  The third answer parallels the response we would give in the case of bodies. But as an account of the subjective situation, it is arguable that this makes no sense. Call the creature that would have emerged from the slightly modified sperm, ‘Jones2’. Is the overlap suggestion that, just as, say 85% of Jones2’s original body would have been identical with Jones’, about 85% of his psychic life would have been Jones’? That it would have been like  Jones’ – indeed that Jones2 might have had a psychic life 100% like  Jones’ – makes perfect sense, but that he might have been to that degree, the same psyche – that Jones ‘85% existed’  – arguably makes no sense. Take the case in which Jones and Jones2 have exactly similar lives throughout: which 85% of the 100% similar mental events do they share? Nor does it make sense to suggest that Jones might have participated in the whole of Jones2’s psychic life, but in a rather ghostly only 85% there manner. Clearly, the notion of overlap of numerically identical psychic parts cannot be applied in the way that overlap of actual bodily part constitution quite unproblematically can.