 It is notable that much of the same reasoning that theists employ in the Kalaam cosmological argument for the existence of God may be used for the universe itself. If we inquire into the origin of the universe, it may be suggested (1) that it simply began without reason, (2) that it was somehow self-creating, or (3) that its origin requires a prior cause which in turn calls for an infinite causal chain. Each of these answers has sufficient problems such that one might well prefer to argue instead, (4) that the universe in fact exists necessarily.