One response to Derek Parfit's 'mere addition paradox' invokes the relation of 'parity'. Since parity is a form of 'incommensurateness' in John Broome's terms, three doubts which Broome raises about accounts involving incommensurateness in Weighing Lives pose a challenge for this response. I discuss two of these. They emerge from a discussion of various intuitions about 'neutrality'. I argue that an account based on parity may be no less consistent with Broome's intuitions than is his own vagueness view.