God Soul Mind Brain

would like to have the concepts placed in a larger perspective, then I urge you to read the entire book. It is, after all, short. I told the story as succinctly as I could.

    My interest in human consciousness comes from two directions. I am a neuroscientist and also a novelist. The novelist in me believes it is possible to give the general public a complete account of human consciousness, as far as it can be understood at the moment, without unduly complicated terminology, medical lists of brain nuclei, or equations. It should be possible to get right to business in plain English.

Two modes of perception

    In fifth grade some friends of mine played a joke on me.

    Just as I sat down at my school desk, the drawer slid open an inch. The explanation was obviously gravity acting on a loose slider mechanism. I pushed it closed and turned to my assignment, but a moment later the drawer pulled open again. That was odd. It was clearly broken. I would need to ask the teacher to look at it. Then I noticed a quivering blur in the corner of my eye. Glancing down, I saw a pale, cadaverous human hand emerging from the corner of the drawer.

    A decidedly impolite word escaped my lips, and the entire class turned to stare at me. The teacher was shocked. I began to realize the truth only when I heard suppressed giggles behind me. Two of my ever-helpful friends, it turned out, were playing with a length of fishing line and a rubber hand left over from Halloween.

    The experience is indelibly impressed in my memory. In the span of ten seconds my mind went through several distinct phases. First I perceived the movement to be a result of physical, mechanical forces. Nothing threatening. Then I had the sudden, spine-tingling perception that the movement was the result of intentionality. Zombie intentionality (if that is not an oxymoron). Finally I realized the true source of the intentionality, which turned out to be much more malevolent than any zombie.

    I out myself as a nerd—but even at that time, in fifth grade, and despite the casual cruelty of classroom humor, I was mostly astounded by a sudden scientific realization. The brain evidently came equipped with two totally different, complementary modes for explaining events in the world. The first mode was to find the physical cause of an event. Gravity, vibration, loose bolts, whatever. The second mode was to attribute intention to the event. Here were two fundamentally different styles of explanation. What struck me was the suddenness of the change from one to the other, as if a switch in my brain had turned to a new setting, from “that thing is inanimate” to “that thing is moving by choice.” A different circuit seemed to have turned on. I think everybody has had a similar if not quite so dramatic experience—the sudden, spine-tingling realization that something you thought was inanimate is actually alive, sentient, and acting under its own volition.

    That realization about a special mode of perception turns out to be essentially correct. The brain does contain special-purpose machinery whose job is to attribute volition, intentions, agendas, goals, emotions, and other mentalistic events.

    The ability to construct models of other minds is probably present in many species of animal, and probably varies with social complexity. Primates of all kinds have enormously complex social structures and therefore well-developed circuits for understanding other brains. Marine mammals have complex social interactions. Cat and dog species also depend on social interaction, although arguably the social structure in a lion pride is less rich and less gigantically complex than the social structure in monkey or human society. Even rats, mice, and many species of birds have social structures that may require some limited degree of perception of each other’s minds. The perception of intentionality need not be limited to within-species interactions. An antelope must look at a lion and perceive at a glance whether the cat is hunting or just passing by.

    Humans are particular experts. Our circuitry for social perception is so well developed that we find it second nature to guess at the inner goals and emotions of others. The skill is so natural that some readers may wonder why I am bothering to point out the obvious. Of course we intuit each other’s mental experiences.

    The importance of these brain circuits comes into rather horrible focus in cases when the circuits fail. In at least