More and more I see rationalist-fetish communities like LessWrong and the impractical theory-driven trend of modern ethical philosophy as symptoms of the same problem. Unfortunately, one of the seeds of that problem is an error by David Hume, my second-favourite philosopher. The main reason I like Hume is that, unlike my favourite philosopher Kierkegaard, Hume was pretty much right about everything: political philosophy, epistemology, reason and passion, metaphysics. He had a tremendous ability to think hard about a subject and, rather than multiplying the problem, either solve it or dissolve it into an error of semantics or sloppy formulation. But where Hume slipped up was in his view of human psychology.
Despite Hume’s method taking as its foundational principle the discovery and investigation of unspoken assumptions, Hume’s assumptions about the way the brain works went unquestioned. He presupposed a Newtonian atomic theory of mind: larger thoughts composed of smaller ones, which in turn are made up of smaller sentiments and impressions. Hume believed that all these mental objects were governed by laws in the same way that physical bodies are, and he devoted no small amount of time to uncovering those laws.
Hume is long dead – but today we have fools carrying his error so far that they describe the brain as like a computer (albeit a badly-designed one) and talk about uncovering the ‘algorithms’ that human thought uses. Next time I’ll go into a little more detail on why this is such a bad idea.