How do you make decisions when the outcome is uncertain? A good general rule is to hope for the best, but plan for the worst.
An example from the H-DIPLO mailing list (for historians of foreign policy):
From: Eric Bergerud
List Editor: "H-DIPLO [Rausch]"
Editor's Subject: Nixon, Kissinger, and Vietnam [Bergerud]
Author's Subject: Nixon, Kissinger, and Vietnam [Bergerud]
Date Written: Mon, 20 Oct 2003 11:34:28 -0700
I don't think I clearly addressed the issue of whether or not Nixon and/or Kissinger believed that the 1973 agreement would lead to the establishment of an independent non-communist [South] Vietnam (in which case the war would have been a "victory" every bit as much as Korea had been) or whether they believed that Paris would lead to a "decent interval" - a kind of sophisticated sell-out.
I am not sure that I can read Nixon's tea leaves on this issue. However, I think Kissinger's intentions are a little more understandable. Kissinger admired the great diplomats of the 19th Century: Metternich, Bismarck, etc. Bismarck in particular never thought that events could be predicted with precision. When a policy was pursued a range of outcomes could be expected. The trick was to develop policy where the minimum outcome (today we might call it a worst case scenario) was acceptable. If a triumph ensued great. If it was something in between, don't die of surprise.
It was no secret that many "Henry watchers" inside and outside the administration thought that Kissinger considered Thieu expendable. (Thieu thought this.) He did not desire the fall of SVN, but believed that LBJ and others had grossly overestimated the harm that a Hanoi victory would have on America's position. Kissinger was, however, extremely concerned about the overall course of the Cold War and wanted American concentration firmly pointed in the correct direction - dealing with Moscow. I rather think Kissinger enjoyed juggling the fears and desires of Moscow, Beijing and other lesser players. The biggest obstacle to playing the game, as made clear in his memoirs, was the Vietnam War.
Therefore Paris was a good deal from Kissinger's point of view. The minimum outcome was an American withdrawal from Vietnam and a face-saving interval of peace: an acceptable position from which to get down to truly important business even if the GVN failed in the end. The maximum outcome, which I suppose sounded feasible, was that Thieu would stick it out and the US could, at some future date, claim victory.
The important point is that wherever events fell on the minimum-maximum continuum, America was out of the war and had its hands free to play the great game on even terms. In sum, I think Kissinger would have considered Paris good work regardless of what took place ultimately in Vietnam.
How not to do it: E. H. Carr quotes Alfred Marshall.
Much that was said and written about international politics between 1919 and 1939 merited the stricture applied in another context by the economist Marshall, who compares "the nervous irresponsibility which conceives hasty utopian schemes" to the "bold facility of the weak player who will speedily solve the most difficult chess problem by taking on himself to move the black men as well as the white".