When Do You Disengage?

I was speaking yesterday about political and economic versions of the “No True Scotsman” fallacy.  Namely, that someone who brushes off any criticisms of their pet theory by saying “that’s not pure X” while trying to blame real-world examples of Y for the problems of the world can be considered True Believers, who are not primarily driven by logic, but by emotion…faith.  Now I’ve never met anyone who didn’t do this (I take human equality on faith, for instance, and think that everyone really...