Philosophers from the Middle Ages used to debate questions like: How many angels can fit on the tip of a pin? They also entertained dilemmas such as: At what point during a pregnancy is the immortal soul infused with its temporal body? The latter question posed no shortage paradoxes. For instance, would the soul of a fetus that died before birth make it to heaven? After all, church doctrine held that baptism was a prerequisite entering the pearly gates.
Serious Christian philosophers, such as Thomas Aquinas, believed that each individual souls was created by God, but that it was only some months after conception that the material body of the fetus was developed enough to be co joined with the soul. Many would take issue with Aquinas, of course, arguing that the moment of conception is the point where soul and body are joined. The only problem with both of these views, however, is that they depend on a dualistic metaphysics that no longer has much scientific or philosophical credibility. To put it bluntly, the idea that a human being is a composite consisting of an immaterial soul and a material body is no more tenable than the idea that the earth is flat.
To make my point clearer consider the case of phlogiston, hypothetical substance pre-modern "scientists" invented to explain why a candle goes out when a glass covers it. These ancient thinkers believed that every flame emitted an invisible and undetectable substance called phlogiston. When a candle was covered by a glass, these thinkers reckoned, the flame would extinguish itself after a matter of moments when there was no more room under the glass for the flame to release additional phlogiston. Needless to say, with Lavosier’s discovery of oxygen in 1778, the entire rationale for phlogiston evaporated. Today, most neuroscientists and philosophers find the idea of a soul is about as useful to their work as the concept of phlogiston is to a modern chemist.
Those on the religious right who oppose stem cell research involving human embryos tacitly rely on the outmoded concept of the soul as an immaterial substance. Invoking cliches like "the sanctity of life" to defend the inalienable rights of an embryo is more effective rhetorically than factually. An embryo is not a person, anymore than a recipe is a soufflé.
Nevertheless, embryos can and should be treated with respect because under the right conditions they could develop into persons. Embryos are like seeds. But just as crushing an acorn is not the same as cutting down an oak tree, so discarding an embryo is not the same thing as killing a person. After all, few of us would want to see a doctor or a nurse at a fertility clinic charged with negligent homicide if they inadvertently mishandled a frozen embryo in a way that ended its viability.
Those who oppose federal funding for research involving embryonic stem cells have succeeded in erecting a mountain of impediments to medical research out of a moral molehill. Frozen embryos are routinely discarded by fertilization clinics as a byproduct of helping infertile couples have children, but Bush’s stem cell policy does nothing to "save" these embryos (and no one seems to be clamoring for a ban on in vitro fertilization).
An embryo is not a person. It is estimated that as many as seventy-five percent of embryos spontaneously abort; and in most cases a woman never even knows she was pregnant. Further, two weeks after the supposedly magic "moment of conception" (its actually a biological process that takes hours) a single embryo can begin a process that leads to twins. In other words, it makes little sense to think of an embryo in its earliest stages as an individual.
Stem cell research is filled with promise and fraught with peril. The breakthrough that involves turning skin cells into pluripotent stem cells (cells that could potentially grow into any organ or body tissue) seemingly overcomes a supposed moral issue, but the dilemma here was always more political than ethical.