Step right up, folks. For a special, one-time-only, introductory price, you have been invited by the promoters of a new quarterly magazine, The National Interest, to be "Present at the Creation" of a "fundamentally" new and pretty nearly foolproof foreign policy for America. The invitation's wording in a half-page ad in The Washington Post borrows Dean Acheson's title for his memoirs of the making of the Marshall Plan, the Atlantic Alliance and the Truman Doctrine by way of heralding a creation of comparable consequence.

But there will be a "striking" difference: "The role played yesterday by Acheson and the liberal intellectuals -- the creators of our postwar policy -- belongs today to conservative, neo-conservative, and neo-liberal thinkers. They are the ones who are starting to make our foreign policy more coherent, forceful and effective."

Well, swell. But you have only to have read Acheson's memoirs to recognize the analogy for what it is: a hype. As a commentary on the power of conservative thinking, it is also a humiliation of sorts. The big names are there: Henry Kissinger and Jeane Kirkpatrick on the advisory board; Zbigniew Brzezinski as a contributor to the first issue; Irving Kristol, one of neo-conservatism's high priests, as publisher. But you are hard put to find among the would-be creators people now actively engaged in government or well noted in their recent thinking and talking for an accommodating spirit or a common sense of how to get our foreign policy right.

Just the opposite, of course, was the case with the foreign-policy-making process of which Acheson was a part. The great postwar initiatives were created and carried out not by conceptualists shouting critiques from the sidelines but by politically pragmatic bureaucrats working within the government and with Congress.

That's why the arrival of The National Interest is less interesting as a publishing venture than it is for what this says about the performance of the Reagan administration five years after it was supposedly swept into office by a flood tide of conservative sentiment. When people of conservative bent are talking in 1985 about the need for a properly conservative foreign policy -- and claiming "they are the ones who are starting" to make policy more "coherent, forceful and effective" -- they are not saying much about the work that has gone forward on Ronald Reagan's watch.

This is all the more so when some of those identified with The National Interest have had an active hand in the making of the Reagan policies (Kirkpatrick, Assistant Secretary of Defense Richard Perle, State Department policy planner Peter Rodman). The anomaly is compounded when people such as Kissinger, Kirkpatrick and Brzezinski come together in a publication dedicated to the proposition that we have not seen in our foreign policy a sound appreciation of national interests for two decades -- and are not seeing it now.

It is as if Henry Kissinger had no hand in foreign-policy-making in the eight Nixon-Ford years, when he was first national security adviser and then secretary of state. For another four of those 20 years, Brzezinski was at the center of the Carter administration's foreign-policy-making process. For the next four, Jeane Kirkpatrick was thought to be the mirror image of Ronald Reagan's geopolitical thinking -- or was it the other way around?

If these contributors are not exactly bound together by past association or political party affiliation, what are the ties that bind them to The National Interest now? Expedient and loose, judging by the only positive policy statements to be found in the prospectus for the magazine. "We believe," the advertisement says, that "the first purpose of American foreign policy is to defend and advance the national interest of the United States."

How's that for zeroing in on problem areas? "International politics remains essentially power politics," the ad continues, adding: "The efficacy of military power remains undiminished." To the extent that efficacy means "the power to produce effects or intended results" (Webster's), where (except perhaps in Grenada) is the recent evidence to offset the lesson of Lebanon on the "efficacy" of U.S. military force?

Finally, the creators of The National Interest believe that the Soviet Union continues to pose "the greatest threat to America's interests." Once again, we are not exactly getting to the nub of what would constitute a better foreign policy. A policy devoted to the defense of "the national interest of the United States" would be greatly enriched by a reasonably precise definition of what our national interest is. And it is not until we get well into an interview with Kristol in The Post that we discover that "the point of our magazine is to help define that. . . . I don't think there is any set definition."

So there we are with this opportunity to be "present at the creation" of a whole new foreign policy whose purpose its would-be creators are not yet in a position to define.