Nobel laureate Gary Becker and legal collossus Richard Posner have now opened their blog, to much fanfare. Their first set of posts take up the issue of preemptive war.
They point out that defensive military actions might be necessary in anticipation of attack, before the attack has come to fruition, so as to avoid catastrophe. That is, of course, right. But it's merely the obvious starting point, one well-understood by every serious scholar writing in the area (despite Becker's odd claim that their opponents on the issue don't recognize this--has he read his opponents' scholarship?).
The issue is not whether one should act preemptively, but rather whether one can do so with disregard for the opinions of the rest of humanity. Becker/Posner seem to see the issue from the perspective of a state that they trust making the decision that its security is at grave risk and acting accordingly.
But the issue in international law is what the general rule should be, not what the rule should be for the United States alone.
A permissive regime with respect to unilateral preemptive self-defense, one that authorizes any state to decide for itself without subsequent appraisal whether it faces a risk of attack, would authorize not just the United States to act, but also our enemies.
Should Iran be authorized to say that it sees a risk of attack by the United States (or any other state), and then attack that state preemptively?
Becker/Posner should begin their blog by reviewing the golden rule.