  Why is this so? Imagine the case where we are not sure whether it would have been Jones’ body – and, hence, Jones – that would have been created by the slightly modified sperm and the same egg. Can we say, as we would for an object with no consciousness, that the story something the same, something different is the whole story: that overlap of constitution is all there is to it? For the Jones body as such, this approach would do as well as for any other physical object. But suppose Jones, in reflective mood, asks himself ‘if that had happened, would I have existed?’ There are at least three answers he might give to himself. (i) I either would or would not, but I cannot tell. (ii) There is no fact of the matter whether I would or would not have existed: it is just a mis-posed question. (iii) In some ways, or to some degree, I would have, and in some ways, or to some degree, I would not. The creature who would have existed would have had a kind of overlap of psychic constitution with me.