Plato:Theaetetus

platoThe Theaetetus is one of the middle to later dialogues of the aboriginal Greek philosopher Plato. Plato was Socrates' student and Aristotle's teacher. Equally in most of Plato'southward dialogues, the master grapheme is Socrates. In the Theaetetus, Socrates converses with Theaetetus, a boy, and Theodorus, his mathematics teacher. Although this dialogue features Plato's most sustained discussion on the concept of noesis, it fails to yield an adequate definition of knowledge, thus ending inconclusively. Despite this lack of a positive definition, the Theaetetus has been the source of endless scholarly fascination. In improver to its main emphasis on the nature of cognition, it considers a broad diversity of philosophical issues: the Socratic Dialectic, Heraclitean Flux, Protagorean Relativism, rhetorical versus philosophical life, and false judgment. These issues are besides discussed in other Platonic dialogues.

The Theaetetus poses a special difficulty for Plato scholars trying to interpret the dialogue: in low-cal of Plato'south metaphysical and epistemological commitments, expounded in earlier dialogues such as the Democracy, the Forms are the just suitable objects of knowledge, and yet the Theaetetus fails explicitly to acknowledge them. Might this failure mean that Plato has lost faith in the Forms, as the Parmenides suggests, or is this omission of the Forms a calculated move on Plato's office to show that knowledge is indeed indefinable without a proper acknowledgement of the Forms? Scholars have also been puzzled by the moving picture of the philosopher painted by Socrates in the digression: at that place the philosopher emerges as a homo indifferent to the affairs of the city and concerned solely with "becoming as much godlike as possible." What does this version of the philosophic life have to do with a city-bound Socrates whose chief concern was to benefit his fellow citizens? These are only two of the questions that have preoccupied Plato scholars in their endeavour to interpret this highly complex dialogue.

Table of Contents

  1. The Characters of Plato'south Theaetetus
  2. Appointment of Composition
  3. Outline of the Dialogue
    1. Knowledge as Arts and Sciences (146c – 151d)
    2. Knowledge equally Perception (151d – 186e)
    3. Knowledge equally True Judgment (187a – 201c)
    4. Knowledge as Truthful Judgment with Logos (201c – 210d)
  4. References and Further Reading
    1. Full general Commentaries
    2. Knowledge as Arts and Sciences
    3. Knowledge as Perception
    4. Knowledge equally True Judgment
    5. Cognition as True Judgment with Logos

i. The Characters of Plato's Theaetetus

In the Theaetetus, Socrates converses with 2 mathematicians, Theaetetus and Theodorus. Theaetetus is portrayed as a physically ugly but extraordinarily astute male child, and Theodorus is his mathematics teacher. According to the Oxford Classical Dictionary, Theaetetus lived in Athens (c. 415–369 BCE) and was a renowned geometer. He is credited with the theory of irrational lines, a contribution of fundamental importance for Euclid'south Elements X. He besides worked out constructions of the regular solids similar those in Elements Xiii. Theodorus lived in Cyrene in the late fifth century BCE. In the dialogue, he is portrayed as a friend of Protagoras, well-aware of the Sophist's teachings, and quite unfamiliar with the intricacies of Socratic Dialectic. As far every bit his scientific work is concerned, the only existing source is Plato's Theaetetus: In the dialogue, Theodorus is portrayed every bit having shown the irrationality of the square roots of 3, five, half dozen, 7, … ,17.  Irrational numbers are numbers equal to an ordinary fraction, a fraction that has whole numbers in its numerator and denominator. The passage has been interpreted in many different means, and its historical accuracy has been disputed.

2. Date of Composition

The introduction of the dialogue informs the reader that Theaetetus is existence carried abode dying of wounds and dysentery after a battle near Corinth. There are two known battles that are peradventure the one referred to in the dialogue: the first one took place at about 394 BCE, and the other occurred at around 369 BCE. Scholars ordinarily prefer the battle of 369 BCE as the battle referred to in the dialogue. The dialogue is a tribute to Theaetetus' memory and was probably written before long after his death, which near scholars appointment effectually 369 – 367 BCE. It is uncontroversial that the Theaetetus, the Sophist and the Statesman were written in that order. The chief evidence for this order is that the Sophist begins with a reference dorsum to the Theaetetus and a reference frontward to the Statesman. In addition, there is a number of thematic continuities betwixt the Theaetetus and the Sophist (for instance, the concept of "faux belief," and the notions of "being," "sameness," and "difference") and between the Sophist and the Statesman (such as the use of the method of "drove and division").

