That is just one of the many questions someone ought to be asking about the prisoner abuse scandal, or, more particularly, about the extraordinary reaction it has aroused. The scandal itself is real enough, and deserves thorough investigation. But an investigation, as I understand the word, implies the careful collection of evidence, from which certain conclusions may be drawn. Instead, a great many people have jumped to the most extraordinary conclusions about the scandal's significance, in advance of the evidence. In some cases, this was predictable, coming from critics with a demonstrated antipathy to the war, the United States, or its leaders. But the broader public reaction seems based on nothing more than an emotional reaction to the stomach-turning scenes in the photographs, and the popular assumption that such sensational images must be accompanied by an equally compelling story. Not so: In this case, a picture tells rather less than 1,000 words.

Here are a few things the photographs do not tell us. They do not say whether the pattern of abuse they depict is widespread. At this point, we do not know whether it even extended beyond one particular cellblock at Abu Ghraib, let alone the entire Iraqi prison system. That may have been the case, and it certainly warrants further investigations to see whether this was so: investigations that are already under way, and were well before the scandal hit the media. Confusion on this point has been engendered by two further misunderstandings. It is not true, as some have stated, that the roots of Abu Ghraib lie in Guantanamo Bay, and the doctrine laid down by Mr. Rumsfeld two years ago: that the al-Qaeda fighters captured in Afghanistan would be denied the status of prisoners of war and the rights they enjoy under the Geneva Conventions.

That in itself was a defensible decision -- indeed, it was wholly consistent with the Geneva Conventions, inasmuch as the al-Qaedistas themselves observed none of the laws of war, such as the requirement to fight in uniform, with regular command structures and such -- to say nothing of more serious violations such as using civilians as human shields, stationing artillery in schools, and so on. Part of the reason prisoners of war, as defined in the Conventions, are accorded a special status is precisely to encourage the combatants to stay within the rules while they are in the field. The Conventions, moreover, prohibit any interrogation beyond the proverbial name, rank and serial number. Yet the terrorists, some of them top-ranking al-Qaeda leaders, imprisoned at Guantanamo Bay have in no sense retired from the fight, and would be privy to information that, once obtained, might save thousands of lives. That is quite unlike the case with ordinary soldiers.

In any event, whatever may be the case at Guantanamo Bay, the situation in Iraq is entirely different. The prisoners held there are, by a well-publicized order of the President, subject to the Geneva Conventions, except in a few special cases. The abuse and perversities visited upon the prisoners in Abu Ghraib was, far from complying with military doctrine, directly contrary to it. And not only with regard to the Geneva Conventions: The same practices are also expressly outlawed by the military's own Uniform Code of Justice.

That is not to say that there have not been other abuses, at other military prisons, both in Iraq and Afghanistan. There have, as various Red Cross reports have documented. But for the most part these have been nothing like the sort of sadistic practices that have properly horrified people in the current example. That is the other broad misunderstanding at work here: the confusion of rape and torture with such comparatively routine forms of psychological pressure as denial of visiting rights and sleep deprivation. Perhaps these should not have been employed outside Guantanamo Bay. Perhaps they should. (The Red Cross was scandalized to find that some of Saddam's top henchmen -- the worst of the worst, many of them intimately involved in the insurgency -- were being held in solitary confinement. Oh dear.)

But it is hardly unusual to find military prisons that are sometimes not up to snuff, or even occasional instances of abuse. It happens in every war. It shouldn't, but it does. For that matter, it happens in domestic prison systems, too, and in every country. The test is not whether it happens, but how often, and what steps are taken to prevent it.

There are some legitimate criticisms that can be made of the U.S. administration, and the military, on this score. The command structure inside Abu Ghraib does seem to have been confused, with military police, responsible for the care of prisoners, improperly taking instructions from military intelligence officers, responsible for their interrogation. Lack of training may well have been a factor, perhaps exacerbated by undermanning. But that does not excuse the individuals involved from their own personal responsibility for the crimes they committed. Nor is it proof of a more systemic problem. Evidence, perhaps, but not proof.