"What we are seeing," said Dr. Gail Zellman, a RAND Corporation researcher in Santa Monica, California, "is that there is reluctance by parents to do anything other than hold them."1 The reference to "holding" was not to any reluctance of parents to hold newborn children in their arms, but to holding in cold storage spare embryos created through in vitro fertilization procedures. Recent surveys have indicated that there are at least 396,526 frozen human embryos in the United States, with more being created daily.2 Many parents experience deep ambivalence, wishing neither to implant these nascent human beings in the womb nor to destroy them. These frozen human embryos, existing in a limbo of suspended animation, are a powerful symbol and reminder of the deep ambivalence felt by the culture at large concerning the moral status of the human embryo.
In his influential book, When Did I Begin?, Norman Ford argued for a fundamental distinction between "potential" human individuality and "actual" human individuality. According to Ford, while genetic individuality begins at fertilization, "ontological" or fully actual human individuality is not established until some time after the fourteenth day following fertilization, since prior to that time, the nascent human entity is capable of splitting or "twinning," leading to the birth of identical (monozygotic) twins.3 Such arguments from the possibility of human "twinning" have been appealed to by others as a basis for public policies allowing experimentation on human embryos prior to day fourteen, it being presumed that no true, distinct human being yet exists.4
It is the purpose of this article to argue that Ford's understanding of human individuality and his argument from twinning is based on an unwarranted and questionable assumption: namely, that indivisibility is a necessary property of true human individuality. First, the historical and social location of this ethical debate will be briefly reviewed; second, Ford's argument and distinctions will be rehearsed; and third, several arguments and thought experiments, including one based on John Rawls' concept of the "original position"5 will be advanced, with the purpose of demonstrating the problematic nature of Ford's assumption.
II. The Social and Historical Location of the Debate
The controversy concerning the moral status of the human embryo in the United States can be situated within a context created by four major social and biomedical developments in the last quarter century: abortion, in vitro fertilization, cloning, and embryonic stem cell research. The United States Supreme Court decision in 1973, Roe v. Wade, ignited an ongoing controversy over abortion that has pitted the defenders of a woman's "right to choose" against the defenders of the unborn's "right to life."6 The birth of baby Louise Brown in England in 1978 heralded the spread of in vitro fertilization technology first in England, then in the United States, Australia, and other countries. This new technology also posed the issue of the moral status of human embryos created in vitro but cryopreserved rather than implanted in the womb.7 In 1994 a panel of experts convened by the National Institutes of Health recommended that research on pre-implantation human embryos should be permitted,8 but public opposition led to a ban on federal funding for such experimentation. The announcement in 1997 that Ian Wilmut, a Scottish scientist, had successfully cloned a sheep, "Dolly," generated a burst of media coverage and widespread concern about the possible dangers of human cloning. The cloning controversy was subsequently complicated by the related controversy concerning the experimental use of human embryonic stem cells, derived from the early embryo. The Clinton administration instituted a ban on federal funding of human reproductive cloning in 1998, and in 2001 the Bush administration issued guidelines restricting …