What did Socrates train for?


1The scene serves to prepare for the conversation about the knowledge, albeit in a very reserved manner. We only learn that shortly before his death Socrates had a conversation with the young theate that is available in writing and is now to be read aloud. What the conversation was about is not yet revealed.

2However, we receive three interesting pieces of information about the alleged author Eukleides: firstly, he put a lot of effort into it, secondly, he decided on a certain form, thirdly, however, he was not quite finished.

3142c8-143a5 Eukleides on the genesis of dialogue. Eukleides has, as he says, the "speeches" (logoi), 1 which were kept in Athens at the time, and has the scrolls at hand to have them read aloud. What is remarkable is the complicated genesis of the text read, about which Plato Eukleides briefly reports. He had not been present at the conversation, but had heard Socrates tell him about it on a visit to Athens, after which he made notes at home in Megara and later worked them out in peace. On further visits to Athens, he asked Socrates about places where his memory failed him, and when he returned home he added or corrected the text accordingly. The text is said to have been created little by little in painstaking work

4One can ask why Plato describes the genesis of the dialogue in such detail. Does he want to explain to his readers how tedious it can be to write Socratic dialogues and give an insight into his own way of working? The Theaetetus is in any case far too complicated in terms of form and content to be simply written down in one go. There must have been preliminary work and intermediate stages.

5It is also noteworthy that, according to Eukleides' account, no review of the text by Socrates took place. So Eucleides wrote down what he heard from Socrates to the best of his knowledge and, as the author, is solely responsible for the result. Accordingly, Plato could say of himself that he wrote down in his dialogues what he learned in dealing with Socrates, but could not and would not claim to represent his authentic views.

6Is it not Plato but Eukleides who is the real author? Plato seems in some ways different from his Theaetetus to distance; because when he makes Eukleides the author, he declares the text read aloud as a quotation. Eukleides would then be responsible for the wording of the dialogue on knowledge. If one takes this literally, one could argue about whether Plato is reproducing or fabricating a real dialogue of the Euclid, as it was in the Phaedrus there is a discussion whether the alleged Lysias speech read there really comes from Lysias or is an invention of Plato. Now nobody will believe that we are actually dealing with a dialogue by the megaric Eukleides, but perhaps one should investigate the question of what that is Theaetetus differs from Plato's other dialogues. In any case, it is striking that Socrates only discusses the opinions of others here. It is possible that Eukleides' dialogues provided the model for this kind of representation of Socrates.

7143a5 "almost entirely". What does Plato mean when he lets Eukleides say that the conversation is now "almost entirely" in written form? Does that mean that Plato was not satisfied with himself and felt his own Theaetetus as unfinished?

8 In some places the train of thought can actually be improved.3 There are also cases where preliminary notes seem to have not yet been incorporated.4 Towards the end of the dialogue, a meaning of "perception" is introduced, which actually means a revision of the discussion about Theätet's second answer ( i.e. of the entire section 151e1-186e12). 5

9143b5-c6 That im Theaetetus Reading a dialogue is not an uncommon practice in itself. in the Protagoras Socrates tells a friend about a long conversation he had with Protagoras. But there is a not insignificant difference: Eukleides says that when writing his text he left out the constant "I said" and "he answered", which Socrates was forced to as narrator, and thus turned the narrated dialogue into a direct dialogue. For Plato's readers, this brings the conversation back to the present. We are inclined to agree with Terpsion, not only because it is a formal simplification, but above all because it creates the illusion that we are directly there as listeners.

However, the procedure also has a disadvantage: there are no additional commentaries by the narrator Socrates as in Protagoras. We only learn what he says and not what else he observes and thinks during the conversation

By the way, this creates a technical problem for the reader who must now indicate every change of speaker on his own, for example by changing the pitch of the voice. That the servant (slave) commissioned by Eukleides can do this apparently to the satisfaction of his listeners, we can take note of respect.

12If the change of speaker is not made clear by "said he" and "said I", it must be visually marked differently in the text for the reader or reader. While it is customary in our editions and translations of Plato's dialogues, as in our dramatic texts, to insert the person's name every time, Plato probably contented himself with separating dashes. So that readers or readers and listeners do not forget who is speaking, people speak to each other by name from time to time to be on the safe side.

13Im Theaetetus there is a special case: the reader only learns at the very end of the Megara scene that the previously anonymous speaker and alleged author of the text to be read is called Eukleides (143c7).

14Socrates is sitting with the mathematician Theodoros in a sports facility where young people are doing their exercises. Apparently Theodoros has just told about his lessons in Cyrene.

15143d1-144d7 E.Introductory conversation between Socrates and Theodoros.

In response to Socrates' question about the outstanding talents among his students in Athens, Theodorus names one who is outwardly "ugly", but of an "astonishingly good nature". He understood everything more quickly than anyone else, but was at the same time particularly calm and of an unusually firm character.

17This creates a starting point for the subsequent conversation with Theätet; for Socrates would of course now like to get to know the young person better. Just as the scrolls were readily available in the Megara scene, Theätet now happens to be nearby and is summoned by Theodoros.

18 "Kyréne". From this passage it does not emerge - contrary to what is often assumed - that Theodoros came from Cyrene in Africa, but only that he gave lessons there as a traveling sophist.

19143e8 "not nice". Theodoros wants to ward off the suspicion that his subsequent, extremely positive judgment about Theätet may be irrelevant and not to be taken seriously. Behind this stands the contrast between external ugliness and internal beauty, about which Alcibiades in his eulogy of Socrates im Symposium talks.

20 This aesthetically embarrassing contradiction is shown in the Theaetetus dissolved by Plato through the devaluation of the body compared to the soul. The body / soul contrast plays an important role later in the conversation about knowledge.

21144a6-b2 With this little digression about the rare compatibility of actually opposite properties, Theodoros recommends, one could say, that Theätet be included in the rank of "guardians" in Plato's state (Politeia 375b).

22144d8-146c2 Introductory conversation between Socrates and Theätet. Socrates introduces further keywords for the conversation about knowledge.

