Theaetetus (dialogue)

The Theaetetus (Greek Θεαίτητος, Germanized also Theaetetus or Theaetetus ) is a dialogue of the philosopher Plato. He is one of the mid to later works and, together with the dialogue Cratylus, Sophist and the Statesman to the second tetralogy of Plato's works. In addition to Socrates occur therein Theodoros of Cyrene, and the eponymous Theaetetus. The dialogue discussed three different concepts of knowledge, without finding a definitive answer.


The main part of the dialogue portrays a fictional conversation that Socrates has with the young Theaetetus and Theodorus, his mathematics teacher, out. Right at the beginning Socrates, the central question of the entire interview: What is knowledge? Theaetetus first responds with a list of different types of knowledge; However, Socrates would amount to a general definition. Theaetetus this kind of generality, from the mathematics involved are already known, but he is unsure if he can ' meet Socrates claims. Then Socrates describes his philosophical activity by the famous comparison with that of his mother, the midwife was ( after the Greek word for the art of midwifery, Socrates ' method is also called maieutics ). As a midwife can help women in childbirth through control of the birth process, so please help Socrates someone who is pregnant go with a thought to bring this idea to the world. His main task, however, was to examine the thoughts of births to see if they really are any good or mere appearance births.

Theaetetus then prepared to face up to this process, and proposes a first definition of knowledge before: knowledge is perception. Socrates takes up this proposal by bringing him with a thesis of the philosopher Protagoras in conjunction, namely that man is " the measure of all things, of beings that they are, the non-being that they are not". This thesis is hereinafter supplemented by another, which is associated later Heraclitus, that there is nothing, but everything going. After the presentation of this triplet of theses followed by a detailed critical analysis, in which both on the practical consequences, such as for teaching practice, as well as by the internal consistency of these theses is asked. The test ends with the devastating result that someone who is seriously represent these theses could neither convince others speak at all meaningful. Because actually the theories of Protagoras and Heraclitus but are not equivalent first proposed definition with Theätets, it remains unclear whether this is also refuted. Therefore, it is followed by a re-examination of, but now under the premise that under physiological perception of the process of perception is to be understood and not the result of ( a emerged from the perceiving mind). From this perspective, knowledge can not exist in the perception because knowledge must be a judgment always, occurs in at least the "to be" as the copula.

Theaetetus sees his first definition proposal is therefore considered to have failed and proposes a second definition: Knowledge is true opinion. Socrates responds to this proposal first with a digression: he has always want to know what is actually a false opinion - and he discussed with Theaetetus in detail about this problem. A total of five proposals to explain the false opinion are discussed, none of them appears to be successful (however deceptive that mediated by Socrates impression, because the last two proposals, which are known under the name " wax block model " and " pigeon model," have other viable approaches on ). After this digression the conversation to Theätets second proposed definition returns, and Socrates shows that it is not sufficient that an opinion is true, to be considered knowledge as one can come to random and therefore unreliable way to true opinions - in such cases but can hardly be considered the opinion of knowledge, for in the same way you might as well come to a wrong opinion.

Theaetetus is now bringing yet a third definition: knowledge is true opinion with explanation ( in Greek stands for " statement " the word logos). Once again Socrates first again applying an unusual and surprising interpretation of the definition, which turns out to be untenable, the end of the conversation is the distinction between three meanings of logos and examining whether from these meanings gives each a useful definition of knowledge. The judgment of the caller, this is not the case, so that the conversation ends without a definitive answer.

Philosophical significance

In the research of the 20th century was for a long time a question to the fore: How has the Theaetetus of Plato's theory of ideas behaves. On the one hand the Theaetetus probably originated in the same period or after the dialogues in which Plato introduces the so-called doctrine of ideas (eg, the Politeia ); and an assertion of the doctrine of ideas is that there can be knowledge only of the ideas. But to be in the Theaetetus, in spite of its subject, the ideas no mention. Does Plato 's theory of ideas so here is the abandoned? Or is the conversation that is why no result, because the ideas are not taken into account? The first variant was represented recently by David Bostock (1988 ), the second by David Sedley ( 2004).

In recent decades, the Theaetetus has been read but more and more as a very rich contribution to the theory of knowledge itself: the three proposed definitions are with today's common theories of knowledge closely related, it addressed a number of problems, even today determine the Discussion - eg whether perception is sufficient as a causal relation to the world, to make a review of knowledge, or the problem of the reliability of the sources of knowledge, or whether you do not get into an infinite regress, if the justification for a necessary condition of knowledge is power ( see in particular the comments made by McDowell (1973) and Burnyeat (1990)).

For the understanding of the dialogue as a whole is crucial how one assesses the failure of the various investigations and the internal context of the issues raised (see Heitsch (1988)). It could be that like a red thread through the entire conversation passeth through the problem that knowledge on the one hand always be result of an autonomous cognitive activity due to its ruling structure needs and therefore can never be directly reduced to a causal relationship between the knower and the world, on the other hand this autonomous cognitive activity but also the source of false opinions is. An adequate answer to the question what knowledge has to clarify accordingly, as the judging cognitive activity can reliably lead to true judgments (see Becker ( 2007) ).

Editions and translations

  • Otto Apelt (translator ): Plato: Theaetetus. In: Otto Apelt (ed.): Plato: All dialogs, Vol 4, Meiner, Hamburg 2004, ISBN 3-7873-1156-4 ( translation with introduction and explanatory notes; reprint of the 4th edition, Leipzig 1923)
  • Friedrich Schleiermacher (translator ): Theaetetus. In: Erich Loewenthal (ed.): Plato: Complete Works in three volumes, Vol 2, unchanged reprint of the eighth, looked through edition, University Press, Darmstadt 2004, ISBN 3-534-17918-8, pp. 561-661 ( translation only )