Aporia

A Greek term referring to a state of self-doubt; awareness of one’s ignorance. To be aware that one does not have knowledge of a certain subject.

In Plato this term is used to describe the psychological state of doubt Socrates' interlocutors find themselves in after engaging him in philosophical conversation. Socrates practices the elenctic, or cross-examination, method to test people for knowledge.

See 'Elenchus'