23 "examine" (144e3, 145b3, b7). Contrary to what it looks like at first, Socrates does not want to hold an intelligence and character test with Theätet, but wants to examine together with him what knowledge is. "Layman / Expert" (144e3-145a10). The distinction becomes important when dealing with Protagoras. Compare to 166c9-167d5.

24 "body / soul" (145a11-b2). The pair of terms is assumed by Socrates, as it is customary to this day, to be given by nature and used to distinguish between sensory perception and thinking. Compare to 184b7-185a7, 185d3.

25 "learn" (145d7f.). As a transition between not-knowing and knowing, learning seems to participate in both, which sophistic formalists interpreted as a contradiction. Compare to 188a1-c9, 191c3-6.

26 "Knowledge" and "Knowledge" (sophía and epistéme, 145d11-e6). Differentiating these terms is difficult because it is not clear how they differ, and the two words sometimes have the same meaning. Compare to 146d7-147c6. Probably was sophía common in colloquial language while epistéme for Socrates it is more of a philosophical technical term.

27146a1-5 Since Plato is in reality not about the act, but rather the question "What is knowledge?" his Socrates may undertake the surprising attempt to set an apparently popular parlor game in motion: someone asks a question (or poses a riddle); whoever knows the correct answer is "king" and can ask the next question. After answering his question "What is knowledge?" and his request "Who of us will say it?" Nobody has replied, Theodoros makes a counter-proposal: Socrates should conduct a regular dialogue about this with Theätet, with whom he has already started a conversation, and give him the role of the 'answerer'. That theätet should be examined is forgotten. Accordingly, Socrates can later use Theodoros instead of Theätet as the 'answerer'.

28146c7-151d3 Theätet's first answer: "Insights are both math ... and shoemaking ... "

29146c7-d5 Theätet refers to the usage of language. Plato has Theätet list examples of "knowledge". Socrates reacts ironically (as usual when someone answers a question of definition with a list of examples) and says that Theätet is generous and generous

30 "a lot" (pollá) and "different" (poikíla)

31 presented, which makes the answer appear superficial and unthought-through - and seduces the reader to agree with this criticism.7 Theätet seems to have not understood the question and, moreover, is talking indiscriminately about cabbage and turnips. In reality, Socrates is doing him an injustice; because his question "What is knowledge?" is so general and indeterminate that many and varied answers are possible.

The list of examples, i.e. the reference to the use of language, is actually the closest and most important answer, because it would first have to be clarified in principle what is meant by the question and what is understood by "knowledge" in common language use. Theätet's answer therefore deserves more careful consideration than it has hitherto received from research on Plato

33 Theätet distinguishes between two types of knowledge, firstly the subjects previously listed by Socrates (145c-d) in which Theodoros taught, i.e. mathematics in the broader sense of the time, and secondly handicrafts (téchnai) like shoemaking.

34If there is something to criticize about Theätet's answer, it is not the listing of examples, but the ambiguity of "knowledge" (epistéme). The theoretical knowledge of mathematicians and the practical knowledge of craftsmen are on the one hand both called "findings" (epistêmai), on the other hand they are called "knowledge" (epistéme) and can" (téchne) differentiated, i.e. epistéme serves both as a generic term and a sub-term9

epistéme || techne

36 It would of course be better if theätet had a different name for the generic term, e.g. sophía, would have used. That he does not, however, corresponds to the linguistic usage at the time; for the examples show that, on the one hand, knowledge was ascribed to all activities that were not very simple, but on the other hand, theoretical and practical activities were distinguished as knowledge and ability. We are also of the opinion today that a craftsman must have knowledge, and by that we mean knowledge and ability. In everyday language, the ambiguity of "knowledge" (epistéme) acceptable because the context usually shows what is meant.

37 If Plato had formulated Theätet's answer as a thesis-like definition, it could read:

"Epistéme is a word that denotes a thing (a concept),
for which there is no fixed term in the Greek language, but rather
several names - epistéme, sophía, gnôsis, máthesis
i.a. - gives. "

38 Socrates would then have to apologize for the ambiguity of his question and say that he did not have the floor epistémebut rather the thing signified by it.

39146d7-147c6 What does Socrates want to hear? If Theätet, as Socrates says, has offered "many and varied", this could actually lead to a discussion about the variety of examples and the use of language - and also about the ambiguity of epistéme - surrendered. But Plato does not go into it; because he wants Socrates and Theätet over the "epistéme himself "(146e9). So Socrates does not ask how the word is used epistéme, but rather according to the thing that is denoted by this word, but "itself" is only vaguely known.

In doing so, he is not interested in the formal unity of this "self", i.e. the formally summarizing generic term that contains all special knowledge such as that of the mathematician and shoemaker, but in its factual unity. His reasoning is: "Anyone who does not know what knowledge is in itself cannot understand what knowledge is in individual cases." Theätet should therefore give him an explanation of the content and say "what that is". So Socrates wants information about the actual "being" or "essence" of knowledge

When Socrates specified his question in this sense, Theätet might actually react angrily ("You should have said that right away"), but since he is young and humble, he makes the abrupt transition from linguistic usage to the Socratic question of being, which almost amounts to changing the subject. without hesitation. As a reader one may ask whether Plato himself would have followed his teacher Socrates so easily and would not have asked him to go further into the problem of language and language use.

According to current ideas, what Theätet is supposed to deliver requires longer explanations. But Socrates wants a very short answer and gives as an example: "Clay is damp earth." A term that requires explanation ("clay") is defined by another that is assumed to be known ("moist earth"). Socrates would like an analogous statement for "knowledge", so "knowledge is x." Theätet should substitute a known word or a short formula for x, which explains "knowledge".

43 Theet could now answer: "epistéme is sophíaSocrates had previously equated the two with one another (145e6), and Theätet can therefore assume that Socrates knows what sophia is. When Socrates replied that he only had a rough idea of sophia, What sophia he doesn't know, the question "what is." sophia?" be continued.

