IT IS A BLESSING that the Ayatollah Khomeini has become so well known that the media need not introduce him each time they mention him. Otherwise one could foresee serious difficulties. He is hardly a man of the left, but the right-wing label does not fit him very well either. Neither a radical nor a conservative, revolutionary in some respects, reactionary in others, he is certainly no "dove." But then he is not against the SALT II treaty nor a follower of Mr. Begin, and so cannot possibly be called a "hawk" or a "hardliner." Some commentators called him a "liberal" when he was still in exile, and even during the first weeks of sanguine optimism after the overthrow of the shah. But this now seems as appropriate as calling him a "neoconservative."

The shah, on the other hand, was a tyrant, and hence a right-winger and a conservative. True, he was also a modernizer; his position regarding women's role in society was more liberal than Khomenini's, as was his attitude toward homosexuality, toward relations between Islam and state, and other issues. But all this does not make the shah a "liberal," for our views on these issues are, of course, ethnocentric and should not be transferred to other cultures.

"Fascism" in contemporary parlance is used widely and indiscriminately not only in reference to persons and parties that belong to the past, but also in current controversy. Thus the military regimes in Chile and Greece have been described as fascist; so was Portugal under Salazar and of course Iran under the shah and present-day South Africa.

But on the other hand, fascist tendencies and features have been detected in many Third World countries and even in the communist bloc. For the Chinese, the Soviet Union is not only an imperialist power aiming at world hegemony, but also a country ruled by a "fascist clique." Soviet spokesmen have retaliated in kind about fascism in Peking.

For years the Syrian Ba'ath leaders used to denounce their Iraqi Ba'ath comrades as fascists, and vice versa. Qaddafi and Khomeini have been called "clerico-fascist," Israel has been attacked by the PLO and other Palestinian organizations as fascist, and Israel has attacked the "fascist Palestinian terrorists and murderers." Some members of the New Left in the 1960s alleged that they lived in a fascist country called "Amerika." Indonesia has been described as fascist and so were both Koreas; the Vietnamese called the Pol Pot regime fascist and vice versa.

Only a very few countries, such as Denmark, Switzerland and perhaps New Zealand, have escaped the fascist label altogether. But if one looked hard enough one would probably discover some individuals even in these countries eager to correct this oversight, pointing to certain "fascist" tendencies in Switzerland and Denmark.

Many errors of truth, Spinoza once wrote, consist merely in the application of the wrong names to things. Terms such as "conservative" and "liberal," "right wing" and "leftist," radical" and "reactionary" may be of some use, within limits, in debates on domestic issues. But in foreign affairs and also usually in defense they are a source of endless confusion (and worse), simply because the great majority of foreign countries, political movements and leaders with whom we are dealing in the contemporary world do not fit into these categories.

Once upon a time it was argued that attitudes toward the Soviet Union were the decisive test: Liberals were sympathetic (or at least not too critical), conservatives were hostile. But a great deal of water has flown down the Moskva since 1917, and if the test ever made sense (which is doubtful), it is now perfectly nonsensical. Whatever its achievements, Soviet society is not liberal. Some of its features attract conservatives, but then it is not conservative either. The most bitter attacks against the Soviet Union have emanated from other communist states and movements. Is Peking to the left or to the right of Moscow? Was the Pol pot regime more or less progressive (or radical) than the People's Republic of Vietnam? Are Albania and North Korea left-wing?

It has been mentioned that since the shah was "conservative," Khomeini, his chief foe, almost automatically became a "liberal" or, at the least, a liberalizing influence. The same is true with regard to the late Boumedienne of Algeria. Col. Qaddafi of Libya also became an honorary liberal and, by implication, presumably also his house guests, from Idi Amin to Emperor Bokassa. The reasoning behind this labeling was that since these statesmen of the modern world were clearly not conservatives, they must be liberals, tertium non datur. Nor can they safely be called "radicals": Khomeini and Qaddafi would not welcome suggestions for a radical change in Islamic traditions.

All these men, and their many colleagues, belong to political cultures to which terms of 19th century Europe and America are not applicable. But this simple truth has not been accepted by most of our correspondents and editorialists. A poor Lebanese mountain villager is branded rigth-wing (or conservative, or reactionary) because he is Christian, whereas his equally poor neighbor from the next village is left-wing (liberal, progressive) because he is Moslem. For similar convincing reasons the separatist Polisario in North Africa has become left-wing, which makes the Moroccan Communists who den them their state "reactionary," by necessity.

Day in and day out we are told about "Marxist" governments in places such as Congo-Brazzaville, Ethiopia, South Yemen, Madagascar or Afghanistan. These countries may be a great many things, pro-Soviet and anti-American, they may import Cuban troops and East German policemen, but "Marxist" they certainly are not. Is Castro a Marxist? Once thought to be a "liberal," he is now generally termed a radical. But this is not of much help either; most people with a little sense of history will find Castro's style more like that of Mussolini than that of Lenin.

No important (and only a few unimportant) issues in world affairs can be explained in terms that belong to a bygone age and a different culture. Even in the United States, isolationism can be advocated (or criticized) from both a "liberal" and a "conservative" point of view, just as in the 1930s. Nor is there anything specifically "liberal" or "conservative" in supporting (or opposing) defense spending. So why are these misleading terms so frequently used?

Partly, no doubt, out of ignorance, one of the most underrated factors in politics. Partly out of the desire to save valuable newsprint or time on the air. It is so much easier to use one short adjective than to explain at length.

But it is unfortunately also true that Spinoza may have been too trusting a soul. Quite frequently the "mistake" is dilberate. Some labels are more fashionable and attractive than others. One example should suffice. Almost no day passes without some reference to "urban guerrillas" in part of the globe or another. There is guerrilla warfare and there is terrorism; for a variety of reasons, technical and others, guerrilla warfare does not, however, take place in cities. If so, why the systematic obfuscation? For a very good reason: The term "guerrilla" has a positive public relations image; terrorism does not. Few terrorists like to be called terrorists. Thus with the help of sympathetic or gullible or careless media they are transformed into "urban guerrillas."

All this is of more than semantic importance. Misleading language does not contribute to clarity of thought or to an effective foreign policy. One should be suspicious when next confronted with such labels as "conservatives" or "neo-conservatives" and "liberals," "left wing" and "right wing," in an Outer Mongolian context -- but also in discussions of our own foreigh policy. It may be a honest mistake or carelessness, but it could also be deliberate obfuscation.