‘Your qualms about embryonic stem-cell research are similarly obscene. Here are the facts: stem-cell research is one of the most promising developments in the last century of medicine. It could offer therapeutic break-throughs for every disease or injury process that human beings suffer—for the simple reason that embryonic stem cells can become any tissue in the human body. This research may also be essential for our understanding of cancer, along with a wide variety of developmental disorders. Given these facts, it is almost impossible to exaggerate the promise of stem-cell research. It is true, of course, that research on embryonic stem cells entails the destruction of three-day-old human embryos. This is what worries you.
Let us look at the details. A three-day-old human embryo is a collection of 150 cells called a blastocyst. There are, for the sake of comparison, more than 100,000 cells in the brain of a fly. The human embryos that are destroyed in stem-cell research do not have brains, or even neurons. Consequently, there is no reason to believe they can suffer their destruction in any way at all. It is worth remembering, in this context, that when a person’s brain has died, we currently deem it acceptable to harvest his organs (provided he has donated them for this purpose) and bury him in the ground. If it is acceptable to treat a person whose brain has died as something less than a human being, it should be acceptable to treat a blastocyst as such. If you are concerned about suffering in this universe, killing a fly should present you with greater moral difficulties than killing a human blastocyst.
Perhaps you think that the crucial difference between a fly and a human blastocyst is to be found in the latter’s potential to become a fully developed human being. But almost every cell in your body is a potential human being, given our recent advances in genetic engineering. Every time you scratch your nose, you have committed a Holocaust of potential human beings. This is a fact. The argument from a cell’s potential gets you absolutely nowhere.
But let us assume, for the moment, that every three-day-old human embryo has a soul worthy of our moral concern. Embryos at this stage occasionally split, becoming separate people (identical twins). Is this a case of one soul splitting into two? Two embryos sometimes fuse into a single individual, called a chimera. You or someone you know may have developed in this way. No doubt theologians are struggling even now to determine what becomes of the extra human soul in such a case.
Isn’t it time we admitted that this arithmetic of souls does not make any sense? The naive idea of souls in a Petri dish is intellectually indefensible. It is also morally indefensible, given that it now stands in the way of some of the most promising research in the history of medicine. Your beliefs about the human soul are, at this very moment, prolonging the scarcely endurable misery of tens of millions of human beings.
You believe that “life starts at the moment of conception.” You believe that there are souls in each of these blastocysts and that the interests of one soul—the soul of a little girl with burns over 75 percent of her body, say—cannot trump the interests of another soul, even if that soul happens to live inside a Petri dish. Given the accommodations we have made to faith-based irrationality in our public discourse, it is often suggested, even by advocates of stem-cell research, that your position on this matter has some degree of moral legitimacy. It does not. Your resistance to embryonic stem-cell research is, at best, uninformed. There is, in fact, no moral reason for our federal government’s unwillingness to fund this work. We should throw immense resources into stem-cell research, and we should do so immediately. Because of what Christians like yourself believe about souls, we are not doing this. In fact, several states have made such work illegal. If one experiments on a blastocyst in South Dakota, for instance, one risks spending years in prison.
The moral truth here is obvious: anyone who feels that the interests of a blastocyst just might supersede the interests of a child with a spinal cord injury has had his moral sense blinded by religious metaphysics. The link between religion and “morality”—so regularly proclaimed and so seldom demonstrated—is fully belied here, as it is wherever religious dogma supersedes moral reasoning and genuine compassion.’
– Harris. S. 2006. Letter To A Christian Nation p. 11-12