44 Socrates' desire to summarize possibly very complex facts in a succinct formula is based on the idea that the general (the generic term) must be simpler than the individual, because all differentiations are omitted.11 In terms of dialogue strategy, the purpose here is to find the answerer To force a short thesis-like answer, which is then to be investigated. The question "What is knowledge?" thus becomes the starting point for a heuristic dialogical procedure in which the answerer Theätet serves as a key word in the following with three theses.

45Before Theätet comes to the first thesis ("Knowledge is Perception" 151e3), two digressions follow: Theätet reports on a mathematics lesson with Theodoros, in which, he believes, they would have done what Socrates now demands, and Socrates explains his "midwifery".

46147c8-148b3 Theätets example from math class. Socrates asked Theätet to summarize the knowledge he had enumerated under an umbrella term. In order to make sure whether he understood Socrates correctly, Theätet mentions a similar case from a mathematics lesson: Theodoros used a drawing to present a series of incommensurable lines, which they then call "possibilities" (dynámeis) had summarized.

47 Socrates accepts the comparison: just as certain lines can be grouped into a class, theätet should combine the many findings into a general term and give it a name.

48147d4-148b3 Digression: A mathematics lesson with Theodoros.

49 Theätet briefly reports how Theodoros and his pupils proceeded. In this context, only the example itself matters. If it had been about teaching zoology, Theätet might have said: "We have talked about donkeys, cattle, sheep and goats and have summarized them under the term" cattle ".

50 For more details on the mathematics lesson, see Appendix 1.

51148e1-6 Theätet is unable to come up with a common term and name for the knowledge cited by him (mathematics, etc.)eidos and logos) to find. Although he had often thought about it, because he had heard of "such questions constantly asked by Socrates", he had not come to any conclusion and had not heard any satisfactory answer from anyone else.

52Since he was already asking "What is knowledge?" and knows what role Socrates' questions ("What is ...?") play in contemporary discussion, he could actually have known that Socrates would not accept his reference to the use of language as an answer. But Plato would like to pose the question of knowledge as deeply disturbing and even causing pain, so that Socrates can refer to his role as obstetrician.

53149a1-151d3 Socrates as midwife and cook.

54 Socrates explains the role he plays in contemporary discussion. Since he does not claim to know anything, he does not offer lessons, but "being together" (syn-ousía 150d4, 151a2). He does not want to teach, but to question supposed knowledge and thereby stimulate independent thinking. He succeeded in doing this with some who accepted it (150d4-8), while others went astray (150e1-7). Still others who were not interested in philosophy but in specialist knowledge were referred to appropriate teachers (151b1-6).

55 The comparison with a midwife is intended to clarify his method, but like all comparisons does not fit in every respect. As is usually the case with Plato, the two semantic levels are not sharply separated, i.e. comparison and matter should explain each other.

Just as the midwife should have given birth to children, so Socrates has her own experience in thinking. As a midwife, the midwife does not want to give birth to her own children, Socrates does not want to present his own knowledge, but rather to bring the half-baked thoughts12 of others to light in a dialogue. Just as an unborn child causes labor pains, unexplained thoughts (aporias) cause mental agony.

57If Socrates thinks that midwives do not have to have a "certificate" for newborns (eídolon) and "truth" (150a9-b4), the terminology shows that he actually means thinking and not having children; for he cannot, of course, doubt that midwives can see whether a newborn is misshapen or not (151c3-5).

58 Even his claim that midwives would be the best matchmakers if they were willing to do so (149d5-150a7) only makes sense if he does not mean the midwives, but rather his own ability to find the right teachers for potential students.

On one point the comparison fails altogether; for Socrates not only wants to bring to light thoughts that theätet carries within itself like unborn children, but also, so to speak, presents foreign children to him for assessment, such as the epistemology of the sophist Protagoras. That's why he compares himself to one cook, who offers food to Theätet for tasting and wants to know whether he likes it (157c-d). As an obstetrician, he prompts Theätet to name relevant heuristic theses; As a cook, he puts his own or other people's theses up for discussion.

60 Socrates' goal in Theaetetus is to find out together with Theätet what is behind the term "knowledge" (epistéme) and how one can come to clear terms and perhaps even a simple definition by analyzing and structuring this conglomerate of ideas.

In making a comparison with a midwife, Socrates almost casually addressed aspects that further determine his question of knowledge: the disjunction "body / soul" (150b8-9), "thinking" (diánoia 150c2), "true" (150b3, c3, 151d3).

62151e1-186e12 Theätet's second answer: "Knowledge is perception."

63This section is considerably longer than the following two, because between the formulation of the thesis (151e1-7) and its actual investigation (184a9-186a12) a section (152a1-183c7) is inserted, in which Socrates goes in detail on the epistemological ideas of the Sophists Protagoras and his followers enters. Starting with the sentence "Man is the measure of all things" (Homo-mensura sentence), Socrates comes to speak of Heraclitus' flow theory and a special theory of perception. In the further course Protagoras is criticized, but also defended again, with Socrates representing the deceased Protagoras as spokesman. In between, Theodoros took on the role of the answerer instead of Theätet (168c8-183c7). An "excursus" on philosophy (172b8-177b7) culminates in Socrates' evocative reference (176b1) to the "resemblance to God", for him the real goal of every genuine philosopher.

64151e1-7 | | 184a9-186e12 Conversation about Theätet's answer

65152a1-172b8 | | 177b5-183c7 Conversation about Protagoras

66172b8-177b7 Digression on philosophy

67151d7-e6 "Knowledge is perception", a paradoxical thesis. Socrates had asked Theätet to substitute something for x in the formula "Knowledge is x", which explains what knowledge is, and Theätet would have "Knowledge (epistéme) is knowledge (sophia) "13 But instead Plato puts a thesis in his mouth that appears out of nowhere, so to speak. It is paradoxical because every normally thinking person believes he knows that knowledge and perception are not the same Thoughts arise that someone who sees a shoe also has the knowledge to be able to manufacture a shoe?

