 It might be hoped that we could give a full account of permissible procreation by appealing only to the interests of the individuals affected by procreative decisions. Unfortunately, there is reason to think that this may not be possible. Consider the following sort of case, introduced into the literature by Parfit (1984), and known as the non-identity problem (Hanser 1990; Harman 2004; Woodward 1986; entry on  the nonidentity problem):