Psychology is blossoming today, but for much of its history it was dull, dull, dull. Perception was basically psychophysics, the study of the relationship between the physical magnitude of stimulus and of its perceived magnitude — that is, as you make a light brighter and brighter, does its subjective brightness increase at the same rate or not? It also studied illusions, like the ones on the back of the cereal box, but without much in the way of theory. Learning was the study of the rate at which rats press levers when they are rewarded with food pellets. Social psychology was a bunch of laboratory demonstrations showing that people could behave foolishly and be mindless conformists, but also without a trace of theory explaining why. It’s only recently, in dialogue with other disciplines, that psychology has begun to answer the “why” questions. Cognitive science, for example, which connects psychology to linguistics, theoretical computer science, and philosophy of mind, has helped explain intelligence in terms of information, computation, and feedback. Evolutionary thinking is necessary to ask the “why” questions: “Why does the mind work the way it does instead of some other way in which it could have worked?” This crosstalk has made psychology more intellectually satisfying. It’s no longer just one damn phenomenon after another.