On Philosophy

August 4, 2006

Phenomenal Information and Context

Filed under: Mind — Peter @ 12:16 am

I assume that most of you are familiar with the thought experiment about Mary the color scientist, but just in case you aren’t here is a condensed version of it: Consider a scientist, Mary, who for her entire life is prevented from seeing any colors except black and white (although she is not colorblind). Mary however studies color perception, and knows everything about it that objective science can discover (all the physical facts). Despite this we still think that Mary will come to have some new knowledge about what it feels like to see color when she is allowed to see color for the first time. From this it is argued that there must be something non-physical about consciousness that accounts for the source of the information that experience provides (since clearly it doesn’t come from the physical facts), and thus that materialism is wrong.

Perhaps though we are being misled by faulty intuitions about experience or knowledge. Let me develop another thought experiment that is analogous to the one above in order to explore this possibility. Consider then Conway’s game of life. The game of life is played on a field of squares, each of which can be either on or off. In each round of the game the “state” (a square being on or off) can change based on the state of squares in the previous round. Specifically we mark a square in a given round as on only if it was on in the previous round and two or three of its neighboring squares were on, or if it was off in the previous round and exactly three of its neighbors were on. Although the rules are simple the game is not. There are patterns of squares that are stable, patterns that oscillate, and patterns that move (of course the pattern isn’t “really” moving, it is producing a copy of itself at a nearby location, but it looks the same). These moving patterns, called gliders, can themselves demonstrate some interesting behaviors. Specifically when gliders are arranged in the right way they can perform logical operations (such as and, or, not, ect). These simple logical operations are the same as the ones that are found in computer chips, and thus gliders can be used to simulate a computer running a program or programs. Let me run that by you again: a simple rule and a board of two-state squares can support complex patterns, which in turn can perform logical operations, which in turn can be used to make a computer.

Now let us say that we have a life-computer that is running a video game. We give that life board and the rules to Martha. We can now ask the question: does Martha know everything about the video game, or will she learn something more by playing it on a normal computer? I can say with certainty that she will learn something more, at the very least because she doesn’t know how to turn the glider outputs generated by our life-computer into the visual presentation that the computer monitor creates. In this case, unlike that of Mary the color scientist, it should seem clear that there is nothing non-physical about the computer program. Where does the new information come from then? The context. Specifically in the context of a monitor to interpret the output, and a mouse and keyboard to generate the input, we learn something about the program that we could have never figured out in their absence.

Like Martha’s study of the life-computer, Mary’s study of color is missing the context; specifically how color fits into her consciousness (which is essential to understanding her personal experience of color). Some might object, arguing that if materialism is correct then it is possible for Mary to understand how her own consciousness is dependant on the physical, and thus how the physical sensations of color will affect it. Such self-prediction is impossible however * (no system can predict its own behavior, see the halting problem), and thus Mary really can’t know how color will feel as part of a conscious experience without actually consciously experiencing it, not because the experience is non-physical, but because that information depends on a context which Mary can’t have complete knowledge about.

* This doesn’t mean understanding consciousness in general is impossible, just that understanding all the details about the physical basis for your own consciousness is impossible. Since you can’t even know all the details about the physical construction of your own desk (since it contains billions of atoms) this shouldn’t come as that much of a surprise.

** This also happens to be my 100th post. That is a lot of posts.

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