The proposition is this: everything in American political life happens approximately three years too late--or three years after it should have, which is often the same thing. We live in a world of trains that have, as the saying goes, "already pulled out of the station." That's bad enough. When we are really unlucky, we manage to catch one and sit there beaming with relief and self-satisfaction while we are hauled off to the wrong place. The onetime right and reasonable action or position will be put into effect only three years after it has (a)lost its timeliness and therefore any chance of doing what it was meant to, or (b)been demonstrated to be, in current circumstances, no longer either reasonable or right.

My precise three-year figure is open to negotiation, but the terrible abiding principle of policy lag is not. I insist on it and call as my first witness my mentor, Richard Nixon, ebulliently exclaiming in 1971, "I am now a Keynesian!" This, alas, has been the pattern, and while Nixon may have been the one, he was far from being the only one. Washington, in fact, has a way of finally embracing controversial economic theories it has resisted only at that precise moment when droves of economists may be seen to be fleeing them in confusion. The belated warmhearted adoption of monetarism in this city is but the latest example.

The broad general positions of the political parties on economic questions, of course, reveal the same thing. It is grand that the Democrats and other assorted liberals have now discovered the mortal danger to the society of large public deficits and have become so unrelenting on the subject, as some of us have done. But how much grander it would have been, one can't help thinking, if we had all enjoyed this revelation at the time we were helping to create such whopping deficits ourselves. Ronald Reagan, doing as much as anyone around to corroborate the three-year-lag hypothesis, yields up his lifelong view that huge public deficits are simply not to be tolerated, just when it is beginning to look as if he may have been on to something.

I bring this up because the disturbing fact of it seems to be leering out at me from behind so many of the stories in the morning paper. Now that it is much less important as a gesture against the ineffable Muammar Qaddafi, we are considering--at last--a boycott of Libyan oil. Now that Central American and the Caribbean countries are well along the way to chaos and disaster--political, social, military and economic--we have an idea (Reagan's aid-plan idea) that might have prevented what it is now attempting to respond to, had the idea been thought of a few years back.

You can overdo the remorseful "if onlys," of course, especially in relation to American conduct in and toward other countries. I know we often have a half- arrogant, half-childish view that a big aid program and a lot of smiles, both unstintingly dispensed by us, could have transformed no-goodniks into statesmen abroad and drastically altered other people's history and habits. But even correcting for that, it does seem to me that almost everything about our melancholy latter-day involvement in the Central American and Caribbean conflicts smacks of this out-of-date, never-quite- caught-up way of doing things. And while I don't think we have or ever had it in our power to control the destinies of these people, I do think that on all sides of the general argument in this country we are showing our invincible capacity for refusing to see any point until it is either too late or the point has become the wrong one.

I think this when I hear critics on the left complaining that "once again" we are coming in on the "wrong side" in these leftist-versus-military (or reactionary) conflicts. The assumption here is that there is a "right side," not just two that aren't very good. We come late to the perception that there is a strong social claim to be made in these countries against some of the very unlovely types with whom we have been allied. We will come even later, as in Indochina, to the perception that many who pretend to represent a social-reforming, populist alternative are no lovelier than our own cops and generals --sometimes worse--and are not entitled, even by indirection and implication, to the term "right side."

Will we find out in El Salvador not only this, but also that what should have been done by way of reform and strengthening security several years ago is too little/too late now? That it even may make things worse? I write as one who is for giving it a chance, but not optimistic about the result.

The question arises: why are we so regularly and so pathetically out of step, out of time in our practices? In some realms, mere technical or institutional answers will do. Exhibit A would be our whole agglomeration of procedures for creating a military establishment. By the time you get a program or a weapons system going, it is likely to be well into obsolescence. But I think in other realms of our public life it is some combination of stubbornness and wrongheadedness about changing our minds that gets us into trouble.

We are great on hideous, weepy televised confessions in this country. They have almost become an art form--the dutiful, if traumatized, family standing by the wretched political father who is cheerfully confessing to some ghastly lapse of dignity and taste. But we are not so good at saying or even acknowledging to ourselves that we were wrong, that we are wrong. It is thought to be political suicide, stupid public relations and, besides, evidence of a personal failure.

So we persist. How long? Exactly as long (here I come back to my hunch of three years on average) as it takes for the idea we are resisting to become either obsolete or newly acceptable to our side in an argument, or both. And then we make the safe and comfortable switch, becoming so pleased with our liberation from some older tyranny, that is, our dogma on deficits or popular Marxist revolutions or whatever, that we don't notice we are doing it again.>

Don't get me wrong: late-in-the-game conversions have a great and honorable history in our culture. But Saint Paul, the paragon, started a religion with his, while all we seem to be able to start is a run on the banks or a palace revolution. Ronald Reagan and his antagonists at home could do worse than to think about this.