Via Leiter, I see that some people are wrong on the internet:

Perhaps you already observed it on Friday, since that was the anniversary of the bombing of Hiroshima. But today, the anniversary of the Nagasaki bombing, is an equally fitting date. Certainly the image above – the aftermath of Fat Man’s explosion over Nagasaki – is a fitting symbol for consequentialism. Perhaps consequentialist ethicists should consider putting it on the covers of their books, or wear little mushroom cloud pins when they meet up at philosophical conferences. For one thing, since the consequentialist case for the bombings – that they would save more lives than an invasion of Japan would – carried the day with the Truman administration (and with defenders of the bombings ever since), it may be the most consequential piece of consequentialist reasoning ever formulated. For another, the bombings give a pretty good idea of what a world consistently run on consequentialist principles might look like.

But don’t put the party hats on yet, because there’s one little hitch: Consequentialism is, as David Oderberg has put it, “downright false and dangerous, an evil doctrine that should be avoided by all right-thinking people.” And the bombings of Hiroshima and Nagasaki were, accordingly, as evil as consequentialism is. So, maybe Consequentialism Day is not a good idea after all, except perhaps as a reminder of the scale of evil that can be and has been done in the name of “good intentions” and “rationality.”

Jimmy Akin offers us a helpful reminder of why the bombings must be considered gravely immoral from the point of view of natural law theory and Catholic moral theology. It is only fair to acknowledge that many consequentialists would no doubt also condemn the bombings, arguing that better consequences would result overall and in the long run from respect for a rule that forbade such actions. Whatever. What matters is that any consequentialist must allow that it is at least in principle legitimate intentionally to kill the innocent for the sake of a “greater good.” And from the point of view of us reactionary, bigoted, unprogressive natural law theorists and Catholics, that is enough to make consequentialism a depraved doctrine. For it is never, never permissible to do what is intrinsically evil that good may come – not even if you’d feel much happier if you did it, not even if you’ve got some deeply ingrained tendency to want to do it, not even if it will shorten a war and save thousands of lives. Never.

(I actually have a little “fat man” bomb-shaped pin that I got at the Atomic Testing Museum in Las Vegas. Almost as fun as the Liberace museum! But that’s not important right now.)

Clayton Littlejohn has a go at a response in comments. To his sensible points, I’d add the following fairly obvious ones:

(i) first, it’s not at all clear that Truman et al. actually gave any thought to consequentialism in thinking about the bomb. Nor is this relevant, in itself. What we’re interested in is the question of consequentialism’s truth, not the reasoning of the Man from Independence.

(ii) There’s another reason it’s misleading to say that “the consequentialist case for the bombings…carried the day with the Truman administration.” Paradigmatic versions of consequentialism weight outcomes for all affected parties equally. That is, the evaluation of the goodness of consequences considers all affected, not a subgroup. Though I’m no historian, I’m willing to bet that decisionmakers weighed American lives (American levels of well-being, pleasure, whatever…) over Japanese lives. Complication: I would classify moral theories that examine effects on only a group or single individual (“group chauvinism” or egoism) as consequentialist, kinda sorta, but they’re a limiting case and the classical versions build in the “all for one, none for more than one” commitment.

(iii) Consider this:

What matters is that any consequentialist must allow that it is at least in principle legitimate intentionally to kill the innocent for the sake of a “greater good.” And from the point of view of us reactionary, bigoted, unprogressive natural law theorists and Catholics, that is enough to make consequentialism a depraved doctrine

Here, let me shorten it. “Natural law and consequentialism are very different moral theories and they disagree about many actions.” If you think NL is right, you’re not a Cist, and vice versa; of course adherents of one theory think the adherents of another are wrong about morality.

(iv) And this:

For it is never, never permissible to do what is intrinsically evil that good may come – not even if you’d feel much happier if you did it, not even if you’ve got some deeply ingrained tendency to want to do it, not even if it will shorten a war and save thousands of lives.

The consequentialist disagrees, of course, though “if you’d feel much happier” and “if you’ve got some deeply ingrained tendency…” are not going to be relevant in most cases. “If you could save thousands…” is more likely– but if you really could save thousands by murdering one innocent, it’s not so obvious that the murder is wrong, etc. Cue phil 101 discussion.