68This provocative thesis is obviously not a spontaneous idea of ​​the young theate, but Plato has him quote a definition from the contemporary discussion, as explicitly with the two following theses.14 It had not remained unchallenged; for Socrates knows a sophistic counter-argument (cf. on 163c6-164b12).

69What is meant by the thesis? Theätet indicates how he himself understands the thesis:

"The knower perceives what he knows."

In his opinion, knowing and perceiving are two different things, but they are somehow related. For him, perception seems to be the preliminary stage of knowledge. He could give the examples used in his first answer: an astronomer observes the stars and then ponders them; the shoemaker looks at a piece of leather and then thinks about how to make a shoe from it.

71But since it is not possible to say exactly where perception ends and where reflection begins, it is not as easy to distinguish between perception and knowledge as it looks after the unreflected use of language.15 In the sense of 'reception' they can even be interchangeable, that is, to be identical.16 The thesis is only paradoxical if knowledge is understood not to be reception, but rather to be thought, that is, whoever sees a shoe also knows how to make it.

72 Socrates does not go into the differentiation contained in Theätet's preliminary suggestion, but sticks to the paradoxical wording of the thesis. In the following, he therefore constantly works with the equation "knowledge = perception" .17 With this he assumes that Theätet has asserted identity, which of course makes it easy for him to refute this paradoxical 'identity thesis'.

If Socrates had listened to Theätet more closely, he might have realized that Theätet was unconsciously in the process of distinguishing between reception and thought, and that perception and knowledge are only identical if both are understood in the sense of reception. If, on the other hand, perception is a sub-concept of knowledge, one can only speak of partial identity. The equation "knowledge is perception" is therefore ambiguous; for it can be understood to mean complete, but also partial identity, which Socrates does not seem to pay attention to here or later.

74This ambiguity is already to be found in natural language; because "is" can mean both complete and partial identity (= "is also"). This also applies to the emphatic "is nothing else than".

75151e8-152a2 transition to Protagoras. Socrates also finds this not exactly defined correspondence between knowledge and perception in Protagoras. He therefore believes he can say that the latter represented the thesis "knowledge is perception" in his book, 18 and now turns to him.

From a strategic point of view of the dialogue: Plato wants to introduce additional discussion material into the conversation, which Socrates, like a cook, offers the young theater to taste.

77152a2-183c7 The conversation about Protagoras.

78 Socrates has only just announced that he wants to "examine Theätet's thesis" with him "(151e5) when he is already moving on to the Homomensura sentence of Protagoras. According to Socrates, the theses should

"Knowledge is perception"


"Man is the measure of all things"

80 mean about the same thing, and he then seems to treat them in parallel. In any case, he establishes interim results and a final result for both of them together. According to a first presentation of the doctrine of Protagoras, it says accordingly (160d5-e2):

"The investigation has proven both theses to be correct."

81After a critical examination, the sobering revocation follows (164d8-10):

"The investigation has proven both theses to be wrong."

After a renewed examination, Socrates is inclined to at least partially accept both theses (179c2-d1):

"Both theses seem to be correct somehow."

83Finally, he summarizes again (183b6-c2):

"Both theses are somehow wrong."

84But if one takes a closer look at the conversation, one has to say that while Socrates kept Theätet's thesis in mind, it only considered it indirectly in connection with Protagoras and only went into it directly afterwards.19 The transition is explicitly marked by Socrates (Plato) (184a9-b2):

"We have to give birth to what Theätet is pregnant with."

So Socrates only now wants to examine Theätet's thesis himself and clarify whether it will stand up to critical scrutiny. From now on Protagoras is no longer mentioned.

The part dedicated to Protagoras is too complicated in terms of form and content to be reduced to an easily comprehensible scheme. A free dialogue structure and a certain factual confusion, 20 which probably goes back to the loose arrangement in Protagoras' book, have entered into a not entirely happy relationship.21 In general, however, one can orientate oneself on the following structure:

87 (1) Socrates presents Protagoras' epistemology. 152d-160e

Excursion: amazement as the beginning of philosophy. 154b-155d

89 (2) He criticizes Protagoras. 161c-165e

90 (3) His "help" for Protagoras. 165e-168c

91 Fingered speech by Protagoras. 166a-168c

92 (4) Socrates continues his criticism (with Theodoros). 169d-183b

93 Excursion: Rhetoric and Philosophy. 172b-177e

94 (5) His conclusion: Measure is only the "reasonable" (phrónimos). 183b9

95 In what he says about Protagoras, Socrates seems to be referring primarily to his book on the truth to support. At the same time, however, he invokes a teaching that Protagoras reserved for his students (cf. on 152c10). It is therefore difficult to distinguish what was in the book and what Socrates got from elsewhere or interpreted into it on his own initiative. In addition, he often only quotes Protagoras as a member of a group (cf. on 152e1-5), so that it is open whether we are dealing with himself or with a widespread contemporary school of thought.

96 Platon probably lets his Socrates say about Protagoras what the intellectual public thought of him after the death of the famous Sophist (around 415 BC). We can take it for granted that he also had Protagoras' book before him. It is, however, rather doubtful whether he studied it exactly word for word; for the rendering by Socrates sometimes seems somewhat generalized and fleeting. 22

97 Protagoras appears in his book - about his own truth, to support the homo mensura sentence - have drawn on everything that circulated in philosophical opinions in his time, from general world interpretation and cosmology to special theories and individual thoughts. He didn't ask much about whether these could be real arguments for him or just decorative set pieces. And it was certainly not about presenting the opinions of others correctly and classifying his sentence in terms of the history of philosophy. One need therefore not be surprised if some of the things Socrates said seem far-fetched and are not always compatible with one another. As an experienced speaker, Protagoras knew that sometimes more can be achieved through rhetorical effort than through concentration on the problem under discussion. 23

It is impossible to tell whether Plato did not see through the game or whether he is consciously participating. In the second case he would have done well to somehow ask the reader to distinguish between thing and decoration. So the 'flow theory' (which actually contradicts the Homo-mensura-sentence24) haunts Socrates' presentation in its general and radical form, which fakes complications to the reader that in reality do not exist.

