Even on the most sceptical reading, this is not to say that we have not learned anything about what knowledge is like. As Theaetetus says b6 , he has given birth to far more than he had in him. And as many interpreters have seen, there may be much more to the ending than that.
It may even be that, in the last two pages of the Theaetetus , we have seen hints of Plato's own answer to the puzzle. Perhaps understanding has emerged from the last discussion, as wisdom did from d-e, as the key ingredient without which no true beliefs alone can even begin to look like they might count as knowledge. Perhaps it is only when we, the readers, understand this point—that epistemological success in the last resort depends on having epistemological virtue—that we begin not only to have true beliefs about what knowledge is, but to understand knowledge.
References to Plato's Theaetetus follow the pagination and lineation of E. Duke, W. Hicken, W. Nicholl, D. Robinson, J. Strachan, edd. Plato Plato: method and metaphysics in the Sophist and Statesman Plato: middle period metaphysics and epistemology Platonism: in metaphysics. Introduction 2. Summary of the Dialogue 3. Overall Interpretations of the Theaetetus 4. The Introduction to the Dialogue: ae 5.
Definition by Examples: ad 6. Introduction The Theaetetus, which probably dates from about BC, is arguably Plato's greatest work on epistemology. Summary of the Dialogue At the gates of the city of Megara in BC, Eucleides and Terpsion hear a slave read out Eucleides' memoir of a philosophical discussion that took place in BC, shortly before Socrates' trial and execution ac. Overall Interpretations of the Theaetetus The Theaetetus is a principal field of battle for one of the main disputes between Plato's interpreters.
The Introduction to the Dialogue: ae We should not miss the three philosophical theses that are explicitly advanced in the Introduction. To learn is to become wiser about the topic you are learning about d8—9. For instance, the outline shows how important it is for an overall understanding of the Theaetetus to have a view on the following questions of detail more about them later : At ac, is Socrates just reporting, or also endorsing, a Heracleitean flux theory of perception?
What is the date of the Timaeus , which seems 28—29, 45b—46c, 49e to present a very similar theory of perception to that found in Theaetetus —7? What does Plato take to be the logical relations between the three positions under discussion in — D1, Protagoras' theory, and Heracleitus' theory? The closer he takes them to be, the more support that seems to give to the Revisionist view that the whole of — is one gigantic modus tollens.
The more separate they are, the better for those versions of Unitarianism that suggest that Plato wants to pick and choose among the positions offered in — So much for the overall structure of —; now for the parts. After a passage e1—d5 in which Socrates presents what seem to be deliberately bad arguments, eight of them, for Heracleitus' flux thesis, Socrates notes three shocking theses which the flux theory implies: Qualities have no independent existence in time and space d6-e1. Qualities do not exist except in perceptions of them e3—a8. The dice paradox: changes in a thing's qualities are not so much changes in that thing as in perceptions of that thing a9—c6.
A distinction between bare sensory awareness, and judgement on the basis of such awareness. This is where the argument ends, and Socrates leaves to meet his accusers. Conclusion The Theaetetus is an extended attack on certain assumptions and intuitions about knowledge that the intelligent man-in-the-street—Theaetetus, for instance—might find initially attractive, and which some philosophers known to Plato—Protagoras and Heracleitus, for instance—had worked up into complex and sophisticated philosophical theories.
Bibliography References to Plato's Theaetetus follow the pagination and lineation of E. Allen, R. Ast, F. Berkeley, G. Bostock, D. Burnyeat, M. Campbell, L. Chappell, T. Cherniss, H. Cherniss, Selected Papers , Leiden: Brill, , pp. Cornford, F. Crombie, I. Denyer, N. Fine, Gail, , "False belief in the Theaetetus ", Phronesis , 70— Fine, Gail, , "Protagorean relativisms", in J.
Cleary and W. Wians eds. Geach, P. Knowledge and Self-Knowledge in Plato's Theaetetus advances a new explanation for the apparent failure of the Theaetetus to come to a satisfactory conclusion about the definition of knowledge. Tschemplik argues that understanding this aporetic dialogue in light of the fact that it was conducted with two noted mathematicians shows that for Plato, mathematics was not the paradigm for philosophy.
She points out that, although mathematics is clearly an important part of the philosopher's training, as the educational outline of the Republic makes clear, the point on which the mathematician falls short is the central role that self-knowledge plays in philosophical investigation. Theaetetus betrays this deficiency and is led by Socrates to an understanding of the benefits of self-knowledge understood as the knowledge of ignorance.
Tschemplik concludes that it is the absence of self-knowledge in the Theaetetus which leads to its closing impasse regarding knowledge.