Since the book of Genesis does not tell us how Cain managed to find the woman he wed when he was, according to the story, the only person left on earth apart from his parents, we might be justified in concluding that it is actually fratricide that is the world's oldest profession. And in politics, certainly, there are people who find fratricide much more invigorating than prostitution. Sectarian war and the knifing intraparty rift have more usually been associated with the ideological left and the Democrats, while the G.O.P—stolidly nonintellectual and businesslike—supposedly kept its ranks closed, and hewed to the 11th Commandment: thou shalt not speak ill of fellow Republicans. But over the course of the last year, I have been hearing the most astounding kinds of abuse and contempt, flung by competing sections of the American right against one another. Some of this is institutional, representing a turf war among the Defense Department, the State Department, and the C.I.A.: the sort of disputed territory covered by Bob Woodward. But the core of the quarrel is bitterly ideological and reflects profound and essential differences. The catalyst has been the war in Iraq.

Here is David Frum—a former speechwriter for President Bush and the man credited with evolving the instant-fame phrase "axis of evil"—in the National Review:

There is ... a fringe attached to the conservative world that cannot overcome its despair and alienation. The resentments are too intense, the bitterness too unappeasable. Only the boldest of them as yet explicitly acknowledge their wish to see the United States defeated in the War on Terror. But they are thinking about defeat, and wishing for it, and they will take pleasure in it if it should happen.

They began by hating the neoconservatives. They came to hate their party and this president. They have finished by hating their country.

War is a great clarifier. It forces people to take sides. The paleoconservatives have chosen—and the rest of us must choose too. In a time of danger, they have turned their backs on their country. Now we turn our backs on them.

Only the term "paleoconservative," in the above, would make the argument difficult for a layman to decipher. Otherwise, it's admirably plain. Against his Republican opponents, David Frum charges nothing less than conscious, gloating treason—a term that hasn't made a real appearance in American politics for decades.

In the midst of a real war, American conservatives are having a civil war.

If you want a picture of a "paleoconservative"—someone who is a bred-in-the-bone all-American hardliner and enjoys reminiscing about the great days of Barry Goldwater and Ronald Reagan, with a side bet on Joe McCarthy—just keep the image of Patrick Buchanan in your mind. Here is what Buchanan wrote in his syndicated column, in reply to David Frum and his ilk:

With Iraq turning into the Mesopotamian morass some of us warned it would become, the neo-Jacobins have decided they are not going to be the ones to ride the tumbrels. In times like this, character comes through. By turning on the men they persuaded to go to war, by fabricating alibis and inventing excuses to absolve themselves of culpability for what they labored to create, they have revealed themselves for what they are: hustlers and opportunists devoid of principle, driven by an ideology of power and a passionate attachment to a nation not their own.

The Old Right curmudgeons who warned us against giving these vagabonds food, shelter and a warm place by the fire were right. We should have put them back out on the street....

With the situation in Iraq deteriorating, the neocon agenda is to widen the war into Syria, Iran and perhaps Saudi Arabia, and convert it into "World War IV," the war of their dreams, a war of civilizations, an Armageddon, with America and Israel on one side and Islam on the other.

Well, why don't they tell us what they really think? At least both men agree that war is "a great clarifier." When Buchanan accuses the neocons of fealty to "a nation not their own," and then roundly names that nation as the state of Israel, he may or may not be attempting an ironic stroke: Israel either is or is not the country which his American opponents feel to be their "own." He also knows very well from experience what the neocons will say, or at the very least imply, about this choice of terms. Here, I will select David Brooks of The New York Times, who is counted as a moderate among the neocon columnists. Earlier this year, he derided the conspiratorial overuse of the term, and wrote that "con is short for 'conservative' and neo short for 'Jewish.'" He later took this back. "I realized that when you try to be funny and also use an ethnic term," he tells me, "you always introduce an imprecision or a generalization. So I withdrew it. But I wouldn't withdraw it where Buchanan was concerned. His notorious opinion of the Jews has now melded with an ideological worldview."

You could write all this up as a tussle over The Passion of the Christ, detested by Jewish reviewers, hailed by Pat Buchanan and conservative nativist Christians of all denominations, and now packing in Muslim audiences in the Middle East and adding to an already intoxicated climate of loathing for a Judaized America. But that—though it is a tempting metaphorical subtext—would (almost) be wrong. So it has come to this. In the midst of a real war, with American troops desperately engaged in everything from nation building to torture, American conservatives are having a civil war. If that sounds improbable or even surprising, it should not. This civil war has been going on for a very long time. Buchanan did not mention "neo-Jacobins" for nothing. There were always those Jeffersonian radicals, many of them religious agnostics, who thought that the American Revolution, like the French one, had a political mission in the world. And there were always those who thought that the new American republic should tend to business at home and concentrate on the family, the hearthstone, and the pulpit. More recently, the paleocons have upped this historically isolationist rhetoric against the neocons, and referred to them sardonically as "Trotskyites" who support a global policy of "permanent revolution." In this comparison, David Frum and William Kristol and Paul Wolfowitz resemble not just Robespierre and his bloodstained knitting crones, but a fiery Communist internationalist who was, shall we say, not a conspicuous Gentile. This is playing the polemical game for quite high stakes.

