In December, Richard Gephardt was at 6 percent in the Iowa polls. On Monday, he won the Iowa caucuses with 31 percent. In the interim, he found a message. The message was that America's problems are caused by others. Most prominent among these others, as explicated in Gephardt's now famous Iowa TV commercials, are South Koreans. Gephardt admits that America's trade problems are 80 percent self-induced. But he is the candidate of the other 20 percent. Posing as a trade Rambo, he promises that if those selfish Koreans, who so tax and tariff the Chrysler K-car, do not bend to his will, President Gephardt will make Hyundais cost $48,000.

Now that Paul Kennedy's "Rise and Fall of the Great Powers" has made the best-seller list, it is fashionable to speak of American decline. Gephardt has now offered the first truly solid piece of evidence for that theory. It is one thing to rouse a great country to the challenge of a Germany, a Russia or a Japan. But South Korea? When a presidential candidate goes to the head of the pack by beating up on a dwarf -- an American protectorate whose entire GNP amounts to less than two-thirds of America's annual restaurant bill -- you know that we are indeed becoming a little people.

Gephardt did not, however, content himself with scapegoating foreigners. His railing took particular aim at "the Establishment" here at home, the ubiquitous "they," who together with clever people abroad (as it happens, of different color) are stealing America from "us." To call this message populism is to be generous. It is, in fact, the politics of resentment.

Iowa's role in the march of the presidential campaign is to sort out themes. (And, of course, to winnow out candidates: Babbitt, Hart, Haig and du Pont are gone; Simon going.) Where Gephardt offered resentment, Michael Dukakis offered compassion. Gephardt's Iowa stump speech featured a line that practically defines resentment politics: "We've been too good." Dukakis's message, on the other hand, was that we've not been good enough. Dukakis blanketed Iowa with a pair of reproving TV ads: one showed pictures of the homeless, the other of war-torn Central America. Dukakis declared his compassion for both. He promised, for starters, to "stop the shooting war in Nicaragua and start the war against poverty and injustice and exploitation throughout Latin America."

There are three things that can be said so far about Dukakis's compassion.

(1) It is probably genuine. The notion that America's role in the world is to eliminate its misery (since in a world without misery, America would no longer have foreign policy problems) is an idea of such Olympian naivete' and of such irrelevance to the actual nature of foreign affairs that it could not be ventured if it were not deeply felt.

(2) It is expansive. Dukakis' "we can do better" message tries to evoke the compassionate liberalism of the '60s. But even Lyndon Johnson, the most ambitious of '60s liberals, took care to declare war on American poverty, over which he at least had sovereign jurisdiction. Dukakis promises a hemispheric assault on poverty, no doubt drawing on America's success in wiping out the scourge at home.

(3) It did not play too well in Iowa. In fact, it did poorly enough to put a dent in another of today's fashionable theories, Arthur Schlesinger's idea of political cycles. Schlesinger holds that the crass, corrupt, greedy '80s must, like the '20s and '50s, yield to the logic of the 30-year cycle and usher in a caring, compassionate, socially conscious era reminiscent of the '30s and the '60s. Well, the results from Iowa are in. Gephardt bashed up Koreans for bringing down our standard of living by selling us cheap cars. Dukakis promised to open his heart and the U.S. Treasury to the homeless and the oppressed. Resentment went up against compassion and resentment won by nine points.

On the Republican side too, Iowa offered little encouragement for those awaiting the return of American high-mindedness. The big winner was Pat Robertson, whose insipid, saccharine smile does not hide his message of resentment. His is not economic resentment a` la Gephardt. It is cultural. Gephardt appeals to those who feel that "they" are stealing our jobs. Robertson appeals to those who feel that "they" are stealing our values.

Robertson says he is fighting not just a Republican Establishment that tries to rob him of one election (Hawaii) after another (Michigan), but a bicoastal conspiracy against heartland American values. His is a revolt of the culturally disenfranchised against a national ethos that has become progressively more secular and liberal. Never mind that this historical tendency is universal in the developed world and, in America, older than the republic. Robertson has identified the villains (which is how you give grievance political form): a cultural Establishment that has rent the family, corrupted our morals and sent God home from school.

When such are the stakes, it follows that this is "not an election but a fight for America." That is Gephardt speaking, but he speaks for Robertson too, for anyone whose campaign is built on a grievance against "them," the ineffable, execrable, alien other. "Them": as in "Send them a message," the slogan of the greatest living practitioner of the politics of resentment, George Wallace.