We have all these ethics committees and ethics officers in Washington, wise ones attached to the agencies or in Congress, whose job it is to tell us when we have sinned and how badly. Otherwise we wouldn't know. We have no clear, generally applicable moral code here, although we have of course plenty of gasbagging about morality. This is indulged in no less by the press than by the politicians, but it is equally implausible and self-inflating in both cases.

Our problem is that the multitude of transactions that make up our daily political lives in Washington have a certain amount of hustle and fraud and a whole lot of moral ambivalence built into them: When is a contribution a bribe? When is "hardball," our loving term for political rough stuff, really foul play? We have a devil of a time deciding whether something has come to light that actually deserves to lead the news and to humiliate and ruin its perpetrators. After a couple of weeks of joyous accusations, we commend these agonizing dilemmas to the judgment of the ethics officers and experts. The town then goes on to other things, and seems almost indifferent when the committee, in due course, issues its finding. "As ax murders go," it will tell us, "this was no big deal. But the administration could have taken more steps to prevent it." COMMITTEE SEES AX MURDER AS 'NO BIG DEAL,' we will put on page 2,092, HINTS WHITE HOUSE CARELESSNESS.

And that will almost always be the end of it. The next time it will seem to be happening (as it always does) for the first time. We have no body of law, tradition or precedent to which we all repair when these things occur. Depending on whether we are associated with the accused or the accusers, we are likely to say that everybody does it or that nobody has ever done anything so singularly horrible before. That unedifying place is roughly where Washington is on the subject of the Carter briefing book as I write.

True, we are not in the presence of an ax murder. That much seems to be assured. But for the rest we are in midcontention, going through the chaotic procedures we have adopted for deciding whether we have a live one here. The elements that go into this preliminary decision are worth reflecting on. What causes us to focus on one episode from among many? How is the weight, the importance of such a crime, lapse or impropriety judged? What motivates the players? And what keeps the scandal growing?

It is sometimes said that the real legacy of the late Sen. Joseph R. McCarthy was a kind of immunization for any bona fide Soviet agents in our midst: people are skittish about calling even a real one a real one--it is thought to be "McCarthyite." The Watergate trauma has left a comparable legacy: afraid of underplaying, of being caught again, we overplay. I'm not saying we overplay everything or even that this particular flap may not have ugly dimensions as yet unrevealed (you see how scared it's made us?), only that there is this anxiety in the journalistic air, this fear of not following a big one to its proper conclusion, of looking the fool.

No one I've talked to has figured out a very good way to make the relevant distinctions here: how much does the resulting big story owe to journalistic selectivity and agitation, and how much does it owe to the intrinsic size and importance of the story itself? We tend to play it big and then say, "See, we told you it was big." But it is also true that the events start marching along in such a way as to strongly suggest that apart from our hyperactivity there was in fact something there.

Why do we pick up on the ones we do? Here, I believe accident and circumstance and unlucky (for the culprit) breaks have much to do with it--what's competing for the city's attention, etc. The Washington press and the permanent establishment are regularly denounced for their presumed anti-Republican bias, but I think that the bias is essentially anti-incumbent, pull-the-lion's-tail stuff that all administrations have to deal with. Naturally, this will not be admitted by anybody. Nor will the relish and amusement with which the city observes these recurrent proceedings.

That brings us to the second driving motivation after Watergatish fear of missing the big one. Politics in this city is a blood sport and people find the chase terribly entertaining, really funny. Politicians and journalists both, and all those legislative aides and lobbyists and bureaucrats and folks outside the pit where it is happening, are frankly having a wonderful time. They pretend to shock, horror, being morally scandalized, outraged. In fact they are enjoying the hell out of it. This is especially true of those long-faced, ideologically morose ones, the spoilsports who say that there are much more important issues--good old issues--in the world and how about the threat to Medicare financing. Everything about their reproving tone tells me that the political scandal is the first story they dive for when the morning paper hits the porch.

As the thing gets going, a third engine can be heard warming up: within the administration, or whatever camp it is that is under siege, internal political tensions and even hatreds begin to impel people to see a great opportunity to save themselves and do in their rivals. This is happening now in the Reagan White House. The Baker-Gergen-Stockman crew, involved in the briefing-book affair, is seen by its dedicated critics on the right as vulnerable to a knockout punch.

I should be plain: if the FBI, now in the case, finds a crime, or if there does turn out to have been truly organized, systematic robbing and pillage of the Carter campaign, then something dire should happen to those responsible. But my confidence is shaken by the fact that we have let some of the biggest political scandals go almost without comment and have commented extravagantly on some of those that, once in court or committee or under investigation, yielded nowhere near sufficient evidence to sustain all the earlier charges. Bert Lance, Hamilton Jordan, Raymond Donovan, and those legislators on Capitol Hill said to have been molesting little boys.

We do this so often, I wish we did it better.