Let us now praise Realpolitik.

Imagine a regime that in the space of five years manages to commit aggression, piracy, terror and torture -- and follows up with poison gas. Consider Iraq. 1)Aggression: It started the Gulf war in 1979 hoping to grab Iranian territory. 2)Piracy: It routinely attacks unarmed shipping ("naval targets") in international waters. 3)Terror: For many years it sponsored one of the world's great murderers, the terrorist's terrorist, Abu Nidal. 4)Torture: The "authorities" use "both physical and psychological torture" against political op- ponents, according to the State Department's 1984 Human Rights Report. And last month, yet another round of poison gas attacks on Iranian troops.

Quite a record. It puts Iraq in a moral league of its own. And yet six months ago the United States reestablished diplomatic relations with this regime and its staggering list of crimes, and not a peep of protest was heard. Not a word about dirty hands, American values, or any of the high principles trotted out whenever, say, a dissident is rudely shoved (no bruises) by South Korean police. Not a word. Poison gas does elicit a disapproving statement from the State Department and a few grumbles from Congress and editorialists, but no call for anything beyond words.

The reason is brutally simple. We want Iraq as a bulwark against Iran. So we swallow the rest.

This is not our only excursion into the unsavory world of Realpolitik. Another thing we want is Afghanistan as a bulwark against, or at least a trap for, the Soviet Union. We are prepared to swallow a lot here too.

Two things in particular. First, the Afghan guerrillas' aversion to taking prisoners: They have a habit of killing them.

Second, the Afghans' goals: They proclaim themselves Islamic warriors. The largest of the guerrilla alliances is Islamic fundamentalist. Its closest model is Khomeini's Islamic Republic. (Rememlass criminality in Baghdad to stop just this sort of Islamic fanaticism from Tehran.)

And yet Afghanistan is perhaps the holiest cause on Capitol Hill. Congress is consistent and unanimous in its support for the rebels.

March 21st was "Afghanistan Day" in the United States, so declared by a Joint Resolution of Congress passed by unanimous consent. On Oct. 4, 1984, the House passed, also without dissent, the Ritter resolution "to encourage and support the people of Afghanistan in their struggle to be free from domination" and "to provide the people, if they so request, with material assistance . . . to help them fight effectively." Last Sept. 13 a reception was held in the Rayburn House Office Building in honor of an Afghan guerrilla commander. Sponsors of other events for the Afghans have included such stalwart human rights advocates as Barney Frank, Tom Lantos, Paul Tsongas and Claiborne Pell.

I'm puzzled. Congress becomes apoplectic when it receives reports of human rights violations by the Nicaraguan contras, which violations, even if they are all to be believed, appear to be the result of indiscipline. In Afghanistan, on the other hand, killing prisoners is guerrilla policy.

The other congressional charge against the contras it that they are insufficiently democratic. In fact, most of the contra leadership and its allies -- from Alfonso Robelo and Arturo Cruz on down -- are democrats who opposed Somoza. Admittedly, some contra military commanders served Somoza. Fine. But if that argues against helping them, what are we to make of the Afghans? To what kind of democracy does Congress think the mujahedeen are committed?

Double standards in foreign policy are always hard to avoid. But this standard is wildly double. One guerrilla army doesn't take prisoners and wants to establish an Islamic theocracy; it is on moral holiday in the U.S. Congress. The other, imperfectly democratic and with a troubling, though hardly exceptional, record of abuses is to be cut off for failing to meet Jeffersonian standards.

Some congressman to whom I pose the question argue that the crucial difference here is Soviet occupation. But by what moral logic are standards of human rights and democracy to be applied to those fighting domestic tyranny and suspended for those fighting a foreign variety?

I suspect that human rights and democracy have nothing to do with it. The silence that greeted our rapprochement with Iraq shows that Americans can play as cool a game of Realpolitik as anyone. Similarly our indifference to the means and ends of our Afghan brothers. And who can blame us? It is important that Iran be stopped. It is also important that the Soviet Union be stopped. We must take our allies where we find them.

But why, then, the constant moral posturing about the contras? Their offenses and deviations from democratic practice are infinitely smaller than those of the Afghans. Can it be that those so selectively indignant about the failings of the contras are not making a moral argument at all, but are using one to disguise weariness for yet another long twilight struggle, this one so inconveniently close to home?