The lesson of the CBS show on the doctoring of enemy strength estimates in Vietnam is simple: don't doctor estimates. It's much harder to cope with the condition that led to the doctoring. The United States was losing the war, or it was not winning in the way President Johnson wanted. That condition lingers in respect to our general international position. We are not -- not yet, anyway -- winning in the way President Reagan seems to want.

Much more is entailed here than the bias that frustration can impart to intelligence estimating. What does a country do when it's not winning? Fight on? Widen the war? Cut its losses? It is not a congenial question for Americans, but circumstances have compelled us to address it.

The initial Carter answer -- before Afghanistan -- was to seek out as broad an accommodation as possible with Moscow. Jimmy Carter's premise was that, to be prosperous and secure, the United States did not have to win in a conventional sense but just to reach a balance. He was sure it could be done.

The initial Reagan answer -- before Europe seemingly started going neutral under the shock -- was to prepare for a broad confrontation with Moscow. Openly dubious of accommodation, President Reagan seemed committed to the idea of winners and losers in the game of nations. His evident expectation was that at a certain point the Kremlin would say uncle.

Carter had to harden a lot. Reagan has begun to soften a little, how much we can't yet know. But we do know that his turn, tentative as it is, distresses many of his longtime supporters. It makes me wonder if those of us who are not so much troubled as comforted by the spectacle of a president's loosening grip on ideology may have underestimated the difficulties of Reagan's going further down that road.

I say this under the influence of a catch-up reading of a book written a dozen years ago by Fred C. Ikle. Then a defense intellectual, now he is undersecretary of defense for policy. "Every War Must End" (Columbia) is a succinct, beautifully argued essay on the little-studied question of how wars end. Though Ikle writes of hot wars, his analysis can be extended to the Cold War.

In a government's inevitable internal argument, he says, each faction espouses "peace with honor." A long struggle so deepens disagreement over national objectives, however, that the phrase loses its common meaning. Those who wish to end or ease the war risk exposing themselves to charges of betrayal or even treason. "Fear of this taint... deters senior officers and government officials from taking steps to end a war, even if they know full well that further fighting will do more harm than good..."

"Throughout the ages, states have sought to protect themselves against [treason] by strong moral and legal sanctions. Defenses are much weaker, however, against internal threats to the survival of a nation that stem from obstinacy in fighting on for unattainable aims... A dangerous asymmetry exists here in the protection of a state against two types of harmful acts by its own citizens."

"Cutting one's losses," Ikle goes on, "appears to be a particularly difficult decision for a government to reach in seeking to end a prolonged and unsuccessful war. The 'hawkish' and the 'dovish' factions, in thinking of their country and their people, might actually not be far apart in their deeper beliefs about what must be saved. Yet, in the eyes of the 'hawkish' faction, the acceptance of a partial defeat would not only expose these values to threats from without but start an internal process of politcal demoralization that would undermine them from within. And the 'dovish' faction believes just as strongly that continued fighting would destroy these values either through some final cataclysm or through increasing strife at home."

Yes, I am running a good bit ahead of the story. Scaled down to reflect the difference between a finite shooting war and an ongoing Cold War, however, these considerations seem to me to illuminate brilliantly the terrain of our politics today.

Ronald Reagan can be sure of moral and political fortification, although not necessarily success in his foreign policy, if he takes a hard line. But whatever tendencies he may have to let up will stir an intense reaction from the domestic quarter where he has the deepest roots. He is caught up -- I hope -- in the hawk's dilemma and there is no painless way out of it.