Bob: No, the blastocyst (really, zygote at this point, but I’ll defer to the more all-encompassing term “embryo”) will not survive unless it is attached to another living organism that you call a “host” and that I call “the mother.” But, again, this is perfectly consistent with the characteristics of human life at this particular state of growth and development, so it provides no evidence refuting the humanity of the embryo. A neonate, after all, is dependent on her mother’s breast milk in order to survive. If you think about it, in some way or other, we all need each other. I’m not sure what the basis of your claim is that an embryo in an ectopic pregnancy will continue to grow but not like anything we would call human. An ectopic pregnancy is one where the embryo implants outside the uterus, almost always in the fallopian tube. In half of these cases, the embryo dies from lack of nutrition and the remains are sloughed away. In the remaining cases, the embryo grows to a point where the fallopian tube will rupture, resulting in the death of the embryo and in severe bleeding/infection for the mother. There are, of course, those extraordinarily rare cases of an abdominal ectopic pregnancies where the child as actually been brought to term. None of these cases, however, provide evidence refuting the humanity of the embryo. In your discussion on the debate about the beginning of human life, you’re conflating the question of when human life begins with the question of legal personhood. Perhaps you’re unaware that, thanks largely to the abortion rights movement, human life and legal personhood are now two distinct concepts. Yes, one would think that human life and personhood would go hand-in-hand, but in our morally insane culture it’s now possible to be a living human being, even a living, breathing human being, and not enjoy the status of legal personhood. Hence, the Virginia law where a child fully ex utero, but still attached to the umbilical cord and the placenta still within the mother’s uterus is not legally a person, so the state had no grounds on which to prosecute a mother who killed her newly born child (“Campbell County mother can’t be charged in baby’s death,”www.nbc12.com, 2009). The debate you reference in your post is not a debate over when human life begins, but a debate on when it is deemed best to assign legal personhood to the unborn (or, in some cases, already born) child. This distinction between human life and personhood is disconcerting, for it can be possibly be applied to all kinds of people. There is already serious talk about “fourth-term abortions,” and I mentioned Peter Singer’s ominous ideas. But, for the sake of the argument, let’s say you’re right, and the science of when human life begins is unsettled. The argument in favor of abortion based on the non-humanity of the one in the womb still fails. Why? Because in cases where we can’t be certain whether or not we’re destroying innocent human life, if we truly don’t know, then we must presume in favor of life. Consider a hunter who sees the rustling of leaves and branches in the bushes. Is it a deer? Is it a man? Is the hunter ever justified in shooting if he doesn’t know? Or consider a contractor hired to raze a building. He thinks he sees movement through a window. Is it shadows? Is it the wind through a window? Is there someone in the building? He doesn’t know. Is he justified in razing the building before he’s certain? You argue that the question of when human life begins is unsettled. Yet, you justify abortion on the grounds that we can’t be certain the one in the womb is human life, rather than the grounds that we’re certain it isn’t. You are effectively telling the hunter to shoot, and the contractor to raze the building. When you can’t be certain, you presume against life rather than for it. that is morally unsustainable.