3. Outline of the Dialogue

The dialogue examines the question, "What is knowledge (episteme)?" For heuristic purposes, it can be divided into four sections, in which a different reply to this question is examined: (i) Knowledge is the various arts and sciences; (2) Knowledge is perception; (3) Cognition is true judgment; and (four) Knowledge is true judgment with an "account" (Logos). The dialogue itself is prefaced by a conversation between Terpsion and Euclid, in the latter'due south house in Megara. From this conversation we larn about Theaetetus' wounds and impending expiry and well-nigh Socrates' prophecy regarding the future of the young human. In addition, we learn about the dialogue'due south recording method: Euclid had heard the entire conversation from Socrates, he so wrote down his memoirs of the chat, while checking the details with Socrates on subsequent visits to Athens. Euclid'southward role did not consist simply in writing downwards Socrates' memorized version of the actual dialogue; he also chose to cast it in direct dialogue, as opposed to narrative class, leaving out such connecting sentences as "and I said" and "he agreed." Finally, Euclid's product is read for him and for Terpsion past a slave. This is the only Platonic dialogue which is beingness read past a slave.

a. Knowledge as Arts and Sciences (146c – 151d)

To Socrates' question, "What is knowledge?," Theaetetus responds by giving a list of examples of knowledge, namely geometry, astronomy, harmonics, and arithmetics, as well as the crafts or skills (technai) of cobbling and and then on (146c–d). These he calls "knowledges," presumably thinking of them as the various branches of noesis. As Socrates correctly observes, Theaetetus' answer provides a list of instances of things of which at that place is knowledge. Socrates states iii complaints against this response: (a) what he is interested in is the 1 thing common to all the various examples of knowledge, not a multiplicity of different kinds of knowledge; (b) Theaetetus' response is circular, because fifty-fifty if one knows that, say, cobbling is "knowledge of how to make shoes," 1 cannot know what cobbling is, unless one knows what knowledge is; (c) The youth's answer is needlessly long-winded, a brusque formula is all that is required. The definition of clay as "world mixed with water," which is as well evoked by Aristotle in Topics 127a, is representative of the type of definition needed here. Theaetetus offers the following mathematical example to show that he understands Socrates' definitional requirements: the geometrical equivalents of what are now called "surds" could be grouped in 1 class and given a unmarried name ("powers") by dint of their common characteristic of irrationality or incommensurability. When he tries to use the same method to the question nearly knowledge, yet, Theaetetus does not know how to go along. In a justly celebrated image, Socrates, like an intellectual midwife, undertakes to assist him in giving birth to his ideas and in judging whether or not they are legitimate children. Socrates has the ability to make up one's mind who is mentally significant, by knowing how to apply "medicine" and "incantations" to induce mental labor. Socrates as well has the ability to tell in whose company a young human may benefit academically. This latter skill is not one that ordinary midwives seem to accept, simply Socrates insists that they are the most reliable matchmakers, and in order to testify his assertion he draws upon an agricultural analogy: just equally the farmer not but tends and harvests the fruits of the earth, but also knows which kind of earth is best for planting various kinds of seed, so the midwife's art should include a noesis of both "sowing" and "harvesting." Simply unlike common midwives, Socrates' art deals with the soul and enables him to distinguish and embrace truthful beliefs rather than faux beliefs. By combining the technê of the midwife with that of the farmer, Socrates provides in the Theaetetus the most celebrated illustration for his own philosophical practise.

b. Knowledge every bit Perception (151d – 186e)

