The idea that there are intrinsically evil acts—acts that are always and everywhere wrong no matter what the circumstances or consequences may be—is often challenged by appeals to extraordinary cases, real or imagined. Killing one innocent person, it is said, though obviously wrong in most cases, may be justified if it is the only way to save fifty others. Or adultery, though morally bad in general, can hardly be considered wrong in the case of Mrs. Bergmeier, for whom it was the only way to get out of prison and rejoin her family.
I have always found such arguments troubling, especially when they are used extensively in the classroom. Rather than nourishing, clarifying and strengthening the basic moral principles our students come in with, such reasoning tends to obscure and weaken those principles. Instead of helping students to understand why certain acts are offensive to God and a violation of the dignity of persons, such arguments encourage them to consider in what circumstances they might be willing to perform them. Whatever the philosophical merit of such reasoning is, and I don't deny there is some, I think it damages our moral imagination and tends to undermine our moral commitments.
All this came to mind while I was reading Bernard Williams' excellent critique of utilitarianism. It is the feature of a good person, Williams implies, that he regards
…certain courses of action as unthinkable, in the sense that he would not entertain the idea of doing them: and the witness to that might, in many cases, be that they simply would not come into his head. Entertaining certain alternatives, regarding them indeed as alternatives, is itself something he regards as dishonourable or morally absurd.
To many this attitude looks like intellectual cowardice, like nothing more than a stubborn refusal to think through ethically demanding situations. And there may be something to that. But normally, it seems to me, this attitude reflects a kind of inborn wisdom. It is connected to an awareness that our knowledge and responsibilities are limited; that we are called to stand our ground and do our part, and to leave the consequences to God's providence.