The tell is more important than the telling:
Voters don’t have a great deal of knowledge about the issues, or a great deal of interest in acquiring knowledge about the issues. But they are human beings, equipped with our species’ excellent ability to read the emotional states of other human beings. If they see a politician acting defensive about his “side” in an argument, they conclude that this critics are probably on to something. If they see a politicians acting outraged and hitting back fearlessly, they’re likely to conclude that he has nothing to apologize for.
Unfortunately, Matthew Yglesias is may be right. Which makes most of what concerns me really esoteric or, as they say, wonkish.