I’m not sure how comfortable you feel with approaching the issue philosophically, but the case against abortion is fairly straightforward and simple. Dr. Peter Kreeft has a wonderful way of getting at the issue, and you can find it on his website (
peterkreeft.com) and I believe he has a couple of books on the issue. He lays out four possible circumstances:
(1) A fetus is a human being and you know that it is.
(2) a fetus is a human being and you do
not know it.
(3) a fetus is
not a human being and you do
not know it.
(4) a fetus is
not a human being and you know it.
On (1), abortion is obviously tantamount to murder of an innocent. But if that is true, than one either has to say that murder is not morally wrong or that abortion is not morally permissible. If a person affirms the former, I can only say that the person is morally blind.
On (2) and (3), abortion is no different than gross negligence of human life. Consider, for example, if I were on a hunt and saw a rustle in the bushes. Suppose also that I had no means of really knowing whether or not the thing in the bushes was an animal or a fellow hunter. If I were to shoot despite not knowing for sure that it was an animal, I would be negligent of my fellow hunter’s life
even if it really was an animal. So, the only moral option would be not to shoot as long as I am in a state of ignorance as to the nature of the thing in the bushes. From this analogy, it is plain that abortion should be condemned if it is the case that we are unsure about whether or not the fetus is a human being or simply a mass of cells.
The only possible case in which abortion would be permissible is (4). But the fact is that we have absolutely no evidence that tells us a fetus is not a human being. Indeed, we have evidence to the contrary. It is blatantly obvious, at least, that biological life begins at conception. At conception, the fetus has it’s own, uniquely human genetic code and thus an internal principle of growth. It is nothing other than a developing human being, only differing in degree from the new-born, the toddle, adolescent, and adult. Thus, it must be substantially human. At no point in time after conception is it possible to point to a formal change from one kind of thing to another. Conception is this type of change. Given that we need this formal change in order to attribute humanity to a thing, and the only time this type of change occurs in the development of human life is at conception, it follows that we should attribute humanity to the fetus. Otherwise, the attribution of humanity to any subject whatsoever would be totally arbitrary (and therefore meaningless). So abortion should logically be considered the killing of a human being.
So your friend can only possibly support abortion if he has pioneered some new and unheard of research that
proves definitively that fetuses are not human beings. If he says he has, then we can only pray that he be loosed from such delusions.