Our recent article begins by describing a new technique for creating human–animal chimeras. This technique—known as interspecies blastocyst complementation—may enable us to generate human organs inside of human–pig chimeras. One central concern about farming human–pig chimeras for their organs is that their moral status would be uncertain and potentially significant. Our article is partly, but not only, about such concerns. At the heart of our paper are two broader questions. First, how should we treat beings of uncertain moral status? And (...) second, do our reasons for thinking that human–pig chimeras have uncertain moral status also provide reason to think regular, non-chimeric pigs have uncertain moral status? We thank Mike King, Christian Munthe, David Resnik, Per Sandin and Rob Streiffer for their commentaries on our paper, each of which serves to clarify the ethical issues at play. In this response, we want to respond to one criticism, acknowledge the force of several others, and point towards some philosophical work that remains to be done. First, the criticism. Resnik questions the parallel we draw between human–pig chimeras and regular pigs. In the case of regular pigs, there is currently a social consensus that it is morally acceptable to farm pigs for food. For Resnik, this consensus imposes a special burden on those who wish to argue against it; ‘one needs substantial evidence that the majority view is wrong’.1 Since an equivalent consensus does not exist in relation to human–pig chimeras, one might think that moral uncertainty concerns have less force in the context of meat production than human–animal chimera research. We do not think the social consensus in favour …. (shrink)

Although in certain contexts judged to be over-rated,1 consistency is generally held to be a virtue in arguments about medical ethics. In everyday life, to be told that you are acting hypocritically, in a manner that is inconsistent with values you profess, is at least embarrassing, and depending on the circumstances can have more serious consequences, not least for politicians. How far complete consistency in thought and action is humanly possible or even desirable is a more doubtful however. In terms (...) of inconsistency over time, certainly, the maxim ‘When the facts change, I change my mind’ can be a reasonable defence: but in order to avoid less defensible forms of inconsistency, changing your mind about one thing may require changing it about others also. To take seriously just such a possibility is the ethical challenge of this month’s feature article: ‘Moral Uncertainty and the Farming of Human-Pig Chimeras’ by Julian Koplin and Dominic Wilkinson.2 In this case, the facts that have or could soon have changed surround the emerging possibility of generating, within human-pig chimeras, human organs for transplantation into patients who need them and of avoiding the need for immunosuppression by generating the organs using stem cells from the patients themselves. The potential benefits of this possible answer to the worldwide shortage of transplantable organs clearly are immense. But, Koplin and Wilkinson point out, there are also serious potential harms. If human-pig chimeras with ‘partly humanised brains’ were to ‘develop morally relevant cognitive capacities’, such as dawning self-awareness, their moral status would make farming and killing them ‘a serious moral wrong’. Yet having said that, the real difficulty is that we cannot be certain, philosophically, ‘precisely what capacities confer what …. (shrink)