UNTIL LAST Wednesday I assumed that it is one of the functions of an ambassador to have unofficial, and even unauthorized, meetings with those whom his government is unable to meet for reasons of protocol; that it is one of his functions to reach and feel where his government cannot officially be seen to go; that it is one of his functions to be a supplier of information to his government about everything that is going on in the country in which he is stationed; and that if he is caught in the act, his government will assist him to dissemble, and not publicly put him to the thumbscrew.

It is important to be clear that I am writing only about the function of diplomacy. I am not writing about the future of Israel, or the rights of the Palestinians, or the blacks and the Jews in this country. I may have definite opinions about all of those, but they are not here my subject. I am concerned with the position and the role of an ambassador.

The classic work on diplomatic practice was written by Sir Ernest Satow, a scholar-diplomat of the last century, after his retirement in 1905, and its fifth and fully revised edition has just appeared. It now has to have elaborate chapters on subjects like "Kidnaping of Diplomats." This up-to-date edition begins by quoting the definition of "diplomacy" in the Oxford English Dictionary. Diplomacy is (i) "the management of international relations by negotiation." But then it is (ii) "the method by which these relations are adjusted by ambassadors and envoys." We are not surprised to read that; it is what most of us mean by the word.

It is true that Satow goes on to say that, "strictly speaking, the head of the foreign department is also a diplomatist," but he goes on to believe this, as one would expect, by writing almost entirely about the "diplomatic agents": ambassadors, legates and nuncios, envoys, internuncios and charges d'affaires. Whatever may be true "strictly speaking," these are who we sensibly understand to be diplomats.

Satow is not at all clear about the people to whom an ambassador has the right to talk and even negotiate with on behalf of his government, except to point out that he has no right to go behind the back of the minister of foreign affairs in the country to which he is appointed in order to negotiate with the sovereign of that country directly. Of course there is no way in which more than the barest rules could be laid down to define how an ambassador should go about his business in every situation. The ambassador must be broadly free to use his own "tact and intelligence," as Satow puts it in his first sentence, otherwise his usefulness to his government and country will be very circumscribed.

Only a few months ago the foreign service of the United States was being criticized because it had made no fruitful contacts with the Ayotollah Khomeini while he was an exile in Paris, and because it had given no warning of how widespread and intense was the support on which he could initially rely in his own country. It is a very touchy matter to decide how far an ambassador should be in touch with the opposition to a government to which he is accredited, and when a situation is most delicate it is even touchier to draw the line between just being in touch and negotiating. But that is why we have ambassadors and it will be a poor day for the United States if the only contacts which it can make are confined to the stiff-necked diplomacy of which the government at home is capable.

A State Department or a Foreign Office are political. They are subject to the immediate political pressures that bear on their president or prime minister. The secretary of state cannot be concerned only with Israel or the Palestinians; he has to be aware, like his president, of the constituencies of Jews and blacks at home. The ambassador is at one remove from these pressures. He serves his sovereign -- a king in the past; the people now -- and not just a ministry. He is in duty bound to form his own estimate of the national interest in the country to which he is posted, and if he is asked to accommodate his actions too strictly to the concerns of the government at home his usefulness even to it will be diminished.

By accepting the resignation of Andrew Young -- at what appears to be the insistence of the State Department, and against the advice and inclination of some of his White House staff -- the president has politicized the ambassador's role. The danger in this is to him as much as to anyone else. What the president has said is that everything that his ambassadors say and do, unless he dismisses them, is his own word or act for which he can be held accountable by the world. He can no longer say, of an exploration that his ambassador is making, "But that was not me."

Refusing to lie on behalf of his ambassador, he is making it difficult to lie on behalf of himself. The false ideal of "truth in government" has never looked more threadbare. This administration is in the middle of making a major shift in policy when it is not in very good shape at home or abroad. Lambs are being thrown on the altar to propitiate the gods with a wantonness that would have astounded the most primitive societies. Andrew Young was hardly out of line with that policy at all, and only in the most inflexible technical sense did he defy protocol. There would have been no difficulty with what he said -- no protest from Israel -- if the policy of the home government had been clear.

In these circumstances, at the first inkling of what was afoot, the president should have sat on the State Department, and told it to lie: to concoct a lie with Andrew Young, and stick to it until the fuss blew over.

It was Sir Henry Wotton, himself an ambassador, who made the remark: "An ambassador is an honest man who is sent to lie abroad for the good of his country." He had scribbled it as a joke in an album at Augsburg, and it was discovered by one of his enemies, who reported it to James I. That prissy king was profoundly shocked. He refused ever to employ Sir Henry again, whereas his predecessor, Elizabeth I, would have elevated him. Perhaps Sir Henry should not have made that joke -- it puts the matter too baldly -- but it does emphasize the awkward moral categories of public life.

The diplomatic or political lie is not the same as the private lie. One must be able to lie for one's allies -- how else sometimes are they to be protected? -- but also no less for one's enemies -- their positions as well must not be too lightly exposed. Neither ally nor enemy is now going to feel very certain that its private dealings with the American government will not be bruited abroad in the name of a private morality.

A government that is in as tricky a situation as American now is in the Middle East must be able to put some distance between it and its deeds until these have ripened. This is all the more important because of two factors which have made that distance hard to maintain.

The speed of modern communications has made it difficult to separate the actions of an ambassador from the government at home. It is therefore essential that the fiction of that distance should be maintained. The role of the ambassador -- which seems to have withered so much since the palmy days of the classical diplomacy of the past -- needs to be exaggerated. A government needs to be able to step back and let him appear to be somthing of a free agent. Again and again, Andrew Young did this to the benefit of his government and his country, which could (as they did) disown him. Since last Wednesday we must believe that ambassadors are in fact their governments.

What is more, the role of the ambassador to the United Nations is wholly of its own kind, with few conventions. He is really an ambassador to ambassadors, not to a sovereign or a government where the protocol is clear. Since it is one of the functions of ambassadors in foreign countries to talk to other ambassadors -- and not directly to their governments -- the collection of ambassadors in New York must obviously play a very curious and indefinable game. I would have thought that this is one of the advantages of the United Nations -- not what goes on in its public meetings, but the constant interplay of ambassadors who are day by day in touch with each other in a special environment.

In these circumstances, it would seem desirable that a government should pay special attention to keeping its distance from its U.N. ambassador. And as for the lying, let us not forget that it was an American government that lied to its U.N. ambassador, Adlai Stevenson, at the time of the Bay of Pigs fiasco, and made him lie. But what matters is that since last Wednesday we have to assume that American ambassadors are their governments, and not merely the representatives of them, and so American diplomacy will be bound by yet one more fetter to which "truth in government" and "sunshine laws" have already condemned it.

America is today significantly weaker than four days ago. I agree that Satow would not approve of all my emphasis, but then his is a very diplomatic guide to diplomacy.