I should probably declare my interest here, as a part-Jewish recovered ex-Trotskyist who strongly favors regime change. But I think I understand the conservative as well as the liberal objection to interventionism. It is finer as well as safer to have a republic. It can be nasty as well as risky to have an empire. Empire leads to big government, vast military budgets, and intrusive state intervention in the private lives of citizens. Americans are no good at empire anyway, being isolationist in mentality, predominantly Christian in character, and impatient with long and costly commitments. And, especially as regards the Islamic world, we are doomed from the start by being overdependent on other peoples' oil fields, to say nothing of having Israel's loudly rattling can tied to our tail.

It is not only the paleoconservatives who now take some version of this view. At the April gathering hosted by the Heritage Foundation, a get-together involving some 600 conservative think-tankers, Ed Crane, founder of the libertarian Cato Institute, gave a major speech which took the form of a strident attack on the neoconservatives. One of his colleagues, Christopher Preble, has refounded the Anti-Imperialist League, a letterhead originally set up by Mark Twain and others to oppose the 1898 Spanish-American War and the American annexation of Cuba, Guam, Puerto Rico, and the Philippines. (This imperial or "expansionist" policy had been adopted by President William McKinley, whose successful domestic Republicanism is well known to be one of Karl Rove's favorite historical analogies.)

In Bob Woodward's Plan of Attack I was interested to find something which seems to have escaped the reviewers but which I happen to know to be true. Michael Gerson is the president's fluent and subtle chief speechwriter as well as the best-known evangelical Christian on the White House staff. He had scant relish for writing pro-war speeches. There are more believing-Christian anti-warriors than most anti-war propaganda is willing to notice. (And I will add that, during the time that Gerson was believed to be gung-ho on the war, I was told by several anti-war right-wingers that he was actually a convert from Judaism—which he is not.)

Even more common than the paleo or libertarian, especially since April, is the remorseful conservative who says that he or she gave the Bush administration the benefit of the doubt. "I guess I always trusted them to know something about Iraq that I didn't." With a five-spot for every time I've heard this from regular Republicans, I might not be wealthy in country-club terms but would be well on my way to becoming rich. The most repellent statement made so far was by Stephen Moore, who presides over the Club for Growth, a bunch of high-tab donors to Bush's reelection campaign. "We don't want to put our troops into a situation that is increasingly a public-relations problem for the president," observed this deep thinker. "No one wants body bags coming home in September and October." The corollary of such philistine callousness is presumably that a few body bags will be O.K. up until the convention season. But no later, thanks all the same.

And there is a reason for this combination of ghoulishness and credulity, according to Grover Norquist, who is one of the main G.O.R brokers in Washington: "The neocon ascendancy in foreign policy is because they care about it, and cared," he says. "With a volunteer army, no draft, superpower status, and a lot of trust in the president and indifference to the rest of the world, mainstream Republicans tended to leave it to those who minded." Once a Reaganite and a Cold War foreign-policy militant, Norquist has taken no very distinct view on the "War on Terror," except to oppose some of the more egregious provisions of the Patriot Act and to point out dryly that large commitments have a tendency to lead to high taxation. (He's also credited with rounding up a lot of Muslim-American votes for Bush last time.) He slightly scoffs at the magazine war between William Kristol's neocon Weekly Standard and Pat Buchanan's American Conservative: "Here are two magazines with circulations of 65,000, tops, with a lot of those copies given away," he tells me. "Buchanan has more or less left the Republican Party. As for Kristol—look at the record. He wanted Cohn Powell to be president. He wanted Lamar Alexander to be president. He wanted John McCain to be president. He wanted a confrontation with China in the early days of the Bush administration, and then he wanted an invasion of Iraq. O.K.—I'll give you that he got Iraq."

Indeed, the chief defense offered by neocons these days is a meekly sarcastic account of their own weakness. The famous neocon educational organization chaired by Kristol, "Project for the New American Century," which called for a more forward and interventionist policy in the Middle East, has a staff of exactly four. Trotskyism, which once did appeal to some of the older neocons, such as Kristol's father, Irving, is a muted voice, to say the least, among today's right-wingers. There are as many senior people of Arab descent (Spencer Abraham) on Bush's team as there are Jews (Josh Bolten). So what's all this about a ruthless and secret Zionist cabal running the show? The recent pro-war book An End to Evil, by David Frum and Richard Perle, opens with an invocation taken straight from Thomas Paine's revolutionary polemic The American Crisis. Those pesky Jeffersonians again ... worming their way into the highest circles.

