What do people remember about the teachers they loved? Their passion, their inspiration--and their conviction. In this talk, Enda Duffy examines how in humanities teaching in particular the truth is often held to be provisional and undecidable. Yet this ambivalence undermines passionate thinking. It forbids us as teachers from transmitting the most vital part: courage. The best teaching happens when teachers challenge their students to see what the truth is and then to stand up for it.