Encouraged by Socrates' maieutic intervention, Theaetetus comes up with a serious proposal for a definition: cognition is perception. Satisfied with at least the grade of this definition, Socrates immediately converts information technology into Protagoras' homo-mensura doctrine, "Man is the measure out of all things, of the things that are that [or how] they are, of the things that are not that [or how] they are not." The Protagorean thesis underscores the declared fact that perception is not simply an infallible but also the sole grade of cognition, thereby bringing out the implicit assumptions of Theaetetus' full general definition. Socrates effects the complete identity between cognition and perception past bringing together two theses: (a) the interpretation of Protagoras' doctrine as pregnant "how things announced to an individual is how they are for that individual" (due east.g., "if the wind appears cold to 10, and so it is common cold for Ten"); and (b) the equivalence of "Y appears F to X" with "Ten perceives Y every bit F" (eastward.g., "the wind appears cold to Socrates" with "Socrates perceives the air current as common cold"). His next move is to build the ontological foundation of a earth that guarantees perceptual infallibility. For that, Socrates turns to the Heraclitean postulate of Radical Flux, which he attributes to Protagoras as his Secret Doctrine. Virtually all commentators acknowledge that Protagoras' hole-and-corner instruction is unlikely to be a historically authentic representation of either Protagoras' ontological commitments or Heraclitus' Flux doctrine. The notion of Universal Flux makes every visual event—for instance the visual perception of whiteness—the private and unique production of interaction between an private's eyes and an external move. Later this privacy is explained with the metaphor of the perceiver and the perceived object every bit parents birthing a twin offspring, the object's whiteness and the subject'south respective perception of it. Both parents and offspring are unique and unrepeatable: there can be no other, identical interaction between either the aforementioned parents or different parents able to produce the same offspring. No two perceptions can thus e'er be in conflict with each other, and no ane tin can ever refute anyone else'south perceptual judgments, since these are the products of instantaneous perceptual relations, obtaining between ever-changing perceiving subjects and ever-changing perceived objects. Although the assimilation of Protagorean Relativism to Theaetetus' definition requires the application of the doctrine to Perceptual Relativism—which explains Socrates' extensive focus on the mechanics of perception—one should bear in listen that the man-as-measure thesis is broader in telescopic, encompassing all judgments, especially judgments concerning values, such every bit "the just" and "the expert," and non just narrowly sensory impressions. Socrates launches a critique confronting both interpretations of Protagoreanism, beginning with its wide—moral and epistemological—dimensions, and last with its narrow, perceptual aspects.

Socrates attacks broad Protagoreanism from within the standpoint afforded him past 3 main arguments. Beginning, Socrates asks how, if people are each a measure of their ain truth, some, amid whom is Protagoras himself, tin be wiser than others. The aforementioned argument appears in Cratylus 385e–386d as a sufficient refutation of the human being-mensura doctrine. The Sophists' imagined answer evinces a new conceptualization of wisdom: the wisdom of a instructor like Protagoras has nothing to do with truth, instead information technology lies in the fact that he can better the way things announced to other people, just as the skilful doctor makes the patient feel well past making his food taste sweet rather than bitter, the farmer restores wellness to sickly plants past making them experience better, and the educator "changes a worse country into a better land" past means of words (167a).

The second critique of Protagoras is the famous self-refutation argument. It is essentially a 2-pronged statement: the first part revolves around false behavior, while the second function, which builds on the findings of the first, threatens the validity of the human being-as-measure doctrine. The erstwhile can be sketched as follows: (one) many people believe that there are false beliefs; therefore, (2) if all beliefs are truthful, there are [per (1)] false beliefs; (3) if not all beliefs are true, there are imitation beliefs; (four) therefore, either way, at that place are false beliefs (169d–170c). The being of false beliefs is inconsistent with the homo-mensura doctrine, and hence, if in that location are faux behavior, Protagoras' "truth" is false. But since the homo-mensura doctrine proclaims that all beliefs are true, if there are faux beliefs, and so the doctrine is manifestly untenable. The latter part of Socrates' second critique is much bolder—beingness called by Socrates "the most subtle statement"—equally it aims to undermine Protagoras' own commitment to relativism from within the relativist framework itself (170e–171c). At the beginning of this critique Socrates asserts that, according to the doctrine under attack, if you believe something to be the case but thousands disagree with you nearly it, that thing is true for you but false for the thousands. So he wonders what the case for Protagoras himself is. If not even he believed that human being is the mensurate, and the many did not either (as indeed they practise not), this "truth" that he wrote nearly is true for no one. If, on the other hand, he himself believed it, but the masses do non agree, the extent to which those who do not recall then exceed those who practise, to that same extent it is not so more than it is so. After, Socrates adds his "nearly subtle" bespeak: Protagoras agrees, regarding his own view, that the opinion of those who think he is incorrect is true, since he agrees that everybody believes things that are so. On the ground of this, he would take to hold that his own view is fake. On the other hand, the others practice not hold that they are wrong, and Protagoras is bound to concur, on the basis of his ain doctrine, that their conventionalities is truthful. The conclusion, Socrates states, inevitably undermines the validity of the Protagorean thesis: if Protagoras' opponents recollect that their disbelief in the man-mensura doctrine is truthful and Protagoras himself must grant the veracity of that belief, then the truth of the Protagorean theory is disputed by everyone, including Protagoras himself.

