Does a president have a right to tell a lie? That question has probably been kicked around in this country ever since George Washington.

It is very much with us these days in connection with the way the Reagan administration is presenting what it is doing (or not doing) in Central America, and to what end. Herewith, an effort to complicate the issue in the interest of clarity.

We will get nowhere without first stipulating that, while circumstances alter almost any case you can think of, the president has an inherent right--perhaps even an obligation in particular situations--to deceive. Deception is not only a legitimate tactic in war, it is critical to what is called deterrence: the maneuverings and the posturings, the arms buildups or the positioning of forces for the purpose of facing down an adversary in the interests of avoiding a war.

Whether we are talking about moving the battleship New Jersey to the Central American coast or massing American troops for military exercises in Honduras or installing Pershing IIs in Western Europe, a certain ambiguity of purpose is, as John Foster Dulles used to say, "a necessary art." So I think columnist Edwin M. Yoder Jr. was absolutely right (op-ed, Aug. 3) in the defense of a little presidential deception.

But the justification for deception requires some weighing of the service rendered to national security against the damage done to cherished values and trusted institutions. Ham-handed deception doesn't meet the test; the operative word in Dulles' doctrine is "art."

So I was less bothered than Yoder by the silliness of the questions at the president's last press conference or by their reflection of overwrought anxiety. Surely this had something to do with: (a) the president's penchant for reckless and bellicose formulations of his foreign policy, and (b) his soft and sometimes silly answers, presumably calculated as an antidote for (a).

This is not a game to be played one way on one day and another way the next. You cannot rush to reassure the American public that nothing out of the ordinary is going on in Central America, while American forces are piling into the area, and not rob what might otherwise be a legitimate exercise in psychological warfare of a good part of its desired effect.

What goes for "gunboat diplomacy" applies to covert activity. Assuming you think it is okay for the CIA to be working in a clandestine way to overthrow the Nicaraguan government--with all the necessary safeguards of congressional oversight having been observed --it follows that the president cannot say so, cannot openly admit to an act of war and a violation of treaty obligations.

But "covert" does have a meaning; it means keeping quiet. Thus, it is pointless for the president to be hiding behind the sanctity of "covertness" while his own men are up on Capitol Hill openly lobbying for publicly appropriated funds to finance "covert" support of revolutionary forces in Nicaragua whose openly stated purpose is to overthrow the government. This has nothing to do with the president's right to deceive; the CIA operation in Nicaragua lost all its deception long ago.

Correctly read, President Eisenhower's handling of the U2 incident in 1960 offers a useful lesson--but not if it is read as a case of excessive presidential honesty. Actually, the problem was operational; the mission was spoiled by its own success. For several years the U2s had overflown the Soviet Union at altitudes comfortably out of reach of Soviet air defenses. According to officials I talked to at the time, the CIA had simply become complacent. It had come to believe that no cover story was needed in case of a mishap.

So there was, in the jargon of the Senate hearings on intelligence, no "plausible deniability." The Soviets had the pilot, alive. They had the wreckage of the aircraft on display. The quick U.S. denial was as quickly proved implausible. Eisenhower thereupon told the truth. He had no choice. Had there been a cover story ("One of the pilots lost his bearings, or his mind, and wandered over the Soviet Union on a routine weather reconnaissance flight over Turkey," let's say), Eisenhower would have been right to tell it by way of saving face all around.

What is really giving Ronald Reagan trouble in Central America is not that kind of lie. It is that part of the so-called Vietnam syndrome deriving from the way in which the United States went to war in Vietnam: step by furtive step, while all the time insisting that this was not its intent, until the deception was no longer tenable.

Here again, the issue isn't whether the president is obliged to tell the truth, the whole truth and nothing but. It has to do with squandering the public confidence and support essential for successful conduct of the war. That, surely, was a case where circumstances circumscribed the presidential freedom to deceive. Comparable circumstances are at work in the conduct of U.S. policy in Central America today, with one big difference: once burned, Americans have at least some right to be twice-shy.