Why did President-elect Ronald Reagan suddenly break his silence on the hostage issue, calling the Iranians "criminals" and denouncing the payment of "ransom for people who have been kidnapped by barbarians"?

It is an interesting question at this time of transition from one year (and one president) to the next, when tradition requires piercing predictions of the future and solemn reflections on the past.

Does this portend a much tougher American line three weeks from now, when in all probability the hostage problem will be President Reagan's to solve? Does it mean he will revert to his initial position when the hostages were first seized, and fix deadlines, threaten unspecified reprisals, break off negotiations, mine the ports?

Perhaps. But my reflections on the history of the hostage issue lead me to predict that any breakthrough on the hostages will not be as a result of a new Reagan "hard line." Conceivably, it could come out of an uncharacteristic consensus among Iranian authorities to do business with President Carter, rather than wait for the unknown of Ronald Reagan. More likely, it will come only after some sort of internal upheavel in Iran leading to the formation of a government strong enough to conduct coherent negotiations.

The lesson of 1980 is that there has not been such a government -- and that there isn't one now. The president-elect's supporters would argue that firm new American "leadership" may be enough to give pause to the Iranian authorities. But my hunch is that the Reagan administration will discover, as the Carter crowd has learned many times, that Tehran's anarchic revolutionary government does not lend itself to traditional forms of diplomacy and/or force.

Something else the Reagan administration may discover, if the experts I've talked to are right, is that the mob-rule regime of Ayatollah Khomeini is, in the words of one veteran diplomat recently returned from the Persian Gulf, "disintegrating and close to collapse." The combination of the war with Iraq, economic sanctions and the destruction of crucial refineries and pipelines has shut off supplies of fuel for heating and cooking and crippled the economy. "There's rationing, real hunger, real cold, in the north," this authority reports. "Except for the government and the small shops, unemployment is almost total."

Ironically, some experts believe the Iraqi attack actually bought the Khomeini government extra time, by uniting disparate elements against a common enemy. But one has only to note the on-again/off-again, hot-and-cold course of the hostage talks to know that the power-struggling is intense and unresolved, that there are moderates eager to be rid of what they themselves now call "the hostage problem," that there are fanatic religious elements beyond the reach of reason and that Ayatollah Khomeini is only very loosely in charge.

"That government can't survive the winter," says one American with long experience in Iranian affairs and good connections to observers on the scene. By spring, he's confident, some combination of the military and the moderates will make their move.

Now, just when this might happen, or what form it might take, or what sort of Iran would emerge if a counterrevolution does materialize, is impossible to predict. The point is that until it does happen, it is equally impossible to calculate safely the consequenses of some abrupt shift to a "hard line" in the hope of influencing the actions of what is now loosely called the "Iranian government."

So what does it profit Ronald Reagan to seem to be scorning the eleventh-hour negotiating efforts of the Carter administration and hinting at a whole new, and much tougher, approach when his turn comes?

The explanation may be nothing more than the one he gave -- he was "just telling how I felt -- but if [the Iranians] get a message out of it that they shouldn't be waiting for me, I'd be very happy."

Interestingly, the Carter administration accepts that explanation and, according to one official, actually welcomed the president-elect's strong words. No orchestration, it's agreed, was involved. But the Carter negotiators, I'm told, saw no great harm in Reagan's outbursts about paying "ransom" to "criminals," "kidnappers" and "barbarians" even as they were laboring with Algerian intermediaries to prepare a U.S. response to the latest, supposedly final and plainly excessive Iranian settlement terms.

"If Reagan can persuade the Iranians that he'd be tougher than us, just maybe we could get an agreement before Inauguration Day," says one, who believes that was, in fact, Reagan's principal aim. The question is whether today's sharp words should also be taken as an accurate preview of how Reagan would handle the hostage problem, once in office. Given the state of Iranian internal affairs, that is not something that can be safely assumed.