Bryan Caplan writes:

To me, the interesting thing about the realist theory of IR is that it’s the national version of economists’ standard rational, selfish actor model.  While this model works well in some situations, I’ve argued at length that for individual political behavior, it’s dead wrong.  Voters’ beliefs are far from rational, and their motives are far from selfish.

If the rational, selfish actor model doesn’t even work for individual selves, it’s hard to believe it would work for entire countries.  On the other hand, though, maybe there’s a difference between group and individual behavior.  In the next two parts of this series, then, I’ll separately consider the two key planks of the realist theory of IR: The motivational assumption that each country’s goal is to maximize its national interest, and the cognitive assumption that each country acts on unbiased beliefs about how to achieve its national interest.

I’m no expert on this matter, but it seems to me that this analysis confuses an incidental feature of realist thought for an essential one. It may be true that classic articulations of foreign policy realism have tended to assume a robust conception of rationality in interpreting the policies of international actors, but by my lights at least it’s the emphasis on the pursuit of self-interest that is realism’s truly defining feature. Understood in this way, realism clearly leaves room for the possibility of actions that are based on a mere semblance of rationality; and by the same token, there’s no reason why it should be taken to rule out a priori the possibility of international actors who mistake for self-interest something that isn’t that after all. The idea that foreign affairs can be managed effectively by effectively manipulating these sorts of illusions, hence by trading on tendencies toward irrationality or mistaken understandings of self-interest in dealings with other nations, seems to me to be one that the realist has every reason to find congenial, and helpful aid to exactly the sort of non-idealized approach to statecraft that realists are committed to promoting.