A new crop of researchers hope that computational psychiatry will shift how we understand the mind, which could lead to novel ways to diagnose and treat psychiatric disorders — “To change something, build a new model that makes the existing model obsolete.” — Buckminster Fuller. One rainy Wednesday evening in November, I had dinner in Mayfair, central London, with a successful filmmaker, whom I’ll call Arthur. I thought I had him pinned after the first course of a rather…