The divisions on the question of how to deal with terrorist suspects reminds us that there is confused reasoning in town. This is not unexpected, but this time around it gives especially interesting paradoxes.

Senator McCain — miraculously still alive, given what he was made to suffer in Vietnam — voted against authorizing “alternative interrogation practices,” rejecting the toughness President Bush and his advisers deem necessary to cope with their problem. Most unexpected was the intercession of Colin Powell. As a former secretary of state and close adviser to presidents, he’d have been thought in favor of executive authority in matters touching on war.

Representative Duncan Hunter of California, head of the House Armed Services Committee, said simply that he would do whatever the president asked. General Powell introduced an objection of arresting nature. He said that a departure from the Geneva Convention rules would encourage the world to “doubt the moral basis of our fight against terrorism.”

It’s worth it to pause for a minute with some basic questions, illuminated by a hypothetical case.

Habib Sulaiman, age 22, is picked up by security agents in London. He has been frequenting the airport, spending unaccountable time at international departures gates of British Airways. A search of his apartment brings out files focusing on airport transport. Telephone records disclose calls to a number that French authorities have listed as suspect. Mr. Sulaiman declined to answer any questions. One month later, he finds himself in Guantanamo. What is to be done with him?

Routine questioning, of the kind he has been subjected to ever since he was picked up, has accomplished nothing.

Hypothetically, he could be shot and buried. But of course we do not do that kind of thing.

We could just keep him in his Guantanamo cell. Just keep him there, let the months go by, turning — maybe — into years. But that, too, is something we don’t go in for, certainly not in theory.

So after a while the commandant says,”Let’s try something a little more persuasive than solitary confinement.”

Like what? Like alternative interrogation practices.

A question before the Senate was whether to continue to abide by what is called Common Article 3. The Geneva Convention that begot Article 3 sought to prohibit inhumane treatment of combatants seized in wartime. In the language of the convention, the design was to prohibit “outrages upon personal dignity.”

Legal questions arose. General Michael Hayden of the CIA has said that clarifications have to be made, since outrages to human dignity can be adduced by imaginative, and even not really imaginative, detainees — certainly Mr. Sulaiman could after awhile persuasively maintain that life in a cell in Guantanamo is an outrage against personal dignity.

Another matter, on which Mr. Bush is absolutely decisive, has to do with the auspices of Common Article 3. The Geneva Convention that came up with it was talking about treatment of organized combatants, and of course terrorists are militantly non-military. The point here is that Congress has the authority to modify its endorsement of the Geneva protocol by acting on the vagueness not only of the prohibition, but also of the category — “combatants seized in wartime” — being dealt with.

It was a maudlin mistake of General Powell to take these questions and run them together under the rubric of morality. The eternal question, in international engagements but also in national and even local engagements, is how to balance competing claims: the claim to personal sovereignty and the claim to security for the community. Before airplanes existed, one didn’t need expedited detentions based on suspicious activity.

As Congress closes in on the request of the commander in chief, elected legislators will need to review these questions. They should not be asked to define what exactly they condone, in the way of alternative interrogation practices. But they should not be dumbfounded into inactivity by general appeals to the Ten Commandments.