Rationalism in politics III: Last ramble

Carl has a good commentary and compendium on a topic shared by one of my rambles below. (Unwisely perhaps, he actually quoted from it.)

A money quote from his commentary is that, according to rationalism in politics, "one is rational to the degree that one efficiently fulfills all of one’s irrational desires." (I might have written "arational desires," since the desires do not necessarily demand what is contrary to reason, though they do so often enough.) And another, "that economic thinking is injurious of conventional morality should go without saying." The nominally Christian right wing should take note, especially those who find nothing unseemly in the juxtaposition of Ron Paul with St. Paul. A third: "Judge Posner’s much vaunted application of economics to law is less radical than is supposed. He merely does openly what others do in private." Another good post of his, on a related topic, lies here.

I have one thing to say on one of his selections. I find the quote from Yakuyuki provides a pyrrhic apology for economics (subject to the translation and the selection of course). According to Yakuyuki, when economists speak about rationality, "they aren’t saying something impossible, like for example that person A knows everything, has a model of society, understands economic conditions and so forth, and acts on all that." It's probably true certain economists think this way about economics from time to time. But speaking precisely economists do predicate all their analysis on the behavior of an impossible human being, and what is more, we have to—indeed anything else is less than science. It is true homo economicus cannot exist, but impossibility is not inconceivability. Economic man can be conceived of and compared to actual man even if he does not exist. Indeed that is what we must do if we want to understand incentives. Only by reference to the benchmark of how a perfectly rational man would act can we describe or predict, to any degree, how a partially rational man might act. Prediction depends on the understanding of nature; a thing's nature is given by the class of the thing. "True knowledge is knowledge of the forms."

To say we do otherwise is to abandon the analytic method unique to economists. It would turn economics into something else. Humanists (by which I mean, students of the liberal arts) are often troubled by our method, but we use this style of thinking whenever we abstract—as, again, we must, if what we are doing can be properly described as thinking.