This paper critically examines the biology of species identity and the morality of crossing species boundaries in the context of emerging research that involves combining human and nonhuman animals at the genetic or cellular level. We begin with the notion of species identity, particularly focusing on the ostensible fixity of species boundaries, and we explore the general biological and philosophical problem of defining species. Against this backdrop, we survey and criticize earlier attempts to forbid crossing species boundaries in the creation (...) of novel beings. We do not attempt to establish the immorality of crossing species boundaries, but we conclude with some thoughts about such crossings, alluding to the notion of moral confusion regarding social and ethical obligations to novel interspecies beings. (shrink)

Singer and Dawson point out that two arguments against abortion, that the embryo is entitled to protection because from fertilization it is (1) a human being or (2) a potential human being, are also used by opponents of embryo experimentation. They focus on the second argument, evaluating the notion of potentiality as it applies to gametes, to the unimplanted embryo, to the implanted developing embryo, and to the embryo created by in vitro fertilization (IVF). They argue that there is a (...) crucial distinction between natural reproduction, in which all that is needed for the embryo to have a prospect of reaching its potential is for those involved to refrain from stopping it, and IVF, in which the embryo cannot develop into a person without a deliberate human act. Reproductive techniques necessitate our rethinking of established views about potentiality, and how it should be applied to the embryo in a laboratory. (KIE abstract). (shrink)

Human–nonhuman chimeras have been the focus of ethical controversies for more than a decade, yet some related issues remain unaddressed. For example, little has been said about the relationship between the origin of transferred cells and the morally relevant capacities to which they may give rise. Consider, for example, a developing mouse fetus that receives a brain stem cell transplant from a human and another that receives a brain stem cell transplant from a dolphin. If both chimeras acquire morally relevant (...) capacities as a result of transplantation, and if those capacities are indistinguishable, should the difference in cell origin matter to how we classify these creatures? I argue that if morally relevant capacities are easy to detect, cell origin is irrelevant to how the chimera ought to be treated. However, if such capacities are hard to detect, cell origin should play a role in considerations about how to treat the chimera. (shrink)

Debates on the moral status of human embryos have been highly and continuously controversial. For many, these controversies have turned into a fruitless scholastical endeavor. However, recent developments and insights in cellular biology have cast further doubt on one of the core points of dissent: the argument from potentiality. In this article we want to show in a nonscholastical way why this argument cannot possibly survive. Getting once more into the intricacies of status debates is a must in our eyes. (...) Not merely intellectual coherence but the standing and self-understanding of current stem cell research might profit from finally taking leave of the argument from potentiality. (shrink)