In fact this does not follow: we could simply deny that Dh and -Di have causes. For since to say that all causation is deterministic is not to say that all contingent facts have causes, we can easily reconcile causal determinism with natural radioactive decay by denying that it has any causes at all. But determinism is not so easily reconciled with what I shall call forced decay. Suppose that at to we bombard the nucleus of our E atom h (Bh) with a subatomic particle. If h were in its normal state its chance of decaying by to+ 1, ch(Dh), would be 'A, which we may take to be minute: say 10-10. But bombarding h makes it almost certain to decay by to+l, i.e. raises ch(Dh) to a value, 'A', very close to 1: say to 1-10-10. Suppose now that h does decay by to+ 1. In these circumstances did it not do so because it was bombarded: is not 'Dh because Bh' true?