Throughout his political career, Ronald Reagan has been the master of appropriate symbolism, of the dramatic action that captures public opinion at a critical moment.

Apprehension of the hijackers of the Achille Lauro, for all the diplomatic distress it has caused, perfectly demonstrates the Reagan touch. At a time when Americans hungered for an effective response to terrorism, the combination of a Palestine Liberation Organization blunder and a skillful U.S. military response gave Reagan the victory he had been seeking.

But this victory, while contributing to another spurt in Reagan's popularity, has disappointed conservatives in and out of the administration. Defense Secretary Caspar W. Weinberger was worried from the outset about the strain it would cause in U.S.-Egyptian relations. Conservative activists have used the incident to deplore what they see as administration timidity in the face of terrorism.

It is certainly true that few politicians have talked as much about terrorism and done as little as Reagan. On the conservative banquet circuit in the 1960s, Reagan often told how Secretary of State John Hay, at the instruction of President Theodore Roosevelt, had responded to the capture of U.S. citizen Ion Perdicaris by a Moroccan bandit named Raisuli. A telegram sent by Hay to the U.S. consul general in Morocco demanded "Perdicaris alive or Raisuli dead."

Like many Reagan warnings, this 1904 telegram had another message not shared with Roosevelt's campaign audiences. The unpublished portion warned the consul general not to use force without specific instructions. But the recounting of the warning inevitably produced a frenzied audience response, ratifying the insight of Hay, who wrote, "It is curious how a concise impropriety hits the public."

Reagan specializes in such concise improprieties. In his 1980 campaign, when Americans felt humiliated by the Iranian hostage crisis, Reagan repeated the Perdicaris story. Greeting these freed American hostages at the White House on Jan. 27, 1981, a week after his inauguration, Reagan said, "Let terrorists be aware that when the rules of international behavior are violated, our policy will be one of swift and effective retribution."

Reagan repeated this warning in varied forms when 241 U.S. servicemen were killed by a suicide bomber at the Marine headquarters in Beirut in 1983 and when hijackers captured American hostages and murdered a Navy diver on TWA Flight 847 last June.

The obstacle to Reagan's vow of "swift and effective retribution" has been Reagan's standard for appropriate retaliation. It is a moral standard, surprising to some of Reagan's critics on both the right and left even though eloquently expressed by the president during the TWA crisis and again on the day he ordered capture of the Achille Lauro hijackers. His view is that to harm innocent civilians while retaliating against terrorists is itself an act of terrorism.

This was Reagan's view last June when political advisers wanted him to retaliate for a cafe bombing in El Salvador that killed off-duty U.S. Marines. It was his view this month when he endorsed Secretary of State George P. Shultz's criticism of an Israeli raid on PLO headquarters that killed a score or more of Tunisian policemen and civilians. Reagan does not intend to adopt "an Israeli standard of proportionality," said a senior official who would like him to do just that.

The capture of the Achille Lauro hijackers did not resolve the dilemma posed by the conflict between Reagan's rhetoric and his scruples. No retaliation was involved, and no precedent was set, except perhaps for the interception of bungling hijackers who try to flee the scene of a brutal crime.

In the fifth year of his presidency, Reagan is still struggling to find an appropriate policy for responding to terrorism. But he has done something more important than that and more significant than any "concise impropriety" he has ever uttered. He has set a civilized standard for appropriate retaliation. It is no small thing.

Reaganism of the Week: Campaigning for the pending deficit reduction bill in Milwaukee last Tuesday, the president said, "This far-sighted legislation puts in place a fair, enforceable method of reducing the budget deficits by equal amounts each year, mandating a balanced budget by the end of 1980 -- or 1990. I'm sorry. 1980's kind of Freudian with me; something happened then, too."