Whatever are we to make of the week that was -- the "chills and thrills" of the final negotiations with Iran and the heart-tugging airlift of the hostages to safe haven coming together with the pyrotechnics of the Reagan inaugural and the lonely leave-taking of Jimmy Carter?

It was too much -- even for the instant historians. Some saw a triumph of patient diplomacy, others "ransom." It was a metaphor on the Carter presidency some said, a humiliation to the nation brought to conclusion not by Carter so much as by Reagan's tough talk, promising a much tougher line on every aspect of foreign policy.

Right up to the end, in other words, Jimmy Carter couldn't really win. Not even the return of the hostages, and still less his handling of the crisis during the torturous 14 1/2 months of their captivity would be looked upon favorably by history.

Well, maybe so. But a country that still can't reach much of a consensus on what to make of Vietnam (or even Watergate) is in a poor way to second-guess the judgment of history on the Carter presidency.

With the critical perspective of time, who's to say whether Carter will be remembered best for the Brezhnev kiss or the three-way symbolic handclasp with Anwar Sadat and Menachem Begin? For Afghanistan or the "normalization" of relations with Peking? For the unfinished road or the walk down Pennsylvania Avenue?

What matters now, it seems to me, is what the Reagan administration makes of the immediate realities when it comes off its inaugural high. When the Carter-versus-Reagan, hard-line-versus-soft-line, "vacillation"-versus-"consistency" rhetorical jousting no longer has any validity, what will the world look like to President Reagan from inside the Oval Office, looking out?

My guess is that it will look a lot harder to deal with in a general way than had been expected, not by any of Jimmy Carter's doing but by the nature of things. But the view from the White House may also look a little brighter as a consequence of some of Jimmy Carter's legacies.

The hostages' release is the instant case. Whatever Reagan may have said along the way about the dishonor of negotiating with "barbarians," he could hardly question the judgment of the redoubtable leader of the hostage families, Louisa Kennedy, when asked if her husband and the rest had been returned with "honor." Absolutely," she replied. "No question about that."

In any event, the tormenting crisis is not on Reagan's desk. The hostages are safe. And this frees the United States to play a hand in and around the Persian Gulf in new and perhaps more promising ways.

Clearly, American-Iranian relations will be a long time mending. It may take a change of government in Tehran, or a much more profound change of heart than can be read into the hostages' return. Iran has little immediate interest in American support in the war against Iraq -- as evidenced by the fact that military spare parts that had been part of the frozen assets were not a sticking point in the settlement.

But the Iran-Iraq war, now bogged down by winter weather, still poses a potential threat to Persian Gulf oil supplies far more serious than the Soviet troops (also bogged down) in Afghanistan. The possibility of an American role of some sort in peacemaking is obviously enhanced by the removal of the hostage issue.

In the Arab-Israeli conflict (related at least geographically), the Reagan administration also may discover that Jimmy Carter's Camp David framework, however controversial, remains the only feasible starting point for any new American initiative. Secretary of State Alexander Haig indicated as much in his confirmation hearings.

Even before assuming office, the Reagan brain trust had begun to reconcile itself to the logic of Carter's agreements to "normalize" relations with the People's Republic of China. The new president is unlikely to threaten that relationship, whatever he does in office to ease some of the anxieties and bitterness of his friends on Taiwan.

Having accepted, grudgingly, the Panama Canal treaties, President Reagan is also likely to discover, from the inside, how much good will they engendered in important circles in Latin America in general, and Central America in particular.

In the crisis spot of the moment, El Salvador, the recent resumption of American military aid, including "lethal" items, to deal with a growing leftist insurgency is entirely in keeping with the Reagan administration's likely policy.

In other areas -- Europe, defense spending, arms control -- president Reagan is almost certainly going to find himself building on Carter foundations more often than he will find himself building something altogether new. In short, while we await history's verdict on the Carter presidency, Ronald Reagan's verdict, in actual practice, may be more congenial than his campaign challenges might have led us to suppose.