Rodger et al 1 argue that ‘ethically defensible xenotransplantation should entail the use of genetic disenhancement if it is demonstrated that’ the pain and suffering of donor pigs ‘cannot be eliminated by other means’. The phrase ‘genetic disenhancement’ refers to genetic manipulation that would produce an animal that is either less able or entirely unable to experience pain and suffering. (The phrase is euphemistic because, on one possible reading, it suggests the removal of an existing enhancement, rather than what it actually is, namely a diminishment relative to the species norm.)

The authors acknowledge that genetic ‘disenhancement’ is not a ‘morally ideal ‘solution’, but argue that ‘it is morally better to prevent unavoidable pain until a viable non-animal alternative becomes available’ (p. 1).

In advancing this argument, they explicitly state that they make no assumption that xenotransplantation is, in principle, morally permissible. They take no stand on that issue, which is beyond the scope of their paper. They assume only that ‘ (1) xenotransplantation research will inevitably continue and (2) causing pain and suffering requires sufficient justification’ (p. 1).

However, in the absence of an assumption that xenotransplantation is, in principle, morally permissible, the authors have not established their …