Pascal-Emmanuel Gobry on the great abortion question of our time:
The biological, moral and legal status of the unborn child isn't a question of metaphysics.
Whether life begins at conception isn't a matter of religious faith, it's a scientific question, and the answer isn't very hard. Of course, you can choose to disbelieve it, just like you can choose to not to believe that CO2 molecules redirect infrared variations.
Now, science isn't a moral guide. The fact that a fetus is a living human being doesn't necessarily entail that it should receive legal protection. But again, resolving this issue requires no recourse to metaphysics.
It requires asking what are the criteria for qualifying as a person endowed with rights.
I'm afraid there's some semantic hairsplitting going on here. Of course a fetus is life; so is a human egg, and so is a human sperm. That's never been at issue. But in the context of abortion, life is just shorthand for human life, and whether a blastocyst or a fetus qualifies as human is very much a religious and metaphysical question. It's certainly not a scientific one.
The list of criteria for being a person endowed with rights starts with being a human being. Those of us in the pro-choice camp don't believe that the mere presence of cellular machinery and a human genome makes one a human being. Those in the pro-life camp do — though I'd note that for many of them, their actions don't back up this professed belief.1 But whichever camp you're in, this isn't a question that science can answer. Pretending otherwise is little more than a tawdry rhetorical trick designed to give your arguments an authority they haven't earned.
1If you really, truly believe that a fertilized egg is a human life, your opposition to abortion will be absolute with the sole exception of abortion that's necessary to save a mother's life. You won't support exceptions for rape and incest any more than you'd allow the killing of a child who was the product of rape or incest. You'll also oppose fertility treatments, which routinely create and destroy more fertilized eggs than they use.
Some pro-lifers do indeed feel this way. But many don't. At a visceral level, these semi-opposers obviously have an aversion to abortion that stems from some source other than a belief that human life begins at conception.