In the twentieth century answers are usually cast in terms of social, psychological or biological functions; in other words, humour is seen as part of our collective adaptation to our situation. But in the past speculation was by no means so limited: as we have seen, the medieval Church was much exercised by this question, in the sense that when it confronted the contradictory evidence of the Bible and Aristotle on the question of whether laughter was one of the defining characteristics of humanity it was essentially trying to decide what the purpose of laughter was.1