Full Idea
Why isn't certainty required for knowledge? Because we are often prepared to allow that someone does in fact have knowledge when the person is so uncertain they would not claim knowledge for themselves (the 'diffident schoolboy').
Gist of Idea
A pupil who lacks confidence may clearly know something but not be certain of it
Source
Jonathan Dancy (Intro to Contemporary Epistemology [1985], 2.1)
Book Reference
Dancy,Jonathan: 'Introduction to Contemporary Epistemology' [Blackwell 1985], p.24