I admire your tenacity, John, but you’re sticking with the kind of argument my beloved but not-too-gentle graduate school supervisor used to call a “no hoper.” It can’t be made to fly. Modern embryology establishes a set of facts about embryogenesis and early intrauterine human development. These facts are stubborn; there is no running away from them. Human embryos are not creatures different in kind from human beings (like rocks, or potatoes, or alligators); they are, rather, human beings–distinct living members of the species Homo sapiens–at the earliest stage of their natural development. They differ from human beings at later developmental stages not in virtue of the kind of entity they are, but rather by degree of development. That’s why Leon Kass is right to refer to human embryos as “nascent human lives.” Each of us who is now an adult was, at an earlier stage of his or her development, an adolescent, a child, an infant, a fetus, an embryo. Each of us, by directing his or her own integral organic functioning, developed himself or herself from the embryonic into and through the fetal, infant, child, and adolescent stages, and into adulthood with his or her determinateness and unity fully intact. We didn’t begin as non-human or subhuman or prehuman creatures who were later somehow transformed into human beings. Such an idea is risible from the vantage point of modern embryology and developmental biology. We came into being as human beings and developed by a gradual and gapless process of maturation into adulthood many years later. None of us was ever an ovum or a sperm cell—the gametes whose union brought us into existence were genetically and functionally parts of other human beings. But each of us was once an embryo—just as each of us was once an adolescent, a child, an infant, a fetus. To be sure, each of us began his or her life in a state of profound dependency, but that state was not overcome until well after we were born. What we required in the embryonic, fetal, and infant stages is what any human being requires at any stage of life, namely, decent health, nutrition, and an environment hospitable to our survival.
Now, I submit that this evidence (and if you want more, I’ve got plenty of it; please don’t hesitate to ask) establishes that human embryos are human beings in the earliest developmental stages (zygote, morula, blastocyst, etc.)—”nascent human lives.” But you insist on denying it. Why? Wisely, you do not question the scientific evidence itself. But, then, what do you put up against it? I thought that you were offering the fact that there is a “natural” embryo loss rate of 25% or more. But from that fact absolutely nothing follows logically about the status of human embryos. I pointed out (as did many readers) that it is a non-sequitur to suppose otherwise. And in your later posting, you concede the point: “it is true that it does not follow that a 25% embryo failure rate means embryos are not human beings.” But then you claim to be making a different point that is compatible with the point you conceded. What is that point? It is, you say, “that the presumption that embryos are human beings cannot be proved by science and logic alone.” Well, that’s an interesting claim, but what is the evidence for it? After all, the scientific case seems compelling on its face. (That’s why I’m not getting any takers from the pro-embryo-destructive research side on my proposal to leave religion out of the debate and agree to resolve the dispute “on the basis of the best scientific evidence as to when the life of a human being begins.”) The only evidence you’ve given is . . . the fact of a 25% rate of embryo loss. But, since you’ve now conceded that “it does not follow that a 25% embryo failure rate means that embryos are not human beings” you’ll need something else.
You say that the “25% failure rate killing off human life ‘naturally’ is a matter of horror to me . . . and I need something more than nature to make it tolerable.” I sympathize. But the world is filled with inexplicable death and tragedy. It is real. It cannot be wished away or evaded by adopting metaphysical principles that purport to erase empirical facts. As many readers have observed, for most of human history (and in some places even today, alas) the infant mortality rate approached 25%. (You made the interesting point in one of your postings that perhaps the Talmudic saying about the embryo being “like water” was designed to protect people from the emotional consequences of bonding too early to children they had conceived when the chances of death before or shortly after birth were very high.) But the historically high rate of infant mortality does not justify our concluding—on the basis of a “need [for] faith” or the “need [for] the sense of a divine plan” or any other basis—that infants are not human beings. In considering inexplicable death and tragedy, whether we are talking about the death of embryos, infants, or children and adults who die (sometimes by the tens of thousands) in natural disasters, perhaps the best we can do is to face the facts head on and say with Job, “the Lord gave and the Lord hath taken away; blessed be the name of the Lord.” As far as I know, no one has improved on that stance. If faith or religion is to be brought into the discussion, perhaps here is the place to do it. That place is certainly not in trying to determine whether, in the embryonic stage of our development, we were human beings or creatures of some other kind. That is a question to be resolved by scientific inquiry, understanding, and judgment.
If as a matter of faith someone is determined to stick with denying the humanity of the embryo, then I’m afraid I do consider it a “failure of logic.” Far from demonstrating “the limits of logic,” it strikes me (if you’ll forgive my candor) as a refusal to face up to the verified facts. Such a posture makes faith reason’s enemy. But surely that isn’t what you want to do. Reason cannot tell us everything we need to know; faith has its essential role (even epistemically). But a faith worth holding won’t reject what reason firmly establishes. A sound faith will view reason as the truest of true friends—even when the facts it discloses are unpleasant and the truths it teaches are hard and uncomfortable ones.