According to Socrates' account, Protagoras let the prehistory of the Homo-mensura-theorem begin in prehistoric times. Socrates accompanies him on the path from Homer to a specialist theory of perception, without asking whether some things are not only superficially linked, such as Heraclitus 'flow theory, Empedocles' cosmology, a general theory of movement and various individual contributions to the problem of relativity and especially that Relativity of all perception. Obviously, in the contemporary discussion, everything that Protagoras had made use of was somewhat mixed up. Socrates does not criticize this; In the end, he is only concerned with the question of whether or to what extent one has to recognize the homo-mensura sentence or not.

There are also concrete indications that Plato as a whole broadly followed the text of Protagoras' book. Socrates' presentation shows the typical features of a summarizing report, which, although it reproduces the individual steps of the original as a whole, often leaves out justifications and intermediate stations. So he changes the terminology several times without motivation25 or repeats something without it being clear from his presentation why he is doing this. Sometimes he seems to have skipped links so that the reader has to add one or the other to himself

101152a1-160e5 Socrates represents Protagoras' epistemology.

102 Socrates quotes the homo-mensura sentence and claims that it means in a way the same thing as Theätet's thesis "knowledge is perception". This is followed by his presentation of Protagora's teaching. He begins with the flow theory and then shows the subjectivity of all perception, first on the basis of a special perception theory, then by reference to the experience (dreams and illness).


104 (1) Homo mensura sentence 152a2-4

105 (2) Equation with Theätet's thesis 152a6-c7

106 (3) Flow Theory 152c8-153d7

107 (4) subjectivity of perception ("for me") 153d8-160d4

  • Perceptual theory
  • Experience: dreams, illness
  • subjective and objective truth

108 (5) Conclusion: general agreement 160d5-e2

Section (4) is even more complicated in detail, mainly because the theory of perception is presented in two versions and two sophistic paradoxes (*) have been inserted that unnecessarily interrupt the train of thought:

110 (a) Theory of Perception (first version) 153d8-154a9

111 * "Change without change?" 154b1-155d5

112 Perception theory (second version) 156a3-157c3

113 (b) dreams 157e1-158e4

114 * "different" and "completely different" 158e5-159c10

115 Health and Disease 159c11-e6

116 (c) subjective and objective truth 159e7-160d4

117152a2-4 The homo mensura sentence. Socrates quotes the sentence of Protagoras in its complete form:

"Man is the measure of all things,
of the being that / as they are,
of the non-being that / as they are not. "27

118 Later he also uses the short form (170d) that has been in use since then in the same sense:

"Man is the measure of all things." 28

Taken on its own, the sentence sounds like an oracle that hides supposed or real knowledge behind intentionally dark words.As the beginning of a philosophical book, it is suitable to provoke and arouse interest. The reader has to ask himself: What is meant by "measure" and why should the "human being" be measure?

With his sentence, Protagoras, as already said, paraphrases the paradox that lies in the distinction between subject29 and object and in the concept of reception. The subject plays a double role. It receives, but is at the same time the "measure" of reception, i.e. it judges it like an "arbiter" (160c8) and determines - one could also say like a sieve or filter - the type and extent of reception. The proposition of Protagoras could therefore be:

"The receiving subject is at the same time the filter of things."

121 Since Protagoras probably didn't have a word of its own for "reception" and instead "perception" (aísthesis), 30 should have found somewhere in his book the following sentence:

"Perception is the measure of all things."

122 Humans only perceive what they perceive. This tautological-sounding formulation expresses that man cannot ignore himself. If he does not perceive a thing, he neither knows whether it exists nor what it looks like. And when he perceives something, he cannot escape from his perception, but remains trapped in it. We cannot therefore know how things are in themselves, because they are only accessible to us through our perception and are filtered through them. This is not a metaphysical problem, it is part of the concept of reception. Reception does not mean that the object is eaten by the subject like a mouse is eaten by a cat, i.e. that it is directly absorbed itself, but that a relationship comes about on a different semantic level.

The sense of the homo-mensura sentence is: Since actual knowledge presupposes direct access to the object, there can be no absolute knowledge for humans. Protagoras could therefore have said somewhere in his book:

"There is no knowledge, only perception."

124This agrees with Socrates' view of Theätet's thesis, and therefore he can claim that Theätet said the same as Protagoras said with the homo-mensura sentence (152a).

It is an ancient insight that perceptions are relative because they are influenced by the subject (the state of the perceiving person). Homer already knew that. When the singer Demodokos sings a song to the Phaeacians, King Alcinous notices - because Odysseus bursts into tears (Odyssey 8, 94) - that it sounds different to the guest than to the rest of the audience. Protagoras only recognized the underlying principle and formulated it powerfully.

As can be seen from Socrates' further presentation, Protagoras related the homo-mensura sentence not only to "perception" but also to "opinion" (doxa) of man.31 For man, the opinion that he has and that he considers to be correct is inevitably the standard by which he is orientated. Protagoras could therefore also have said:

"The opinion (doxa) man is the measure of all things ".

127 Man is dependent on his doxa, which he has formed on the basis of his perception. 32 The patient perceives sweet wine as bitter, i.e. he thinks it is really bitter.

128 As we can also see from Socrates' account, Protagoras often referred to "showing himself" (phainesthai) spoke of things33 and could therefore have formulated his sentence accordingly:

"Showing oneself is the measure of all things."

129We cannot perceive more of things than they show us. Every reception process has two sides. The subject perceives, the object is perceived. If one substitutes the active "showing oneself" for the passive "being perceived", that is just a different grammatical point of view, that means that the object is not assigned active action, but "showing oneself" is only the grammatical active role that that Object in perception plays.

130Platon would have made it easier for the reader if his Socrates had not tacitly taken over "showing oneself" from Protagoras' book, but had expressly pointed out that this is the same state of affairs that is otherwise referred to as "perceiving."

