This paper presents a decision theoretic model of the American side of the Vietnam war. That is, we only consider the U.S. government declared objectives and assign them utilities from that point of view. We assume that the involvement of the U.S. in this war was the outcome of a deliberate decision and, moreover, that this decision was taken on the basis of a careful weighing of goals and means. Hence decision theory is applicable in this case -and probably it was applied. We make hypotheses on the utilities of the goals and on those of the negative side effects. We also assess the probabilities of the four main possible courses of action available to achieve those goals: total war, advising, negotiating, and staying out. The total efficiencies of these turn out to be -0.30, -0.20, + 0.51, and -0.11 respectively. This result explains why neutrality was not tried and why the advisory policy was eventually given up. But it does not explain why war, which has been not just inefficient but countereffective, was preferred over negotiating from the start or keeping neutral. Unless of course one assumes that the strategists either (a) paid no attention to any decision theoretic models or (b) used models that had fatal flaws. If the first alternative is discarded because of the prestige enjoyed by decision theory amongst American executives, we must conclude that the decision theoretic models employed by the U.S. high command had either of the following defects: (a) they ignored or underrated the negative side effects accompanying the implementation of every goal, or (b) they were not supplemented by mathematical models of the decisions likely to be made by the other side. In either case the decision to adopt the strategy with minimal expected utility was. at best, rational but extremely ill informed. It may have been one more victory of ideology over science.
1. INTRODUCTION AND STATEMENT OF THE PROBLEM
It is no secret that the Vietnam war has been disastrous to the U.S.A., not to mention Indochina, in every possible respect. Yet the decision to get entangled in the civil war was presumably a deliberate resolution taken by a body of intelligent people in the light of the best expert opinion available to them. Moreover it is likely that the goals set by that body were not only explicitly formulated but also ranked and even weighed. It is also probable that the various possible means for attaining those objectives were listed and even assigned likelihoods of success. In short, it is reasonable to assume that the U.S. government's decision to plunge into the war was a rational decision, i.e. one assigned maximal utility. What then went wrong?