Paul Krugman has recently been claiming that people on the left understand the views of those on the right much better than people on the right understand the views of those on the left. As Bryan Caplan argues in his response, this partly hinges on the fact that Krugman is comparing left wing academics to right wing polemicists. If instead you compare how well libertarian economists can reproduce Keynesian arguments with how well Keynesian economists can reproduce libertarian arguments, the conclusion might well reverse.
The clever thing about Bryan's response is that he proposes an objective test of the question, a sort of ideological Turing test.
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.
If provided with sufficient funding, redo the experiment using economists, using political philosophers, replacing libertarians (or liberals) with conservatives. Generate some actual empirical evidence of who understands whose arguments well enough to defend them, which is arguably important, even essential, evidence of understanding them well enough to be justified in rejecting them.