Behind this vitriolic rivalry are two ancestral questions, one ancient and one modem. The last truly fierce debate on American intervention and empire took place in the Roosevelt years. Those who opposed a confrontation with the German and Italian and Japanese empires, like Charles Lindbergh, Joseph Kennedy, and Father Coughlin, spoke as patriots who wanted to "keep America out of war." But they were also suspected, not without evidence, of being privately sympathetic to the aims of Fascism. And, even after Pearl Harbor seemed to have decided the question, many of them went to their graves believing that F.D.R. had somehow fixed up that provocation so as to accrue war-making powers and continue his socialistic, big-spending New Deal. Truman's inheritance of this policy— a worldwide postwar crusade against Communism—left more conservatives cold than we usually remember. Those Republicans represented by Robert Taft openly did not care who ran Europe—as long as America could stay out of it. It was quite common on the mainstream right, as recently as Bob Dole's notorious 1976 remarks on the subject, to hear America's overseas dead described as victims of "Democrat wars. Eventually the stench of the Final Solution, and the smoke from the Budapest rising against Stalinism, coupled with large-scale immigration by refugees fleeing both Nazism and Communism, changed the American culture forever. The tradition represented by Pat Buchanan still slightly doubts the official evidence about Pearl Harbor and about the Holocaust, and even the slightest doubt on these matters is enough to inflame his foes. They, and he, have long memories. History, to them, is right here and right now. They do not dwell in "the United States of Amnesia," as described by Gore Vidal—a man who has been both a right and left isolationist in his day. One faction thinks that you still can "keep America out of war." The other believes that, whatever you may wish, the fanatical or totalitarian enemy can ensure that war will come. Again, I must say that I pity those who hold the first view ...

You could write all this up as a tussle over The Passion of the Christ.

The second episode, already forgotten even though it occurred only yesterday, concerns the abrupt departure of Trent Lott as Senate majority leader in late 2002. Having warmly praised the Dixie record of the old segregationist and paternity-suit miscegenation artist Strom Thurmond, Lott sweatily resorted to an appearance on Black Entertainment Television to promise support for affirmative-action programs if he was allowed to stay on. For a number of neocon pundits, that was it. You can perhaps fail to be color-blind once, but not twice—or not twice in the same news cycle. More traditional reactionaries like Pat Buchanan, Robert Novak, and Sean Hannity stuck up for Lott briefly before the White House calmly and calculatedly dumped him. But here was another case where ex-liberals and ex-Democrats, who had traditionally supported the New Deal and the civil-rights movement, came up against paleoconservatives like Buchanan, who think that the United States has been going to hell on a sled at least since the 1960s, if not the 1930s. The article of his from which I quoted earlier is entitled "Going Back Where They Came From." It's not the only attack from the old right that describes the neocons as Johnny-come-latelies: chancers who had changed their party allegiance just in time to catch the Reagan tide, but who remained liberals and cosmopolitans under the skin. Indeed, William Kristol has proved Buchanan's point, by telling The New York Times that, if pushed, by which he clearly meant "in any case," he would prefer an alliance with liberal hawks to one with anti-war Republicans.

Thus, however much and however stupidly the analogy may be overstated, the Iraq war is indeed like the Vietnam War in one respect. The Vietnam War was proposed by a Democratic president, but got an easy Republican majority in Congress; the Iraq war (in 1991 and also in 2003, if you think the war against Saddam ever stopped) is almost a reverse consensus, allowing only a slightly easier "out" to the members of the party not in power. John Kerry is in the painful process of discovering the truth of this for the second time in his pro-war/antiwar career. The latest conflict offers a very stark illumination of long and deep, and in some cases suppurating, divisions within American society. It has riven both parties from stem to stem, and would have done so even more if—which is quite thinkable—it had been launched by a Democratic presidency. It may be a war waged by generally conservative tacticians, but it is a project designed by internationalist and liberal minds. One should be scrupulous about mentioning the large number of Jews among this last faction. I don't say this for reasons of taste or discretion. Many of the neoconservatives—Jeane Kirkpatrick, William Bennett, James Woolsey, Michael Novak—are not Jews. The original political patron of the neocon movement, Senator Henry Jackson, was a mildly liberal anti-Soviet and antiKissinger Democrat. The term "neoconservative" itself was coined, almost affectionately, by the late hero of American socialism Michael Harrington, who had known most of its original adherents personally. (I distinctly suspect that Pat Buchanan knows this, while George Bush does not.) The last time all or most of the neocons agreed on something, and helped argue the White House into a war, was when they demanded a stand against Slobodan Milošević in the Balkans, and a defense of Europe's Muslims against mass deportation and mass murder. This policy was opposed by, among many others, Pat Buchanan and Ariel Sharon. We shall go through many more excruciating ironies and contradictions before the Mesopotamian war is over one way or another, but it appears sure that we cannot escape some very barbed and vicious disputations about "Who lost Iraq?" or "Who got us into this?," and the great point of interest is that some leading spokesmen of both camps are certain to be from the right.