Besides, by doing so he would have acted as a pretext for a possible misunderstanding; because when it comes to the physical or physiological process of perception, things should really contribute actively to perception. 35

132 With his homo-mensura sentence, Protagoras summarized the dependence of people on their perception and opinion, and thus the subjectivity and relativity of knowledge, in a simple formula: The person as a subject is at the same time the recipient and filter of things

The sentence is unproblematic for Socrates as far as the relativization of perception and doxa is concerned, which even he does not trust. However, he is against extending the proposition with Protagoras to include knowledge. Actually, this is based on a misunderstanding; for Socrates does not seem to notice that by this he means something other than Protagoras. Protagoras thinks of scientific knowledge in today's sense, which is never definitively certain, but can be overtaken by new research. Socrates, on the other hand, thinks of absolute knowledge, which he hopes can be reached by man, if not in this world, at least in the hereafter.

134How could Schopenhauer overlook the homo-mensura sentence?

135 Schopenhauer's work The world as will and idea begins with the succinct statement:

"The world is my vision."

136Since "imagination" is what Protagoras means "Doxa", Schopenhauer could also have said:

"The world is my doxa."

137This is nothing other than the homo-mensura sentence in the form just mentioned:

"The human doxa is the measure of all things."

Strangely enough, there is no reference to the homo-mensura sentence in Schopenhauer. In the preface to the first edition he demands familiarity with the Kantian philosophy from the reader and also says that he would be even better prepared if he were "in the school of the divine Plato has stayed ". It is therefore all the more astonishing that Plato himself did not immediately Theaetetus and the sentence of Protagoras quoted there has occurred to me, especially since he explains on the next page: "This truth is by no means new", and in addition to Kant refers to Descartes, Berkeley and the Indian Vedanta philosophy and later to Plato Theaetetus cited several times.

As with Protagoras, Schopenhauer is concerned with the relationship between subject and object and "being conditioned by the subject" (§ 1). Some of his formulations - e.g. "the whole world (is) only an object in relation to the subject" - sound like paraphrases of statements that Socrates of Protagoras quotes, e.g. "something is only ever sweet for someone" (160b1-3).

140152a4-5 "read often". The book of Protagoras may not have played a role in Theodoros' mathematics lessons, but it must have been a general topic of conversation.

141152a6-c7 Socrates' equation of Theätet's thesis with the Homo-mensura-proposition.

When Theätet read the Homo-mensura sentence for the first time, it must have struck him as puzzling too, but when Socrates now quotes it, he must also ask himself what a sentence in which neither the word "knowledge" and "perception" occurs to have to do with his thesis "knowledge is perception". Socrates tries to explain it to him and claims that the homo-mensura-theorem leads to the equation

"show oneself = be"

In addition, 37 Theätet agrees without further ado, presumably because he himself had read this or something similar in Protagoras. Socrates seems to be referring to the book of Protagoras, but uses himself and Theätet as examples. The things (objects) are then as they appear to each individual subject ("you, me").

144This sounds as if, according to Protagoras, the being of things is directly accessible to man through their showing oneself, whereby Socrates is of course clear that Protagoras means the opposite, namely that being cannot be reached and we are content with showing oneself have to. In general, that doesn't bother us; we stick to the self-showing of things, take it for their being and do not ask about the 'thing in itself'. We only become aware of the problem in this when a thing appears differently to two people, e.g. a wind is perceived as warm by one and cold by the other. Then showing oneself turns out to be relative, and if one is of the opinion with Protagoras that man cannot get beyond showing oneself things, then in the equation "show oneself = to be" consequently "to be" is "just as relative as" to show yourself".

145The terms "show oneself" and "perceive" are interchangeable if only the different perspectives of object and subject are meant, and Protagoras / Socrates therefore comes to the equation:

"show oneself = perceive".

146If one now replaces "show oneself" by "perceive" in the first equation, one arrives at the statement:

"Perception is always the perception of beings".

But when perception reaches being itself, it cannot deceive, and one can say:

"Perception is always not-wrong (a-pseudés)".38

So far Socrates seems to be sticking to the book of Protagoras. He now substitutes "knowledge" for "not-wrong", and this results in the equation:

"Perception is knowledge".

149This, in his opinion, shows the agreement between the Homo-mensura sentence and Theätet's thesis. His thesis was "knowledge is perception", but since Socrates understands "is" in the sense of identity, he is allowed to swap the two sides. Compare to 151d7- e6.

150152c7 Theätet's answer is ambiguous because phaínetai can mean both “this is how it appears” and “this is how it appears ”.39 It remains to be seen whether Theätet will accept the evidence or react skeptically.

151152c8-11 Protagoras' alleged secret doctrine. What is meant is the flow theory. Compare to 152d2-153d7.

152With "all-knowing" (pás-sophos) Socrates increases the ironically respectful predicate "knowing" (sophós), which he often uses for learned sophists and respected poets, while he counts himself as part of the "great mass" or, like 154e3, among the "small people". With "truth", which here (like 155d10) means "the real meaning", Socrates alludes to the book's paradoxical title.

153152c10 (Relative) Truth. An allusion to the title Protagoras had given his book. The title was a typically sophistic provocation. Because Protagoras' truth consists in the assertion that in reality there is no truth for man. If things are not directly accessible to us, as the homo mensura sentence says, we cannot know the truth about them. So Protagoras wanted to prove in his book the opposite of what the title seems to promise.

154 It follows from the Homo-mensura sentence that no "perception" (aísthesis) or "opinion" (doxa) is refutable because one would have to know the truth. If one calls this non-refutability truth, all perceptions and opinions become true in one fell swoop. Of course, Protagoras did not escape the fact that he thereby relativized the concept of truth, because it is not an objective, but only a subjective and individual truth that can be objectively false. But if you take part in this game, as Socrates shows, you can make the claim (160c7):

"Every perception is true".

155 Protagoras hardly missed the opportunity to include a corresponding formulation in his book. Even if nobody really believed him, because even simple people know that there are hallucinations and errors, such a sentence was still suitable to arouse admiration in many minds, but also to cause confusion, which sophistic supporters of Protagoras did among public Presumably have taken advantage of appearances.

