How should we treat human–pig chimeras, non-chimeric pigs and other beings of uncertain moral status?

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 (and/or other kinds of chimeric animals). 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 (or near 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 (or require greater support) in the context of meat production than human–animal chimera research. We do not think the social consensus in favour …