Abortion, contraception and Christian tradition

It is traditional Christian teaching, as far back as we can trace it, that:

1. Abortion is always wrong.

Nonetheless, historically many Christian theologians, such as Thomas Aquinas, accepted the best science and philosophy of the day (Aristotle!) which held that:

2. Human existence starts about a month and a half after conception.

Our science no longer teaches (2), of course: it is scientifically clear that we have the same organism at conception—or at very latest at implantation—as at birth.

However, for those of us who think that Christian tradition carries significant epistemic weight, it is interesting to ask why it was that historically Christian teaching stalwartly affirmed (1) despite many Christian thinkers accepting (2). I see two hypotheses each of which may explain this puzzle. Both hypotheses may be true (and indeed I think they are).

The first hypothesis is that (1) is simply a datum of the apostolic teaching of the early Church (it is after all found in the first-century Didache). The Church’s stalwart acceptance of the prohibition of abortion notwithstanding the tension between this prohibition and the best science of the day is a sign that the prohibition of abortion was grounded in divine revelation rather than philosophical speculation.

The second hypothesis is that the reasons for the traditional prohibition of abortion are logically independent of the moral status of the embryo or early fetus. We also know that the early Church forbade contraception. If the embryo or early fetus is not a human being, the an early abortion may not be morally very different from contraception. But the Church was opposed to contraception. Via this second hypothesis, the apparent tension between the blanket prohibition on abortion and the philosophical and scientific views on the beginning of human life is further evidence for an apostolic prohibition of contraception.