I recently finished Arnold Kling’s excellent Three Languages of Politics, which attempts to build a model to describe why different political viewpoints are so often not disagreeing as much as they are talking about different things entirely.

At one point Kling references this thought experiment proposed by economist Bryan Caplan — a Turing test for probing a person’s true ideology:

We don’t have to idly speculate about how well adherents of various ideologies understand each other. We can measure the performance of anyone inclined to boast about his superior insight.

How? Here’s just one approach. Put me and five random liberal social science Ph.D.s in a chat room. Let liberal readers ask questions for an hour, then vote on who isn’t really a liberal. Then put Krugman and five random libertarian social science Ph.D.s in a chat room. Let libertarian readers ask questions for an hour, then vote on who isn’t really a libertarian. Simple as that.