156A sentence would have been even more alarming if the belief in the fundamental correctness of one's own opinion (doxa) would have reinforced, namely:

"Every doxa is true".

157After this, everyone can think his opinion is correct and does not need to worry about other people's arguments. Protagoras couldn't justify such ignorance, of course. So Socrates later has him say that some opinions are "better" than others (166d-167d). In order not to saw off the branch on which he was sitting as someone who wanted to teach others, Protagoras had to relativize the relativity of truth itself again.

158152d2 With the flow theory, Socrates wants to present a "not bad speech" (cf. 151e8), that is, an opinion which he finds plausible as far as the material world is concerned, but which in the end he cannot make his own because he believes in believes the immutable being of theoretical things such as concepts and 'ideas'.

159152d2-153d7 Protagoras and the river theory. Socrates counts Protagoras among the adherents of the river theory (152e3). But in his book he only represented it, as it restrictively says, "puzzled and indistinct" and reserved it as a "secret truth" for his students (152c8-11). This truth cannot have been too secret if Socrates claims to know it. Apparently in Plato's time the opinion was widespread that Protagoras had been a decisive proponent of the flow theory, although it was not clear from his book whether and how far he had made it his own. So Socrates probably wants to say that Protagoras invoked the flow theory in his book without making the relation to his homo mensura sentence sufficiently clear.

If there is no being, but only becoming, as the radical flow theory asserts, then no even half-established knowledge would be possible. A sophist who claims to be able to teach something (e.g. how to argue in court in order to assert oneself) simply cannot tell his students that there is nothing they can learn from him. Protagoras did not believe in the possibility of reaching the ultimate truth, i.e. to achieve absolute objective knowledge, but he claimed for himself the relatively "better" knowledge that distinguishes the expert from the layman (166d-167d).

161 That Protagoras could not have been a supporter of the radical flow theory follows from the detailed form of the Homo-mensura sentence. There is talk of "things that are", i.e. the "being" of things is indeed regarded as not recognizable, but it is not in itself doubted.

According to Socrates' presentation, Protagoras appealed to the flow theory on two points. First, he used it to explain the "infinite number and variety of movements" that cause the collision of subjects and objects that lead to perceptions. Protagoras generously equated Heraclitus' flow theory and the constant movement of the universe, as it was claimed by cosmologists, in order to be able to accommodate both in his book. But that's just decoration; because to be able to claim that there are innumerable movements in everyday life, one needs neither the flow theory nor any cosmology, because everyone believes that anyway.

The other point is more delicate. According to Protagoras' theory of perception, things can have "being" but not their properties, because they only exist in "becoming" (153e2). This "becoming" is something different from the "becoming" of the flow theory. Protagoras seems to have equated both, which cannot be dismissed as merely decorative because it is factually incorrect and inadmissible. Whether Protagoras consciously or accidentally accepted this uncleanliness cannot be seen from Socrates' report, nor whether Socrates noticed it. Compare to 153d8-10.

164152d2-e1 flow theory and cosmology. Socrates presents the alleged secret doctrine: According to this, there is nothing that is "something in itself"; language deceives us with adjectives like "big" and "heavy", which designate something that can just as well be "small" and "light". Establishing expressions such as "one", "something", "somehow procured" are therefore inadmissible and one would have to replace "be" with "will" everywhere. That is the radical flow theory.

165If Socrates continues, however, to find becoming through "movement of place" (phorá), "Move" (kínesis) and "mixture" (krâsis) instead, it sounds like a cosmology like that of Empedocles, which wants to explain the origin and functioning of the existing (being) world. Socrates does not seem to distinguish between the flow theory, which denies being and only allows becoming, and a cosmology which makes arising and ceasing to be the basic principle, but does not question being. Probably that got mixed up in the contemporary debate, and Protagoras simply stuck to what was being said in his book.40

The equation of flow theory and cosmology, which is in itself quite inadmissible, is due to the ambiguity of the statement

"everything is moving"

167 to be returned.For the proponents of the flow theory it means

"there is no being, only becoming".

As a cosmological principle that makes movement the general principle of being, it has meaning

"everything that is is moved".

Only the second conception is compatible with the detailed form of the homo-mensura sentence, and only if one confuses the two meanings does a connection arise between the homo-mensura sentence and the flow theory.

One can ask who is responsible for the inadmissible equation. Did Protagoras himself make the mistake or did his students and interpreters introduce him to his teaching? Protagoras himself is probably responsible for this, who also let five be straight on this point and wanted to use both the "becoming" of the flow theory and the cosmological "movement" as an argument for the relativity of human reception. It cannot be said whether Plato and his Socrates noticed the discrepancy, because Socrates only wants to present Protagoras' teaching and is therefore not obliged to explicitly point out this weak point.

171152e1-5 The alleged exponents of the flow theory. For Socrates, supporters of the flow theory are "all those who know (sophoí) except Parmenides ". He mentions the names Protagoras, Heraclitus and Empedocles in detail. The combination and order is strange and informative at the same time. First there is Protagoras, who is at stake in the context, then Heraclitus, the father and patron saint of the theory, and finally Empedocles .

As can be seen from the (complete) Homo-mensura sentence, Protagoras cannot have been a real supporter of the flow theory. The name Empedocles is surprising because its cosmology is based on constant movement and thus also presupposes "becoming", but he does not want to abolish "being", while the flow theory denies "being" and only wants to allow "becoming". Socrates ought to know the difference, but here seems to follow a common opinion that flow theory and a cosmology based on the principle "everything is in motion" are more or less identical.

With Epicharm and Homer, Socrates passed from philosophy to poetry. Epicharm is unproblematic. He was considered the oldest comedy poet and in his (not preserved) pieces there were certainly enough places where movement and the cosmos were talked about and which could be interpreted by interested parties as poetic allusions to the flow theory.