In the famous digression (172a–177c), which separates the 2nd from the 3rd statement against wide Protagoreanism, Socrates sets upwards a dichotomy betwixt the judicial and the philosophical realm: those thought of every bit worldly experts in problems of justice are blind followers of legal practicalities, while the philosophical mind, being unrestricted past temporal or spatial limitations, is free to investigate the true essence of justice. Borough justice is concerned with the here-and-now and presupposes a mechanical absorption of rules and regulations, whereas philosophical examination leads to an agreement of justice as an accented, non-relativistic value. This dichotomy between temporal and a-temporal justice rests on a more fundamental conceptual opposition between a civic morality and a godlike distancing from civic preoccupations. Godlikeness, Socrates contends, requires a certain degree of withdrawal from earthly affairs and an endeavor to emulate divine intelligence and morality. The otherworldliness of the digression has attracted the attending of, among others, Aristotle, in Nicomachean Ideals 10 seven, and Plotinus, who in Enneads I 2, offers an extended commentary of the text.

In his 3rd argument against broad Protagoreanism, Socrates exposes the flawed nature of Protagoras' definition of expertise, as a skill that points out what is benign, by contrasting sensible properties—such equally hot, which may indeed exist immune to interpersonal correction—and values, like the good and the beneficial, whose essence is independent from private appearances. The reason for this, Socrates argues, is that the content of value-judgments is properly assessed by reference to how things will plow out in the future. Experts are thus people who have the chapters to foresee the future effects of present causes. I may be an infallible judge of whether one is hot at present, merely just the adept physician is able accurately to tell today whether one will be feverish tomorrow. Thus the predictive powers of expertise bandage the last blow on the moral and epistemological dimensions of Protagorean Relativism.

In order to attack narrow Protagoreanism, which fully identifies cognition with perception, Socrates proposes to investigate the doctrine'south Heraclitean underpinnings. The question he now poses is: how radical does the Flux to which the Heracliteans are committed to must be in society for the definition of knowledge as perception to emerge every bit coherent and plausible? His answer is that the nature of Flux that sanctions Theaetetus' account must be very radical, indeed too radical for the definition itself to be either expressible or defensible. Equally nosotros saw earlier, the Secret Doctrine postulated two kinds of motion: the parents of the perceptual outcome undergo qualitative change, while its twin offspring undergoes locomotive modify. To the question whether the Heracliteans will grant that everything undergoes both kinds of change, Socrates replies in the affirmative because, were that not the example, both change and stability would be observed in the Heraclitean world of Flux. If then everything is characterized by all kinds of change at all times, what can nosotros say virtually anything? The answer is "zippo" because the referents of our discourse would be constantly shifting, and thus nosotros would be deprived of the power to formulate any words at all well-nigh annihilation. Consequently, Theaetetus' identification of knowledge with perception is deeply problematic because no unmarried act can properly be called "perception" rather than "non perception," and the definiendum is left with no definiens.

Afterwards Socrates has shown that narrow Protagoreanism, from within the ontological framework of radical Heracliteanism, is untenable, he proceeds to reveal the inherent faultiness of Theaetetus' definition of knowledge as perception. In his terminal and most decisive argument, Socrates makes the point that perhaps the nigh basic thought one can accept about two perceptible things, say a colour and a sound, is that they both "are." This kind of thought goes beyond the capacity of any one sense: sight cannot appraise the "existence" of sound, nor can hearing assess that of color. Amongst these "mutual" categories, i.east., categories to which no single sensual organ can afford access, Socrates includes "aforementioned," "different," "one," and "2," but also values, such every bit "off-white" and "foul." All of these are ascertained past the soul through its own resources, with no recourse to the senses. Theaetetus adds that the soul "seems to be making a calculation within itself of past and present in relation to hereafter" (186b). This remark ties in with Socrates' earlier attribution to expertise of the power to predict the hereafter result of nowadays occurrences. But information technology besides transcends that assertion in the sense that now a unmarried unified entity, the soul, is given cognitive supremacy, in some cases with the aid of the senses whereas in other cases the soul "itself by itself." Perception is thus shown to be an inadequate candidate for knowledge, and the discussion needs to foreground the activity of the soul when "it is busying itself over the things-which-are" (187a). The name of that activeness is judging, and it is to this that the second part of the chat now turns.

