Democrats might need spunk more than unity.

LIBERALS have been suffering from conservative envy for several years now. Oh, they don t envy us our evil ways, our penchant for extreme cruelty or the fact that we smell like cabbage. They envy us our toys and success.

The liberal Center for American Progress was founded explicitly to be the left's answer to the conservative Heritage Foundation. The lefty radio network, "Air America," was launched to copy the success of Rush Limbaugh & Co. Today, deep-pocketed liberals are scrambling to copy conservative foundations, even though liberal foundations have always had more money.

Most conservatives I know snicker at all this. It's not that talk radio, think tanks and foundations haven't been essential to the rise of American conservatism in the last five decades. But liberals are emphasizing hardware because they don't want to question the validity of their very outdated software.

Look, conservatives would love to switch places with liberals. We'd get the universities, Hollywood, the Rockefeller, Ford, Carnegie and Pew Foundations, the Sierra Club, Greenpeace, The New York Times, National Public Radio, Time, Newsweek, The New Yorker, CBS, including "60 Minutes" and Dan Rather's thousand-fingers massage chair, and so forth. Liberals, meanwhile, would get the Washington Times and Fox News, along with a few conservative foundations.

And that sort of makes the point: Not only does the left have better stuff, but even if that weren't the case, the left's problem isn't a lack of mechanisms to "get their message out." Megaphones matter, but not as much as what you say into them.

If liberals really want to emulate conservative successes, I have some advice for them: Get into some big, honking arguments--not with conservatives, but with each other. The history of the conservative movement's successes has been the history of intellectual donnybrooks--between libertarians and traditionalists, hawks and isolationists, so-called neocons and so-called paleocons, less-filling versus tastes great. Liberals would be smart to copy that and stop worrying how to mimic our direct mail strategies.

Liberals have a tendency to mistake political tactics for political principles, and vice versa. Exhibit A is the left's fascination with "unity." Unity is often useful in politics, but it's often a handicap if you haven't figured out what to be unified about. Just as the Socratic method leads to wisdom, big fights not only illuminate big ideas, but they force people to become invested in them. Unfortunately, liberals define diversity by skin color and sex, not by ideas. That makes it difficult to have really good arguments.

Of course there are arguments on the left and there are individual liberals with deep-seated convictions and principles. But most of the arguments are about how to "build a movement" or how to win elections, not about what liberalism is. Even the "Get out of Iraq now!" demands from the base of the Democratic Party aren't grounded in anything like a coherent foreign policy. Ten years ago liberals championed nation-building. Now they call it imperialism because George W. Bush is doing it.

Bill Clinton was the only Democratic president elected to two terms since Franklin Roosevelt. One of the reasons for his success was that he was willing to pick fights with his own party. One can argue about the sincerity of some of those fights. But we remember the Sista Souljah moment for a reason.

Right now Washington is marveling at how the Democratic Party has simultaneously made the Iraq war the central and defining political issue of the decade while at the same time having no clue what it is they want to do about it. Worse, it's looking increasingly like the Democrats' position on the war is based largely on the polls, not principles.

One of the most important events in the rise of conservatism was the 1978 "Firing Line" debate over U.S. control of the Panama Canal. William F. Buckley favored giving it up. The governor of California, Ronald Reagan, favored keeping it. Reagan's side lost the argument, in Congress at least, but conservatives once again demonstrated our willingness to duke it out on such issues. And Reagan's career hardly suffered. If liberals were smart, they'd do something similar. Have Joe Lieberman debate Nancy Pelosi, or John Murtha. Make liberals get past their passion and explore what they think. My guess is it would be good for liberalism in the long run--and even better for America.

Jonah Goldberg is editor at large of National Review Online. Mark Lacter's weekly comment begins on page 15.