Socrates and Meno are discussing what virtue is and whether it can be taught in Plato’s dialogue Meno. This dialogue offers a good impression of the Socratic dialectical style. In it Socrates rephrases something that Meno has said in the form of a paradox. Here’s an excerpt:
MENO: How will you look for it, Socrates, when you do not know at all what it is? How will you aim to search for something you do not know at all? If you should meet with it, how will you know that this is the thing that you did not know?
SOCRATES: I know what you want to say, Meno. Do you realize what a debater’s argument you are bringing up, that a man cannot search either for what he knows or for what he does not know? He cannot search for what he knows—since he knows it, there is no need to search—nor for what he does not know, for he does not know what to look for.
(Plato: Complete Works; Edited by John M. Cooper and D. S. Hutchinson; “Meno,” translated by G.M.A. Grube; Page 880)If you know what you are looking for, there is no need for an inquiry; if you don't know what you are looking for, then an inquiry is impossible—this is essentially a sophistical argument; it is possible for someone to know the question and not have an answer. But Socrates takes the argument seriously and goes on to propose his famous doctrine of recollection.