c. Knowledge every bit True Judgment (187a – 201c)

While truthful judgment, as the definiens of cognition, is the ostensible topic of the discussants' new round of conversation, the de facto topic turns out to exist false judgment. Judgment, as the soul's internal reasoning function, is introduced into the discussion at this juncture, which leads Theaetetus to the formulation of the identification of noesis with truthful judgment. Only Socrates contends that i cannot make proper sense of the notion of "truthful judgment," unless one can explicate what a false judgment is, a topic that also emerges in such dialogues every bit Euthydemus, Cratylus, Sophist, Philebus, and Timaeus. In order to examine the significant of "simulated judgment," he articulates five essentially abortive ways of looking at it: (a) false judgment as "mistaking one matter for another" (188a–c); (b) fake judgment as "thinking what is not" (188c–189b); (c) false judgment every bit "other-judgment" (189b–191a); (d) false judgment every bit the inappropriate linkage of a perception to a memory – the mind as a wax tablet (191a–196c); and (east) potential and bodily knowledge – the mind as an aviary (196d–200c).

The impossibility of fake judgment as "mistaking one thing for another" is demonstrated past the credible plausibility of the following perceptual claim: one cannot judge falsely that one person is another person, whether 1 knows one of them, or both of them, or neither one nor the other. The argument concerning false judgment as "thinking what is not" rests on an illustration between sense-perception and judgment: if one hears or feels something, at that place must exist something which one hears or feels. Too, if i judges something, there must exist something that 1 judges. Hence, one cannot judge "what is not," for one'south judgment would in that case have no object, one would gauge aught, and then would make no judgment at all. This and so cannot be a proper account of false judgment. The interlocutors' failure prompts a third try at solving the problem: mayhap, Socrates suggests, false judgment occurs "when a man, in identify of one of the things that are, has substituted in his thought some other of the things that are and asserts that it is. In this manner, he is always judging something which is, but judges 1 thing in place of another; and having missed the thing which was the object of his consideration, he might adequately be called 1 who judges falsely" (189c). False judgment and then is not concerned with what-is-not, but with interchanging one of the things-which-are with some other of the things-which-are, for case beautiful with ugly, just with unjust, odd with even, and moo-cow with horse. The absurdity of this substitution is reinforced by Socrates' definition of judgment as the final phase of the listen'south conversing with itself. How is it possible, then, for one to conclude one'south silent, internal dialogue with the preposterous equation of ii mutually exclusive attributes, and actually to say to oneself, "an odd number is fifty-fifty," or "oddness is evenness"?

The adjacent endeavour at explaining false judgment invokes the mental acts of remembering and forgetting and the ways in which they are implicated in perceptual events. Imagine the mind every bit a wax block, Socrates asks Theaetetus, on which we stamp what nosotros perceive or excogitate. Whatever is impressed upon the wax we remember and know, so long as the image remains in the wax; whatever is obliterated or cannot be impressed, we forget and do not know (191d-east). False judgment consists in matching the perception to the wrong imprint, e.g., seeing at a altitude two men, both of whom nosotros know, we may, in fitting the perceptions to the memory imprints, transpose them; or nosotros may match the sight of a man we know to the memory imprint of some other homo nosotros know, when we merely perceive one of them. Theaetetus accepts this model enthusiastically only Socrates dismisses information technology considering it leaves open the possibility of confusing unperceived concepts, such as numbers. 1 may wrongly think that 7+v = xi, and since 7+v = 12, this amounts to thinking that 12 is 11. Thus arithmetical errors call for the positing of a more comprehensive theoretical account of imitation judgment.

