gathers clear examples of a virtue and then seeks to establish what they had in common. According to Guthrie, Socrates lived in an era when sophists had challenged the meaning of various virtues, questioning their substance; Socrates's quest for a definition was an attempt to clear the atmosphere from their radical skepticism. Some scholars have argued that Socrates does not endorse the priority of definition as a principle, because they have identified cases where he does not do so. Some have argued that this priority of definition comes from Plato rather than Socrates. Philosopher Peter Geach, accepting that Socrates endorses the priority of definition, finds the technique fallacious. Αccording to Geach, one may know a proposition even if one cannot define the terms in which the proposition is stated. Socratic ignorance Plato's Socrates often claims that he is aware of his own lack of knowledge, especially when discussing ethical concepts such as arete (i.e., goodness, courage) since he does not know the nature of such concepts. For example, during his trial, with his life at stake, Socrates says: "I thought Evenus a happy man, if he really possesses this art (technē), and teaches for so moderate a fee. Certainly I would pride and preen myself if I knew (epistamai) these things, but I do not know (epistamai) them, gentlemen". In some of Plato's dialogues, Socrates appears to credit himself with some knowledge, and can even seem strongly opinionated for a man who professes his own ignorance. There are varying explanations of the Socratic inconsistency (other than that Socrates is simply being inconsistent). One explanation is that Socrates is being either ironic or modest for pedagogical purposes: he aims to let his interlocutor to think for himself rather than guide him to a prefixed answer to his philosophical questions. Another explanation is that Socrates holds different interpretations of the meaning of "knowledge". Knowledge, for him, might mean systematic understanding of an ethical subject, on which Socrates firmly rejects any kind of mastery; or might refer to lower-level cognition, which Socrates may accept that he possesses. In any case, there is consensus that Socrates accepts that acknowledging one's lack of knowledge is the first step towards wisdom. Socrates is known for disavowing knowledge, a claim encapsulated in the saying "I know that I know nothing". This is often attributed to Socrates on the basis of a statement in Plato's Apology, though the