   Suppose, optimistically, that there never will be a nuclear holocaust. Then, for every \(\mathsf{B\land H}\)-world, there will be a more similar \(\mathsf{B\land\neg H}\)-world, one where a small difference prevents the holocaust, such as a malfunction in the electrical detonation system. In short, a world where Nixon presses the button and a malfunction prevents a nuclear holocaust is more like our own than one where there is a nuclear holocaust that changes the face of the planet. But then Lewis’ (1973b: 92) Proposal incorrectly predicts that (41) is false.