Courtesy of Putin, debates about the origin and nature of evil regimes have perked up. Political scientists, both in Russia and elsewhere, are arguing about Putinism. Is it fascism? Nazism? National Bolshevism? (I’m strictly mentioning plausible versions, not the panegyrics peddled by Putin’s trolls.) Alas, when it comes to political terminology, confusion reigns. Words are used imprecisely, with their core meaning muted by emotional overtones. Connotation wipes out denotation. Subtext dominates text. Even founders of political movements often don’t understand their true nature. That’s because political convictions aren’t always, and never merely, rational. As often as not they come from...