Ronald Reagan's candidacy illustrates perfectly the dilemma raised by the Iran crisis: how to be tough without going off the deep end.

Reagan certainly has no trouble acting tough. He's been there for years and can rightly say that the rest of the country is finally catching up with him -- or catching up with his slogans, or with his ideology. The ayatollah, making his move on the eve of Reagan's presidential announcement, could not have helped him more. The candidate did not even have to cite the kidnapping in order to capitalize on it.

To be sure, even in addressing the Iran issue at his news conference here the next day, Reagan -- after saying he "completely supported" the president -- did not go beyond a kind of indirect packaged critique of Carter for letting down the shah and "appeasing" the ayatollah and, in general, for believing "that if we can convince them we're nice people, they'll warm up to us."

That was smart. It is foolish and unnecessary to tell Carter how to play out the crisis tactically. Reagan, moreover, will almost certainly fare better by simply trying to project that he could handle the tough ones. It would spoil the effect if he were to try to spell out the details. Indeed, diplomatically as well as politically, a case can be made for keeping things somewhat fuzzy, as Reagan -- by design or instinct -- seems to do.

Yet Reagan is no Eisenhower, whose indirection and seeming unsophistication concealed what many of his erstwhile critics have since come to admire as a talent for maintaining international calm and political control. Reagan comes off as low-key, mature and decent. But he is no national hero, and no general. He is an ideologue. If he is not himself an extreme person, he appeals to the extreme.

Look at his announcement speech: "Though we should leave no initiative untried in our pursuit of peace, we must be clear-voiced in our resolve to resist any unpeaceful act wherever it may occur. Negotiation with the Soviet Union must never become appeasement. . . . Since the Second World War we have spent large amounts of money and much of our time protecting and defending freedom all over the world. We must continue this, for if we do not accept the responsibilities of leadership, who will? And if no one will, how will we survive?"

Resist any unpeaceful act wherever it may occur . . . defending freedom all over the world: it is impossible to read those words without picking up the echo of John Kennedy's inaugural promise to "pay any price, bear any burden" for liberty, and without wondering how any politician could speak those words without recoiling from the folly of making open-ended commitments to universal ideals.

That Reagan could so casually evoke the most discredited aspect of the Kennedy legacy suggests a rather mind-bending triumph of ideology over good sense. The ideology is made explicit elsewhere in the Reagan announcement speech. It is the myth of American uniqueness: for Americans, and only for Americans, whether in their claim on resources or their standard of living or their freedom of maneuver in the international arena, don't count; we can have and do it all.

There is no denying, however, that the Iran crisis has brought to a boil, across most of the political spectrum, the popular feelings that seem to validate Reagan's no-limits appeal. The frustration felt by so many people -- people including people otherwise untroubled by international turbulence and people who know perfectly well that turbulence is the rule -- is apparently ripe for political picking.

Yet it is too early to mark Reagan down as irredeemable. This is not to say he does not believe what he says. Surely he does. But in the very same announcement speech he came out with a major proposal reflecting all the intelligence and restraint otherwise so conspicously absent. I refer to his idea, to which he devoted a full two of his four pages on foreign policy, for a North American "accord" with Mexico and Canada. Expanding on it the next day, he said that Mexico needs a "safety valve" for its excess population: "We have torecognize the other man's problems."

I take all this to mean that the times have unhinged us, but not completely.

We may not have found the formula -- the right mix of self-assertiveness on the one hand and readiness to go with the flow on the other -- to deal with our uncertain world, but at least we're looking for it.