Periodically, and almost from the day he became a serious presidential candidate, editorialists, pundits, academics, and reporters have described Barack Obama’s foreign policy as a return to “realism.” Essayist and self-described realist Robert Kaplan, to take just one example, argues that this is something like a natural recalibration, a return to geographic and historical inevitabilities.

The opposite of realism, in this straw-man structure, is “idealism,” or “Wilsonian idealism.” For realists, idealism is like a bad pair of eyeglasses, lenses that not only focus on impossibly utopian goals but also prevent a clear assessment of the balance of power.  In its full political-science costume, realism is also supposed to be a description of the way power actually works. It’s supposed to be capable of predicting outcomes.