Let x be the fetus in my past that grew into me. Here is a valid Aristotelian argument (though Aristotle himself would probably deny (4)).
- (Premise) The identity of a bodily organ depends on the identity of the individual whose organ it is, so that if A is c's unshared heart (sharing occurs in the case of Siamese twins), and B is d's unshared heart, and c and d are distinct individuals, then A and B are distinct organs.
- (Premise) x has exactly one heart, hx, and it is unshared.
- (Premise) I have exactly one heart, hI, and it is unshared.
- (Premise) hx=hI.
- Therefore, I am x. (By 1-4)