Imagine that there is a button that, if pushed, will cause all sentient life to painlessly cease to suffer forever. […] Would there be no obligation to press the button?

I once devised a test question which I put to many people to discover whether they were pessimists. The question was: ‘If you had the power to destroy the world, would you do so?’ I put the question to [Bob Trevelyan] in the presence of his wife and child, and he replied: ‘What? Destroy my library?—Never!’