“Conventional words are like the rules of a game. Calling someone stupid, or fearing being seen as stupid, doesn’t require you to know exactly what stupidity is.” How Not to be Stupid begins by defining stupidity, then moves well beyond the word itself, as any Sibaldi book does. In wartime, for example, we use conventional words like “general,” “civilian,” “enemy” and “order” without discussion or question. “It almost always works this way with conventional words,” Sibaldi says.