"The devil's most devilish when respectable," wrote poet Elizabeth Barrett Browning. A recent reader note to Boundless brings that quote to mind.

Before we get to that note, though, we need to get a bit of background. Flash back a decade or so, when a professor named Eileen McDonagh put out a book called Breaking the Abortion Deadlock.

McDonagh didn't bother to deny that a fetus is a person. Instead, she argued that a fetus is, in effect, a criminal — a "powerful intruder" guilty of "kidnapping" a woman and holding her hostage for nine months — and thus could be dispatched like any violent assailant. "The fetus is not innocent," she wrote, "but instead aggressively intrudes on a woman's body so massively that deadly force is justified to stop it."

Reaching for analogies, McDonagh compared an unborn child to a rapist. You can't expect a woman to endure a pregnancy to support her assailant, she said: "This type of reasoning is akin to saying that a woman being raped should wait till the rape is over rather than stopping the rapist." And you can't protest that the preborn child has no malicious intent: Neither would a mentally incompetent rapist, McDonagh argued, but you still have the right to shoot him.

Though some feminist groups (the National Organization for Women among them) leaders hailed the book, few others raced to embrace it. To all but the most radical feminists, talking as if the unborn child were The Enemy is, in a word, bizarre. No one seemed to talk about the book for long, and I, for one, figured not much would come of it.

But the ideas, which previously had been kicked around mainly by people on the academic fringes, were out there now. If only they could be made more presentable ... cut the inflammatory language, make the whole thing sound more appealing and mainstream....

So variants on McDonagh's ideas kicked around some more for a few years. They popped up in classrooms and journals and Web sites here and there, filtering their way into various people's minds.

And a few weeks ago, when they popped up in a reader's note to Boundless, I realized I'd been too optimistic.

"I recently heard the following pro-choice argument," she wrote, "and I'd appreciate someone tackling it who is more skilled at constructing arguments than I am."

The argument is this: It doesn't matter at what point a fertilized egg becomes a zygote or a zygote a fetus or a fetus a baby. Personhood is irrelevant. The state simply does not have the right to require any citizen to use their body to keep another citizen alive, much less for nine months. The state can't force us to donate blood or organs. The state can't make us sign up for bone marrow registries. If we choose to do these things, it is noble and good, but we still would never tolerate, as a society, being forced to do so. How much less, then, should we tolerate the state forcing women to use their bodies to keep other people alive for nine full months, with all the risks and permanent changes in the body this entails? How is this permissible if women are fully functioning moral agents with all the rights of citizenship and not state-owned incubators?

I can see why our reader isn't sure how to respond to this argument. There's no strained effort to liken unborn children to vicious criminals, no loaded language about "intruders" and "rapists" and "kidnappers," no brutally candid calls for "deadly force." Instead, there's a lot of talk about women and their rights versus the state. And yet, this essentially is McDonagh's argument: It's just been repackaged. The preborn are seen chiefly as afflictions. Women are seen as victims of violation, albeit less by the child than by "the state."

Actually, I'm a little unsure how to respond to the argument myself — not because it's so good, but on the contrary, because it's so warped. I have to take a breath, take time to absorb just how morally unhinged it is.

Yet the argument isn't hard to refute. Like McDonagh, it doesn't deny that a fetus is a person. ("Personhood is irrelevant," in the Borg-like phrase.) It simply claims that pregnancy is too much trouble: No one can rightly be required to go to such lengths to save another person's life. But do any of us really believe that? Let's try a simple test of human decency.

Imagine being stuck on a desert island alone with an infant. Needless to say, caring for him, in addition to staying alive yourself, is an all-consuming task. And it could take a lot longer than nine months: For all you know, it could take many years. But would you ever dream of deciding: "Looking out for this kid is just too much trouble. I didn't ask for the job, so I'll just abandon him. I'm only exercising my rights, after all."

Almost certainly your answer isn't just "No," but "Of course not." You'd have to become a monster to do something like that. If you even found yourself thinking seriously about it, you'd be horrified. You'd feel your own humanity, your very soul, slipping away. You'd be flirting with pure evil, and you'd know it.

That example, I think, should illuminate what's at stake here. The principle is very basic: If you are a baby's only hope to survive — if there's no one else who can do the job — you could never walk away, much less invoke your "right" to do so. Period, exclamation point.

There's no avoiding how the principle applies in the case of abortion, once you accept that a human life is at stake. You can try claiming that it's not the government's business to uphold the principle. But that claim's hard to take seriously: Protecting innocent life is a government's most fundamental duty.

All these things seem so clear, you have to wonder: Where do arguments like McDonagh's — in any of their forms — come from? The answer, I think, can't be found in the realms of philosophy or logic. Even when these arguments use the dry, intellectual language of academic disciplines, I think they stem from corruptions of the mind and of the heart.

"The human mind is never more resourceful than when it is involved in self-justification," author Jean Garton has written. Truer words were never spoken. We can always find some excuse, and we can usually find a way to make it seem respectable.

That doesn't change the fact that God made us to know what's right. All we have to do is picture ourselves with that infant on that desert island.