Lockwood on human identity and the primitive streak

Michael Lockwood has recently concluded that it can be morally permissible to perform potentially damaging non-therapeutic experiments on live human (pre) embryos. The reasons he provides in support of this conclusion commit him inter alia to the following controversial theses: (I) an organism's potentialfor twinning bears critically on the identity conditions for that organism; and (ii) functionally intact mentalitymediating neurological structures play a critical role in establishing the identity conditions for human organisms. I argue that Lockwood has given us no good reason to endorse either of these theses and, hence, that he has given us no good reason to believe that it can be morally permissible to perform potentially damaging non-therapeutic experiments on live human (pre) embryos. Michael Lockwood presents a novel variation on an increasingly popular family of arguments for the moral permissibility of performing potentially damaging non-therapeutic experiments on live human (pre)embryos.' Kindred arguments which have appeared to some philosophers to lend support to this thesis have been proposed by Mary Warnock,2 Richard McCormick,3 and Peter van Inwagen.4 The issues at stake here are much too serious to be ignored. According to Lockwood, prior to differentiation the embryo could not possibly be a determinate human being. Why not? Because Lockwood possesses a "strong intuitive inclination" that you would not have existed if "those cells, in the embryo from which you came, that in fact gave rise to the fetus, had given rise, instead, to the placenta, and vice versa[.]" But this claim is, on the face of it, quite confused. Clearly, the placenta is a part of the fetus; it is, in virtue of both its functions and its chromosomal structure, one of the fetus's organs; specifically, its prenatal organ of (among other functions) respiration, nutrition, and excretion. Given that this is so, cells which give rise to a well-formed fetus could