Abortion, Alasdair MacIntyre, and Nestorianism

Reflecting on three recent articles and how they have a common thread to them: the incommensurability of rational justification

The late great moral philosopher Alasdair MacIntyre (1929–2025) argued for the incomparability of moral reasoning. We have no standard by which to adjudicate different moral conclusions because we cannot agree on what rationality itself is.

How did we come to this place? MacIntyre explains that Enlightenment thinkers aimed to justify public standards by supplanting authority and tradition rationally. However, the results of such a pursuit led to various forms of rational justification (Whose Justice? Which Rationality?, 6). And at the same time, such thinkers also eliminated traditional structures of rationality (WJWR, 7).

We now live in a world where moral reasoning has fractured, and we pretend to have consensus when in reality we have no agreed-upon justification for almost any action we take today.

Let me give two examples of what I mean.

Abortion

I recently published an article that asks the question whether or not the Bible speaks about abortion. Some authors like Richard Hays will say no (at least when it comes to the New Testament): "The Bible contains no texts about abortion." Hays is not alone. Scholars regularly point out that the Bible does not forbid abortion in the modern sense of the term.

But the majority of worldwide Christians strongly believe the Bible does condemn abortion. And in fact, historically, Christians have forbidden abortion. The Didache and other early Christian writers even call it murder—the unjust taking of a life.

The answer partly goes back to MacIntyre's argument. Biblical scholarship today looks for a specific kind of evidence to verify a biblical conclusion, usually one tied to explicit biblical wording corroborated by a preponderance of historical data.

But the Bible does not have a single text that supplies a doctrine of abortion, or any discussion that could include modern medical abortions. The Bible exists in a world before modern medicine, the pill, and modern medical abortions.

But it does exist in a world with a demonstrable view of life and death, a position that God makes life and knows life in the womb, and so by such theological and metaphysical reasoning, we can say abortion unmakes the life that God has made in the womb by human begetting.

But both sets of conclusions are incommensurable, to use MacIntyre's language. One argues from the contingent facts of history, the other from metaphysical principles (without disregarding the facts of history).

Nestorianism

Another example includes how evangelicals recently argued about Nestorianism. On one side, some argued that calling Mary the mother of God could not be true since she only bore the humanity of Christ, that the Bible calls Mary the Mother of the Lord (not God), and that the title Mother of God is Roman Catholic—used to elevate Mary.

None of these claims leads to the denial that Mary is the mother of God. But the evangelical Nestorians believe they are rational. They have been entrapped by the Enlightenment thinking that MacIntyre describes. They can only see dogma if it's verbally contained in Scripture in an exact phrasing—a point of view that would render doctrines of abortion, Trinity, and Christology null.

On the other hand, the fathers knew that the whole Bible taught that the one Lord Jesus Christ made flesh his very own. And so the one Lord Jesus Christ was born of a virgin, made flesh, and died for our sake. To divide the natures of Christ into a human dying or a divinity avoiding death misses the point. Deep reflection on what the Bible teaches drives us to affirm the single subject of Christ died—that he suffered in the flesh (1 Pet 4:1).

For this reason, we can say God suffered in the flesh, since the one Lord Jesus Christ is God. But of course, this requires some nuance since we also need to say that the Son suffered, not the Father or the Spirit. My point in bringing this up is only to say that we are once again facing the incommensurability of truth claims.

While Nestorianism did have some cache in the ancient world, eventually the vast majority rejected its premises because they shared a common rational framework. And one, I might add, that the Holy Spirit providentially informed in their minds. For us, this note is important since we must be careful we do not cut ourselves off from the Spirit's work.

MacIntyre

If you are curious to learn more about Alasdair MacIntyre, I wrote a memorial about him over at TGC that you can read here: