David B. Rivkin Jr. and Lee A. Casey have written a series of thoughtful articles on the intersection of law and counterterrorism. In today’s Wall Street Journal, they take up the question of torture, attacking those critics of the Bush administration who, while condemning the coercive interrogation methods it has used in the war on terror, conspicuously omit to say which techniques they themselves regard as legitimate.

This is a fair point. But the authors’ own reasoning has some shortcomings of its own.

Drawing on published reports, Rivkin and Casey note that the Bush administration at various junctures has used “slapping, exposure to cold, stress positions, interrupted sleep and waterboarding, alone or in some combination” in the interrogation of al-Qaeda prisoners. The Justice Department, they say, “has reportedly approved all of these as legal.” And while “[r]easonable minds can disagree with this finding,” they assert that it is “unlikely that Justice signed off on these methods without regard to the level of intensity or potential cumulative impact” on the prisoner. In other words, the Department of Justice had grounds to conclude that the methods did not amount to torture.

But that is precisely the point in contention. After all, the Department also signed off on a memo saying that only methods that caused “organ failure, impairment of bodily function, or even death” constitute torture and are punishable by law. All other methods were presumably permissible. That memo was subsequently repudiated and withdrawn. Michael Mukasey, testifying in his confirmation hearings, called the memo “worse than a sin. It was a mistake.”

In his testimony, Mukasey was also asked directly about waterboarding, a procedure which simulates the feeling of drowning. First, he said it “is not constitutional for the United States to engage in torture in any form, be it waterboarding or anything else.” But he then backed away from such precision, saying about waterboarding: “I don’t know what’s involved in the technique. If waterboarding is torture, torture is not constitutional.”

Is waterboarding torture? Rivkin and Casey explain that it “has been part of U.S. military training programs on interrogation resistance.” From this they conclude that the practice is not torture, because if it were, “then it is impermissible for all purposes–whether or not an individual has consented.”

But this does not follow. Consent makes the context entirely different. No one is compelled to endure military training of that sort, which is only for elite, volunteer units, in our all-volunteer military. Being subjected to extreme cold while naked in a cell against one’s will is very different from being subjected to extreme cold as a consensual member of the Polar Bear club that swims every New Year’s day in the Atlantic Ocean.

Rivkin and Casey make some tentative judgments that also strike me as peculiar: “Slapping a man’s face probably does not cause him severe pain. Breaking his nose probably does.” “Probably”? I would think it is more than that, but perhaps I am wrong. Are we now forced to hold a debate about the meaning of the phrase “severe pain”?

However much it hurts to have one’s nose broken, the fine distinctions the authors are attempting to draw here should cause us to take note of all of the interrogation techniques that the U.S. military is not using, and has never contemplated using, from the rack of the days of yore to the electric drill applied to the head or limbs, a favored al-Qaeda technique.

The entire discussion of torture in which Rivkin and Casey and others are engaged demonstrates that we are a humane society attempting to remain humane while protecting ourselves from those who are not. But if we as a country are going to find a defensible position, it will have to rest on arguments that themselves can survive interrogation.