Penfield’s classic brain experiments of the 1930s inspired a certain famous riddle, long since dubbed “brains in vats” by philosophy students. It goes like this: You think you’re sitting there reading this post. Actually, you could be a disembodied brain in a laboratory somewhere, soaking in a vat of nutrients. Electrodes are attached to the brain. And a mad scientist feeds it with a stream of electrical impulses that exactly...
