Meno’s Paradox

Thesis: It is impossible to find the answer to the question ‘What is F?’ (‘the question about the nature of F’); that is to say, rational inquiry into the nature of things is impossible.

Proof: One either knows the answer or he does not. (‘The dilemma’) But if one already knows the answer, then he cannot find it, since he already has it. So in this case the question is pointless. On the other hand, if one does not know the answer, then he has no idea of what an F is, and so he would not recognize the right answer even if he stumbled on it. (If you have no idea of what a chiliagon is, then you don’t know whether ‘a polygon of one thousand angles’ or ‘a polygon of one thousand and one angles’ is the right answer’.) So, in either case, the inquiry into the nature of F is impossible.

Socrates’ reply

Meno’s dilemma is false. In most cases, the nature of F is not fully known, but it is not totally unknown either. We have a certain latent, implicit knowledge of the nature of things, which can be made explicit in the process of rational inquiry, the process of dialectical questioning. The slave boy did not explicitly know the answer to the question ‘What is the length of the side of a square double in area of a given square?’, but he was able to recognize the wrong answers as such, and eventually the right answer as such. For this recognition he did not use his senses, any previous teaching, or Socrates’ suggestions, indeed, apparently any information he could have gained in this life. Therefore, Socrates proposes

Socrates’ thesis concerning the origin of a priori knowledge

A priori knowledge is prenatal (from before birth).

This thesis entails

Socrates’ conclusion concerning the nature of the human soul

The soul of a human being exists before his or her birth.