Socrates' side by side explanatory model, the aviary, is meant to address this particular kind of mistake. What Aristotle later called a distinction betwixt potentiality and authenticity becomes the conceptual foundation of this model. Socrates invites us to call back of the mind as an aviary full of birds of all sorts. The owner possesses them, in the sense that he has the ability to enter the aviary and catch them, simply does non have them, unless he literally has them in his easily. The birds are pieces of knowledge, to paw them over to someone else is to teach, to stock the aviary is to learn, to take hold of a detail bird is to recall a matter once learned and thus potentially known. The possibility of simulated judgment emerges when one enters the aviary in club to grab, say, a pigeon simply instead catches, say, a band-dove. To use an arithmetical example, one who has learned the numbers knows, in the sense that he possesses the knowledge of, both 11 and 12. If, when asked what is seven+five, one replies 11, one has hunted in i's memory for 12 just has activated instead i's knowledge of 11. Although the asylum's distinction between potential and actual cognition improves our understanding of the nature of episteme, it is soon rejected by Socrates on the grounds that it explains false judgment as "the interchange of pieces of knowledge" (199c). Fifty-fifty if one, following Theaetetus' suggestion, were willing to place in the aviary non only pieces of cognition just likewise pieces of ignorance—thereby making simulated judgment be the apprehension of a piece of ignorance—the question of false judgment would not be answered satisfactorily; for in that case, equally Socrates says, the human being who catches a piece of ignorance would still believe that he has caught a piece of knowledge, and therefore would behave as if he knew. To become dorsum to the arithmetical example mentioned earlier, Theaetetus suggests that the mistaking of 11 for 12 happens because the man making the judgment mistakes a slice of ignorance for a piece of knowledge but acts as if he has activated his capacity for knowing. The problem is, as Socrates says, that we would need to posit another aviary to explain how the judgment-maker mistakes a slice of ignorance for a piece of knowledge.

Socrates attributes their failure to explain imitation judgment to their attempting to do so earlier they have settled the question of the nature of noesis. Theaetetus repeats his definition of knowledge as true judgment but Socrates rejects it by means of the following argument: suppose, he says, the members of a jury are "justly persuaded of some matter, which merely an eye-witness could know and which cannot otherwise be known; suppose they come up to their determination upon hearsay, forming a true judgment. Hence, they have decided the case without knowledge, merely, granted they did their job well, they were correctly persuaded" (201b-c). This argument shows that forming a true opinion well-nigh something by means of persuasion is different from knowing information technology by an entreatment to the but method by means of which it can be known—in this case by seeing information technology—and thus knowledge and true judgment cannot be the same. After the failure of this attempt, Socrates and Theaetetus proceed to their last attempt to define knowledge.

d. Knowledge as True Judgment with Logos (201c – 210d)

Theaetetus remembers having heard that knowledge is truthful judgment accompanied by Logos (account), calculation that merely that which has Logos can be known. Since Theaetetus remembers no more, Socrates decides to help past offering a relevant theory that he once heard.

Co-ordinate to the Dream Theory (201d-206b), the world is equanimous of complexes and their elements. Complexes have Logos, while elements have none, but can only be named. Information technology is non fifty-fifty possible to say of an element that "it is" or "it is not," considering adding Being or non-Being to it would exist tantamount to making it a complex. Elements cannot be deemed for or known, but are perceptible. Complexes, on the opposite, can be known because one can have a true belief nearly them and give an business relationship of them, which is "essentially a circuitous of names" (202b).

Later Theaetetus concedes that this is the theory he has in listen, he and Socrates continue to examine information technology. In society to pinpoint the first problematic feature of the theory, Socrates uses the example of letters and syllables: the Logos of the syllable "so" – the first syllable of Socrates' name – is "s and o"; merely ane cannot give a similar Logos of the syllable'southward elements, namely of "s" and "o," since they are mere noises. In that case, Socrates wonders, how tin a complex of unknowable elements be itself knowable? For if the complex is simply the sum of its elements, and so the knowledge of it is predicated on knowledge of its elements, which is impossible; if, on the other hand, the circuitous is a "single form" produced out of the collocation of its elements, information technology volition notwithstanding be an indefinable simple. The only reasonable thing to say then is that the elements are much more clearly known than the complexes.

