Abstract: For any x there can be nothing y such that there is no fact that x = y and at the same time no fact that x ( y. For if there were, then y would differ from x in this respect: that there is no fact that x is it and no fact that x is not it. In this case there is a fact that x ( y. In short, identity is always determinate. This argument is defended at length against the most developed response to date, that of Terence Parsons. The proof is also contrasted with a similar proof due to Gareth Evans.

Keywords: determinacy, Evans, identity, Leibniz, Parsons,