The problem I want to talk to you about tonight is the problem of belief. What does it mean to believe? We use this word all the time, and I think behind it lurk some really extraordinary taboos and confusions. What I want to argue tonight is that how we talk about belief- how we fail to criticize or criticize the beliefs of others, has more importance to us personally, more consequence to us personally and to civilization than perhaps anything else that is in our power to influence.