When you get a concussion, the few instants before it happened are obliterated from your mind, as if you had never been conscious at that time. Just think—if you were knocked on the head at this moment, there would be no permanent trace left in your brain of your having read these past few sentences. Who, then, has been experiencing them? Does an experience only become part of you once it has been committed to long-term memory? Who is it that has dreamt all those many dreams you don’t remember one bit of?
Just as “now” and “I” are closely related terms, so are “here” and “I.” Consider the fact that you are now experiencing death, in a curious way. Not being in Paris right now, you know what it is like to be dead in Paris. No lights, no sounds—nothing. The same goes for Timbuctu. In fact, you are dead everywhere—except for one small spot. Just think how close you are to being dead everywhere! And you are also dead in all other moments than right now. That one small piece of space-time you are alive in doesn’t just happen to be where your body is now—it is defined by your body and by the concept of “now.” Our languages all have words that incorporate a rich set of associations with “here” and “now” namely, “I” and “me” and so on.
Now to program a computer to use words like “I” and “me” and “my” in describing its own relation to the world is a common thing. Of course, behind those words there need not stand any sophisticated self-concept—but there may. In essence, any physical representational system, as defined earlier in the commentary on the “Prelude, Ant Fugue” (selection 11), is an embodiment of some point of view, however modest. This explicit connection between “having a point of view” and “being a representational system” now provides a step forward in thinking about BAT-itude, for if we can equate BATs with physical representational systems of sufficient richness in their repertoire of categories and sufficiently well-indexed memories of their worldlines, we will have objectified at least some of subjectivity.
It should be pointed out that what is strange about the idea of “being a bat” is not that bats sense the outside world in a bizarre way—it is that bats clearly have a highly reduced collection of conceptual and perceptual categories, compared to what we humans have. Sensory modalities are surprisingly interchangeable and equivalent, in some sense. For instance, it is possible to induce visual experiences in both blind and sighted people through the sensation of touch. A grid of over a thousand stimulators driven by a television camera is placed against a person’s back. The sensations are carried to the brain where their processing can induce the having of visual experiences. A sighted woman reports on her experience of prosthetic vision:
I sat blindfolded in the chair, the TSR cones cold against my back. At first I felt only formless waves of sensation. Collins said he was just waving his hand in front of me so that I could get used to the feeling. Suddenly I felt or saw, I wasn’t sure which, a black triangle in the lower left corner of a square. The sensation was hard to pinpoint. I felt vibrations on my back, but the triangle appeared in a square frame inside my head. (Nancy Hechinger, “Seeing Without Eyes,” Science 81, March 1981, p. 43.)
Similar transcending of modality in sensory input is well known. As has been pointed out in earlier selections, people who wear prism-shaped glasses that turn everything upside down can, after two or three weeks, get quite used to seeing the world this way. And, on a more abstract plane, people who learn a new language still experience the world of ideas in pretty much the same way.
So it is really not the mode of transduction of stimuli into percepts or the nature of the thought-supporting medium that makes the “bat Weltanschauung” different from ours. It is the severely limited set of categories, together with the stress on what is important in life and what is not. It is the fact that bats cannot form notions such as “the human Weltanschauung” and joke about them, because they are too busy, always being in raw-survival mode.
What Nagel’s question forces us to think about—and think very hard about—is how we can map our mind onto that of a bat. What kind of representational system is the mind of a bat? Can we empathize with a bat? In this view, Nagel’s question seems intimately connected to the way in which one representational system emulates another, as discussed in the Reflections on selection 22. Would we learn something by asking a Sigma-5, “What is it like to be a DEC?” No, that would be a silly question. The reason it would be silly is this. An unprogrammed computer is not a representational system. Even when one computer has a program allowing it to emulate another, this does not give it the representational power to deal with the concepts involved in such a question. For that it would need a very sophisticated AI program—one that, among other things, could use the verb “be” in all the ways we do (including Nagel’s extended sense). The question to ask would be, rather, “What is it like for you, as a self-understanding AI program, to emulate another such program?” But then this question starts to resemble very strongly the question “What is it like for one person to empathize strongly with another?”
As we pointed out earlier, people do not have the patience or accuracy to emulate a computer for any length of time. When trying to put themselves in the shoes of other BATs, people tend to empathize, not to emulate. They “subvert” their own internal symbol systems by voluntarily adopting a global set of biases that modify the cascades of symbolic activity in their brains. It is not quite the same as taking LSD, although that too creates radical changes in the way that neurons communicate with one another. LSD does so unpredictably. Its effects depend on how it is spread about inside the brain, and that has nothing to do with what symbolizes what. LSD affects thought in somewhat the same way that having a bullet shot through your brain would affect thought—neither intrusive substance pays any regard to the symbolic power of the stuff in the brain.
But a bias established through symbolic channels—“Hey, let me think about how it would feel to be a bat”—sets up a mental context. Translated into less mentalistic and more physical terms, the act of trying to project yourself into a bat’s point of view activates some symbols in your brain. These symbols, as long as they remain activated, will contribute to the triggering patterns of all the other symbols that are activated. And the brain is sufficiently sophisticated that it can treat certain activations as stable—that is, as contexts—and other symbols then are activated in a subordinate manner. So when we attempt to “think bat,” we subvert our brains by setting up neural contexts that channel our thoughts along different pathways than they usually follow. (Too bad we can’t just “think Einstein” when we want!)
All this richness, however, cannot get us all the way to batitude. Each person’s self-symbol—the “personal nucleus,” or “gemma” in Lem’s personetics—has become, over his or her life, so large and complicated and idiosyncratic that it can no longer, chameleonlike, just assume the identity of another person or being. Its individual history is just too wound up in that little “knot” of a self-symbol.