The fact that people are so willing to support war is a puzzle that requires an explanation. After all, war is a negative-sum activity, so war between rational parties doesn’t make sense – there’s always a potential settlement that would leave both sides better off*. And empirically, it’s usually the case that both sides end up worse off relative to both the status quo ante or to a possible peace settlement they could have secured at a point well before the end of the war. Even the observation that rulers start wars and ordinary people bear the costs doesn’t help much – leaders who start losing wars usually lose their jobs and sometimes more, while winning a war is by no means a guarantee of continued political success (ask Bush I) All of this suggests that looking for rational explanations of war, as in the ‘realist’ tradition (scare quotes indicate that this self-ascribed title has little to with a reality-based focus on the real world) is not a good starting point.
So it makes sense to look at irrational sources of support for war. In this pice in Foreign Policy Daniel Kahneman (winner of the economics Nobel a couple of years back) and Jonathan Renshon start looking at some well-known cognitive biases and find that they tend systematically to favor hawkish rather than dovish behavior. The most important, in the context of today’s news is “double or nothing” bias, which is well-known in studies of choice under uncertainty as risk-seeking in the domain of losses (something first observed by Kahneman and Amos Tversky in their classic paper on prospect theory).
The basic point is that people tend to cast problems like whether to continue a war that is going badly in win-lose terms and to be prepared to accept a high probability of greater losses in return for a small probability of winning or breaking even. So we get the Big Push, the Surge, the last throw of the dice and so on.
There are other biases that are based more in the way we manage things as a society than in individual psychology. The most important is the failure to treat decisions about war in terms of opportunity cost, by contrast with the way in which the budgeting process of governments (admittedly imperfectly) brings home the cost of other government activities. More on this soon, I hope.
* This is not necessarily the case if your opponent is irrationally bent on your destruction, but one of the problems noted by Kahneman and Renshon is that people are overly willing to impute such motives to others, while perceiving themselves as peaceful and reasonable.