Nonidentity problem

Savulescu coined the phrase procreative beneficence. It is the controversial^{[4][5][vague]} moral obligation, rather than mere permission, of parents in a position to select their children, for instance through preimplantation genetic diagnosis (PGD) and subsequent embryo selection or selective termination, to favor those expected to have the best possible life.^[6][7][8]

An argument^[vague] in favor of this principle is that traits (such as empathy, memory, etc.) are "all-purpose means" in the sense of being instrumental in realizing whatever life plans the child may come to have.^[9]

Philosopher Walter Veit has argued that because there is no intrinsic moral difference between "creating" and "choosing" a life, eugenics becomes a natural consequence of procreative beneficence.^[4] Similar positions were also taken by John Harris, Robert Ranisch and Ben Saunders respectively.^[10][11][12]

Bioethicist Rebecca Bennett criticises Savulescu's argument. Bennett argues that "the chances of any particular individual being born is spectacularly unlikely, given the infinite number of variables that had to be in place for this to happen. In order for any particular individual to exist, that individual's parents have to have been created in the first place, they have to meet at the right time and conceive us at a particular time to enable that particular sperm to fuse with that particular egg. Thus, it is clear that all sorts of things, any change in society, will effect who is born." According to Bennett, this means that no-one is actually harmed if one does not select the best offspring, as the individuals born could not have had any other, worse life as they would otherwise never have been born – "choosing worthwhile but impaired lives harms no-one and is thus not less preferable", as Bennett puts it. Bennett argues that while advocates of procreative beneficence could appeal to impersonal harm, which is where one should aim to ensure the maximum possible potential quality of life and thus embryos without or with the least impairments should be selected (as the impersonal total quality of life will be improved), this argument is flawed on two counts. Firstly on an intuitive level, Bennett questions if benefit or harm that does not affect anyone (i.e. it is impersonal) should be worthy of consideration as no actual people will gain or lose anything. Secondly and on a theoretical level, Bennett argues that attempting to increase the sum total impersonal happiness (or decrease impersonal harm) can lead to repugnant conclusions, such as being obliged to produce as many offspring as possible to bring more people into the world to raise the level of impersonal happiness, even if the quality of life of individuals suffers for it due to scarcity and overcrowding. Bennett argues that this conclusion is repugnant because "it cares little about what we normally regard as morally important: the welfare of individual people".^[13]