 Determinism is a highly general claim about the universe: very roughly, that everything that happens, including everything you choose and do, is determined by facts about the past together with the laws. Determinism isn’t part of common sense, and it is not easy to take seriously the thought that it might, for all we know, be true. The incompatibilist believes that if determinism turned out to be true, our belief that we have free will would be false. The compatibilist denies that the truth of determinism would have this drastic consequence. According to the compatibilist, the truth of determinism is compatible with the truth of our belief that we have free will. The philosophical problem of free will and determinism is the problem of deciding who is right: the compatibilist or the incompatibilist.