The biomedical enhancement of human capacities has emerged as one of the most philosophically invigorating areas of contemporary bioethical research. In exploring the ethical dimensions of emerging biotechnologies and human–machine interfaces, the literature on human enhancement has made significant contributions to traditional problems in moral philosophy. One such area concerns the enhancement of cognitive capacities that bear on moral status. Could biotechnological or other forms of neurocognitive intervention result in the creation of ‘postpersons’ who possess a moral status that is higher than that of ‘mere persons’? If the creation of postpersons with a higher moral status is indeed possible, is it morally wrong to bring this about? Nicholas Agar takes up these two questions in his Feature Article for this issue (see page 67, Editor's Choice), in which he defends affirmative answers to both.

Most moral philosophers in the Kantian tradition would agree that were we to enhance the cognitive capacities of a non-rational sentient creature (such as a dog) so as to confer on it the psychological properties associated with personhood (such as practical rationality, self-awareness, interests that extend into the future, mutual accountability, and so on), we will have increased that creature's intrinsic moral worth relative to non-rational sentient beings, and thus we will have enhanced its moral status. Virtually all parties to the moral status enhancement debate agree on this much. Why then would it not be similarly possible in principle to enhance the cognitive capacities of mere persons so as to create postpersons who possess a higher moral status than that of mere persons? While this may seem like a reasonable extrapolation from the first scenario, it is here that moral philosophical boats begin to diverge.

Allen Buchanan was the first to address systematically the possibility of moral status enhancement1 and his work …