"How is it that Freud is not taught in psychology departments, Marx is not taught in economics, and Hegel is hardly taught in philosophy? Instead these masters of Western thought are taught in fields far from their own. Nowadays Freud is found in literature departments, Marx in film studies, and Hegel in German. But have they migrated, or have they been expelled? Perhaps the home fields of Freud, Marx, and Hegel have turned arid. Perhaps those disciplines have come to prize a scientistic ethos that drives away unruly thinkers. Or maybe they simply progress by sloughing off the past."Should we teach the phlogiston theory of fire to our chemistry students? Go on extended riffs about Ptolemy's epicycles before lecturing on astronomy? Preface math classes with a look at the geometric mysticism of Pythagoras?
Of course not.
But Freud and Marx occupy the same intellectual space: they were wrong, and they have long since been discredited. Freud's psychoanalysis was nonsense, an intentionally unfalsifiable mess with none of the basic empirical support that legitimate psychology demands. He might be valuable to students as an illustration of how not to do psychology, but that's it. Meanwhile, Marx's brand of pop economics is an interesting historical relic, if only because it spawned a real-world governing philosophy that impoverished millions. But it has literally nothing in common with the current science of economics.
Perhaps in a perfect intellectual world, where students would have the time to devour everything of even the slightest cultural or historical relevance, it would be beneficial to study Freud and Marx. We do not live in that world. Professors of economics have a difficult enough job prodding their students to understand supply and demand. They shouldn't have to waste their time lecturing about a mediocre theoretician whose only virtue was -- and is -- popularity.