NICHOLAS HUMPHREY is School Professor at the Centre for Philosophy of Natural and Social Science at the London School of Economics. He is the author, most recently, of Seeing Red: A Study in Consciousness.
Bertrand Russell’s idea, put forward eighty years ago in his Sceptical Essays, is about as dangerous as they come. I don’t think I can better it: “I wish to propose for the reader’s favourable consideration a doctrine which may, I fear, appear wildly paradoxical and subversive. The doctrine in question is this: that it is undesirable to believe in a proposition when there is no ground whatever for supposing it true.”