In philosophy, the nonidentity problem has become the leading paradigm. In the succession of paradigms, as described by Thomas S. Kuhn, it is the "normal science" of today. In this anthology, virtually none of the articles explicitly labels the nonidentity problem as esoteric, far-fetched, or generally outlandish. What a pity. It would have benefited from such a radically sceptical view.
The nonidentity problem, if it were relevant, would be of utmost importance for moral judgements in areas such as climate change or reparations, and philosophers have remarked on that. Why is it, then, that outside philosophy there is no talk about the nonidentity problem at all? [...] Are non-philosphers [sic] just too dumb to recognize the problem or are Roberts and Wassermann misled when they claim that the problem is broad and deep?
After this false dichotomy, the reviewers (Jörg Chet Tremmel and Ned Chambers) go on to describe their two "objections" to taking the non-identity problem seriously. The first is reincarnation:
Nonidentity claims presuppose that humans are not reborn. But if we adopt the reincarnation view, the nonidentity paradigm is no longer applicable. Then, the disabled child could very well reproach its parents for having harmed it, because the same person might have been born with a healthy body if it had been born one year later.
Anything's possible, right?
Their second objection rests on a simple misunderstanding of the non-identity problem:
The nonidentity thesis can be rephrased as follows: "Because of an action by a present agent, a future individual came into existence. This action cannot have harmed this person since without it, she would never have existed."
The 'butterfly effect' argument takes issue with the 'because'. The question of which egg and sperm fuse depends on countless actions, so it is misleading to pick out only one that is detrimental to a future person and hold it responsible for the conception and birth of a child.
This is just confused. The non-identity argument does not rely on picking out a factor as solely responsible, or "the" cause, of a particular person's conception. What matters is the mere counterfactual: that if the one thing had been done differently, then this child would not have existed. This is obviously compatible with acknowledging a whole raft of similar counterfactuals, and so it in no way implies that the identified factor is uniquely responsible for the conception.