At present, turning to the fourth definition of noesis as true judgment accompanied by Logos, Socrates wishes to examine the pregnant of the term Logos, and comes upwardly with iii possible definitions. First, giving an account of something is "making one'south idea apparent vocally by means of words and verbal expressions" (206c). The problem with this definition is that Logos becomes "a affair that everyone is able to practise more or less readily," unless one is deaf or dumb, so that anyone with a true opinion would take knowledge as well. Secondly, to give an account of a matter is to enumerate all its elements (207a). Hesiod said that a carriage contains a hundred timbers. If asked what a railroad vehicle is, the average person volition most probably say, "wheels, beam, body, rails, yoke." Merely that would exist ridiculous, Socrates says, because it would be the same as giving the syllables of a name to someone's asking for an account of it. The ability to do that does non prevent the possibility that a person identifies at present correctly and now incorrectly the elements of the aforementioned syllable in unlike contexts. Finally, giving an account is defined as "being able to tell some mark by which the object you are asked well-nigh differs from all other things" (208c). As an example, Socrates uses the definition of the sun equally the brightest of the heavenly bodies that circumvolve the globe. Merely here again, the definition of cognition as truthful judgment with Logos is not immune to criticism. For if someone, who is asked to tell what distinguishes, say, Theaetetus, a man of whom he has a correct judgment, from all other things, were to say that he is a human being, and has a nose, mouth, optics, so on, his account would not help to distinguish Theaetetus from all other men. But if he had not already in his heed the means of differentiating Theaetetus from everyone else, he could not judge correctly who Theaetetus was and could not recognize him the next time he saw him. Then to add together Logos in this sense to true judgment is meaningless, because Logos is already role of true judgment, and then cannot itself be a guarantee of knowledge. To say that Logos is knowledge of the deviation does not solve the trouble, since the definition of knowledge as "true judgment plus cognition of the difference" begs the question of what knowledge is.

The definition of noesis as "true judgment plus Logos" cannot be sustained on any of the iii interpretations of the term Logos. Theaetetus has nothing else to say, and the dialogue ends inconclusively. Its accomplishment, according to Socrates, has been to rid Theaetetus of several false beliefs so that "if ever in the futurity [he] should endeavour to conceive or should succeed in conceiving other theories, they volition exist better ones as the consequence of this inquiry" (210b–c).

Despite its failure to produce a feasible definition of knowledge, the Theaetetus has exerted considerable influence on modern philosophical thought. Socrates' blurring of the distinction betwixt sanity and madness in his examination of cognition as perception was picked up in the starting time of Descartes' Meditations (1641); echoes of Protagorean Relativism accept appeared in important works of modern philosophy, such equally Quine'south Ontological Relativity and Other Essays (1969) and Kuhn's The Structure of Scientific Revolutions (1970); In Siris: A Concatenation of Philosophical Reflexions and Inquiries Apropos the Virtues of Tar-Water (1744), Bishop Berkeley thought that the dialogue anticipated the central tenets of his own theory of knowledge; in Studies in Humanism (1907), the English pragmatist F.C.S. Schiller saw in the section 166a ff. the pragmatist account of truth, get-go expounded and then condemned; and 50. Wittgenstein, in Philosophical Investigations (1953), found in the passage 201d–202b the seed of his Logical Atomism, consort too past Russell, and found it reminiscent of certain theses of his Tractatus Logico-Philosophicus.

iv. References and Farther Reading

a. General Commentaries

  • Bostock, D. Plato's Theaetetus. Oxford, 1988.
  • Burnyeat, Chiliad. F. The Theaetetus of Plato. Trans. M.J. Levett. Indianapolis and Cambridge, 1990.
  • Campbell, L. The Theaetetus of Plato. 2nd Ed. Oxford, 1883.
  • Cornford, F. G. Plato's Theory of Knowledge. The Theaetetus and the Sophist of Plato. Trans. F. Chiliad. Cornford. London, 1935.
  • McDowell, J. Plato: Theaetetus. Trans. J. McDowell. Oxford, 1973.
  • Polansky, R. Philosophy and Noesis: A Commentary on Plato's Theaetetus. Lewisburg, 1992.
  • Sedley, D. Due north. The Midwife of Platonism: Text and Subtext in Plato's Theaetetus. Oxford, 2004.

b. Cognition as Arts and Sciences

  • Burnyeat, 1000. F. "The Philosophical Sense of Theaetetus' Mathematics." Isis 69 (1978). 489–513.
  • Burnyeat, M. F. "Socratic Midwifery, Ideal Inspiration." Bulletin of the Institute of the Classical Studies 24 (1977). seven–xvi.
  • Santas, G. "The Socratic Fallacy." Journal of the History of Philosophy 10 (1972). 127–41.