The role assigned to Homer is based on a multilayered discussion of literary theory. Poetry then consists of comedy and tragedy; choral poetry does not count as a genre in its own right, probably because it has a place in both comedy and tragedy. The contemporary epic is simply ignored; because Homer is the epicure par excellence. There are two reasons why he is also made the inventor of tragedy poetry: the tragedians largely had their material from him, 41 and the emerging literary scholarship could not name any of the oldest regular tragedians. In Aristotle poetics (1448b38ff.) Is Homer (for whom there is also a comic epic that has not survived Margítes was attributed) even at the same time the father of comedy. For Protagoras / Socrates the old poets are generally spiritual forerunners of the later philosophers and sophists, the only difference being that they "poetically hidden" their theories, while their successors "openly expounded" them (cf. 180c8-d4).

175152e6-153a4 Homer as the ancestor of the river theory. Though Socrates in Plato Politeia Homer sees him very critically and would even like to ban him from his ideal state, he regards him as an authority who can be cited at every suitable opportunity to support your own opinion. The method of allegorical interpretation, which had already become common at the time, helps. A verse (Iliad 14,201 and 302), in which the sea deities "Okeanos" and "Tethys" are referred to as "origin and mother of the gods", is therefore equated without hesitation with the assertion "the universe arose from flow and movement". 153c10-d5 is followed by a second quotation, interpreted allegorically. Compare to 153a5-d7 (last paragraph).

Incidentally, the junction "flow and movement" implies unconsciously that Homer did not distinguish between flow theory and cosmology.

177153a5-d7 Alleged evidence for the flow theory. The characters" (semeîa), which Socrates mentions, do not speak against "being", so they do not support the flow theory, but only prove the importance of "movement" for cosmology and practical life. Whether Socrates quotes them from the book of Protagoras or enumerates arguments that were used by real Heracliteers cannot be seen from his words.

178First of all he mentions a principle: "Movement (kínesis) is the cause of supposed being and becoming, rest is that of non-being and passing away. "Flow theory and cosmology are obviously equated therein; because according to flow theory there is no" rest ", but only movement, while cosmology allows temporary or partial rest can.

179Then it continues purely cosmologically with the individual terms "the warmth", "fire", "local movement" (phorá) and "friction" (trîpsis).

Then there are examples from everyday life: living beings "arise and pass away" (i.e. are born and die), physical health is obtained through "sport", and mental health through "learning". In contrast, "calm and indolence" ruin body and soul, "calm" is a catastrophe for seafarers, supplies of food and animal feed "rot" if they are not turned from time to time.

It concludes with a quote from Homer, which is supposed to prove that Homer had already said that all life depends on the orbit of the sun. We shall gladly believe that Homer had this opinion, but from the passage quoted (Iliad 8, 18-27) it can only be read in very allegorical detours. There is only talk of a "golden rope" with which Zeus wants to compete in a tug of war against the other gods in order to prove that he is stronger than all of them combined. Moreover, this allegorical interpretation is at best suited to make Homer an unconscious cosmologist, but not a forerunner of the flow theory.

This sweeping hymn of praise to the movement sounds like a sophistic pomp which could have followed the opening Homo-mensura in Protagoras' book. For the subsequent theory of perception, it would suffice to say that perception presupposes movement because there could be no perception in an immobile cosmos.

From his point of view, Socrates cannot call the speech "not bad" because it only concerns the material being for which he can accept the flow theory. Compare to 152d2.

184153d8-154a3 A theory of perception. So far it has not been quite clear what Socrates is getting at with his detailed account. As it now turns out, it was the introduction to a theory of perception to which he is now moving.

185 He does not say who it came from, but when he comes back to it later, he speaks of the "mysteries" (156a3) of certain people, so it seems to be ascribed to the "secret truth" (152c10) that Protagoras reserved for his students. 42 But it must be in the book truth because otherwise Plato could hardly have known them exactly. It is very likely that it is Protagoras' intellectual property, that Protagoras did not take it over from someone else; because it explains why perception is fundamentally relative and thus provides a theoretical justification for the homo-mensura sentence.

This theory of perception is presented by Socrates three times43 and each time with slightly different terminology, so that the conclusion is obvious that Plato had the book of Protagoras before him and was allowing Socrates to refer to it. The repetitions and the changing terminology can hardly be explained in any other way. Socrates has a total of at least ten different expressions for the central term "contact ".44 While this can be understood as a rhetorical variation in Protagoras, it cannot be seen why Socrates or Plato should have spontaneously decided to change the terminology without motivation, especially since it makes it difficult for the reader to see through the simple mechanism of the theory.

This ingenious theory seeks to explain how one has to imagine the relationship between thing and sense organ and their interaction, which the Homo-mensura proposition asserts. This is only a conceptual representation. What specifically, i.e. physically and physiologically, goes on in perception - e.g. how the spatial distance is bridged when seeing and hearing - is a completely different question. Protagoras seems to have entered into this at most in passing in his book.45

188 According to this theory, the properties that humans perceive have no independent existence, but arise and exist only in the process of reception. They are therefore partly conditioned by the perceiving subject and are therefore subjective. Man cannot know how things are in themselves, but only perceives what arrives in his head as an image. In the form of the Homo-mensura sentence this means: "Perception is the measure of all things" .46

189 Perception comes about when the sense organ and object come into contact - directly or over a distance47. Therefore every perception presupposes movement. Theodoros and Socrates would not have seen Theätet if they had not gone to the sports field where the young people were training.

190 Protagoras must have put forward this theory several times in his book - and each time with different words; for otherwise it can hardly be explained that Socrates presents it three times without a reason of his own and each time with slightly different terminology. He comes back to this in a shorter form later (182a3-b7).

In the second, somewhat more complete version of the theory (cf. 156a3-157a2), the movements that lead to contact are not derived from flow theory, but are cosmologically justified. So there is no distinction between cosmology and flow theory. As has already been said, this inadmissible equation probably goes back to Protagoras himself, but Plato seems to have taken no offense. Otherwise he would probably not have let his Socrates go along with it in his presentation.

192 The theory works with seven terms which - partly in a modernizing way - can be called something like this:

"Subject", "Object",
"Movement", "Contact", "in between",
"Create", "Product".