Now I realize, of course, that many readers will acknowledge that we do in fact have these reactions, but would nevertheless write them off as mere reactions. “Our tendency to find something personally disgusting,” they will sniff, “doesn’t show that there is anything objectively wrong with it.” This is the sort of stupidity-masquerading-as-insight that absolutely pervades modern intellectual life, and it has the same source as so many other contemporary intellectual pathologies: the abandonment of the classical realism of the great Greek and Scholastic philosophers, and especially of Aristotle’s doctrine of the four causes.