Derek Parfit famously opined that causing a person to exist with a life barely worth living can be wrong, although it is not wrong for that person. This conundrum is known as the nonidentity problem. Parfit also held that persons can, in a morally relevant sense, be caused to exist in the distant future by actions that make the agent a necessary condition for a person’s existence. When these views are combined, which he did, and applied explicitly to persons with a life not worth living, which he did not, an interesting conditional conclusion can be drawn. If every family line eventually produces a person with a life not worth living, and if causing that person to exist cannot be justified by the benefits befalling others in the family line, it is always wrong to have children. Parfit did not draw this antinatalist conclusion, but an analysis of his introduction of the nonidentity problem shows that he could have. Since Parfit’s other views on population ethics continue to be discussed with relative respect, it stands to reason that the antinatalist position should be no exception. Right or wrong, it has its legitimate place in considerations concerning the future of reproduction.

I argue that, given certain prominent views of personal identity and prudence, the nonidentity problem, or a very similar problem, can arise postconception. I clarify and defend this claim by considering the implications of these views for prenatal injury.

This paper considers two objections based in axiological considerations against the position that whether a given outcome, or possible future or world, is morally worse than a second world may depend in part on what is going on at a third world. Such a wide-angled approach to determining worseness is critical to the solution I have previously proposed in connection with the nonidentity problem. I argue that both objections fail.

This paper provides an analysis of the statement, made in many papers and reports on the use of gene editing in humans, that we should only use the technology when it is safe. It provides an analysis of what the statement means in the context of nonreproductive and reproductive gene editing and argues that the statement is inconsistent with the philosophical commitments of some of the authors, who put it forward in relation to reproductive uses of gene editing, specifically their commitment to Parfitian nonidentity considerations and to a legal principle of reproductive liberty.

But, if that is true it raises a question about why the statement is made. What is its discursive and rhetorical function? Five functions are suggested, some of which are more contentious and problematic than others. It is argued that it is possible, perhaps even likely, that the “only when it is safe” rider is part of a deliberate obfuscation aimed at hiding the full implications of the arguments made about the ethics of gene editing and their underlying philosophical justifications.