An interesting post that just showed up in Google Reader is this lengthy reaction by Jacob Levy to Walt and Mearsheimer’s piece on the Israel lobby; I think here’s the meat of Levy’s argument:

They proceed to address this puzzle [of favorable U.S. policy towards Israel] with a slippery—I do not say sloppy—ambiguity between explanatory and evaluative claims.

The mere existence of the Lobby suggests that unconditional support for Israel is not in the American national interest. If it was, one would not need an organized special interest to bring it about.

This is, I think, the worst paragraph of political science I’ve read in many years. The best, most-justified policies don’t automatically spring into being at the end of the policy-making process. An all-things-considered judgment that X is the best policy is essentially irrelevant to one’s ability to predict whether or not X will be adopted. Political and policy-making actors aren’t, indeed couldn’t possibly be, such purely disinterested promoters of the public good that they could promote it all the time without any organized support—even assuming that they all agreed with each other, and with M&W, about what the public good consisted of. They often need organizational and material support from interest groups even to do [what they take to be] the right thing. ... From the fact that a policy needed a lobby to support it, one can infer nothing about the policy’s justifiability.

Not to mention that the authors missed a good opportunity to use the subjunctive voice. What writer on earth would pass that up?