The argument which Coburn criticises runs like this. Suppose a person A to undergo a sudden change, and to acquire a character exactly like that of some person known to have lived in the past, B. Suppose him further to make sincere memory claims which entirely fit the life of B. We might think these conditions sufficient for us to identify A (as he now is) with B. But they are not. For another contemporary person, C, might undergo an exactly similar change at the same time as A, and if the conditions were sufficient to say that A = B, they would be sufficient to say that C = B as well. But it cannot be the case both that A = B and C = B, for, were it so, it would follow that A = C, which is absurd. One can avoid this absurdity by abandoning one or both of the assertions A = B and C = B.