IT OCCURRED to us by some advanced point last week that if the pounding didn't stop we were going to find ourselves in the unaccustomed position of defending Zbigniew Brzezinski. Well, here we are. On the opposite page today we reprint excerpts from an extraordinarily (though not for him) blunt and candid article written by Hodding Carter in Playboy. Mr. Carter, as those who had read the newspaper accounts of this article know, lets Mr. Brzezinski have it pretty good, characterizing both the national security assistant's policies and his tactics and sense of his own role was wrongheaded, cunning and destructive. But one very important aspect of Hodding Carter's assault that deserves more notice than it got is this: the former State Department spokesman is very clear and specific about the source of Mr. Brzezinski's freedom to maneuver and to express and even impose his views. It was the president, Jimmy Carter.

This point seems to us worth stressing since not all of Mr. Brzezinski's newly articulate critics are as fair-minded and direct about it as Hodding Carter is. We will leave for another day an assessment of the value -- the rightness and wrongness -- of Mr. Brzezinski's various interventions in foreign policy. He is a man of weirdly unabashed candor himself in many respects, as likely as not to observe cheerfully, when confronted with complaints about the American condition in the Persian Gulf Region since the overthrow of the shah, that he himself of course had favored a military coup -- too bad it didn't come off. Mr. Brzezinski, in other words, whatever his special competence at bureaucratic infighting may have been, did not exactly disguise his bent of mind or his intense concern to prevail over those in the State Department and elsewhere whom he considered adversaries, wobblies and dopes. If President Carter didn't know what Mr. Brzezinski was up to, that in itself would almost have been grounds for impeachment, since he would have been the only person in Washington over the age of nine who didn't.

But of course he did. Jimmy Carter was heard to say after Cyrus Vance had resigned and Edmund Muskie was nominated to replace him that the Brzezinski "issue" was not, so far as he was concerned, an issue at all, that he had told his new secretary of state that he, the president, knew , Mr. Brzezinski was an aggressive, combative sort of a fellow who got in everybody's hair and that that was the way the president wanted it and he was sure the thing could be arranged amicably and productively for all concerned. Whether or not the president has reined in or overruled Mr. Brzezinski on the Haig-documents matter is something to be discussed in the larger context of that dispute. We stress the president's sponsorship of his national security aide now as the memoir battes are getting under way and as it appears that Mr. Brzezinski might turn out the scapegoat of choice. Remember this: he did not draw his authority and his cheek from nowhere.