c. Knowledge as Perception

  • Bolton, R. "Plato's Distinction between Beingness and Condign." Review of Metaphysics 29 (1975/6). 66–95.
  • Burnyeat, M. F. "Protagoras and Cocky Refutation in Plato's Theaetetus." Philosophical Review 85 (1976). 172–95.
  • Burnyeat, Grand. F. "Plato on the Grammar of Perceiving." Classical Quarterly 26 (1976). 29–51.
  • Burnyeat, Chiliad.F. "Idealism and Greek Philosophy: What Descartes Saw and Berkeley Missed." Philosophical Review 90 (1982). 3–xl.
  • Cole, A. T. "The Apology of Protagoras." Yale Classical Studies 19 (1966). 101–18.
  • Cooper, J. Thou. "Plato on Sense Perception and Knowledge: Theaetetus 184 to 186." Phronesis 15 (1970). 123–46.
  • Lee, E.N. "Hoist with His Own Petard: Ironic and Comic Elements in Plato's Critique of Protagoras (Tht. 161–171)," in Eastward.N. Lee and A.P.D. Mourelatos (eds.) Exegesis and Argument: Studies in Greek Philosophy Presented to Gregory. Vlastos. Assen, 1973. 225–61.
  • Matthen, M. "Perception, Relativism, and Truth: Reflections on Plato's Theaetetus 152 – 160." Dialogue 24 (1985). 33–58.
  • McCabe, M.M. Plato and his Predecessors: The Dramatisation of Reason. Cambridge, 2000.
  • Modrak, D.K. "Perception and Judgment in the Theaetetus." Phronesis 26 (1981). 35–54.
  • Rowe, C.J. et al. "Knowledge, Perception, and Memory: Theaetetus 166B." Classical Quarterly 32 (1982). 304–half dozen.
  • Silverman, A. "Flux and Language in the Theaetetus." Oxford Studies in Aboriginal Philosophy 18 (2000). 109–52.
  • Waterlow, S. "Protagoras and Inconsistency." Archiv für Geschichte der Philosophie 59 (1977). 19–36.

d. Knowledge as True Judgment

  • Ackrill, J. "Plato on False Belief: Theaetetus 187–200." Monist 50 (1966). 383–402.
  • Burnyeat, G.F. and J. Barnes, "Socrates and the Jury: Paradoxes in Plato's Distinction Between Knowledge and True Belief." Aristotelian Society Supplementary Volume 54 (1980). 173-91 and 193–206.
  • Denyer, N. Language, Thought and Falsehood in Ancient Greek Philosophy. London, 1991.
  • Lewis, F.A. "Foul Play in Plato's Asylum: Theaetetus 195Bff," in E.Due north. Lee and A.P.D. Mourelatos (eds.) Exegesis and Argument: Studies in Greek Philosophy Presented to Gregory. Vlastos. Assen, 1973. 262–84.
  • K.B. Matthews, Grand.B. "A Puzzle in Plato: Theaetetus 189b–190e," in David F. Austin (ed.) Philosophical Analysis: A Defense by Example. Dordrecht, 1988. three–fifteen.
  • Rudebusch, Thou. "Plato on Sense and Reference." Listen 104 (1985). 526–37.
  • C.F.J. Williams, C.F.J. "Referential Opacity and False Belief in the Theaetetus." Philosophical Quarterly 22 (1972). 289-302.

e. Cognition as True Judgment with Logos

  • Annas, J. "Knowledge and Language: The Theaetetus and the Cratylus," in Malcolm Schofield and Martha C. Nussbaum (eds.) Language and Logos: Studies in Ancient Greek Philosophy presented to One thousand.E.L. Owen. Cambridge, 1982. 95–114.
  • Fine, G.J. "Noesis and Logos in the Theaetetus." Philosophical Review 88 (1979). 366–97.
  • Gallop, D. "Plato and the Alphabet." Philosophical Review 72 (1963). 364–76.
  • Morrow, 1000.R. "Plato and the Mathematicians: An Interpretation of Socrates' Dream in the Theaetetus." Philosophical Review 79 (1970). 309–33.
  • Ryle, G. "Letters and Syllables in Plato." Philosophical Review 69 (1960). 431–51.

Author Information

Zina Giannopoulou
Email: zgiannop@uci.edu
University of California, Irvine
U. S. A.