Leaving aside the rather ancient provenance of this idea, in the current context it means that Neo's mind is being fed false sensory impressions by the Matrix (otherwise known as Descartes' Evil Genius). Neo's mind is real; the outside world (including the spoon) is just a computer simulation. Notice the clean distinction between the two. The Matrix plays on this so-called Cartesian split of reality into individual mind on the one hand, and everything else, on the other.

So much for philosophy 101. The point is that this Cartesian split is as endemic in SF as it is anywhere else. It commonly appears in the core tenet of extropian faith: that the brain is a computer and the mind is a program. In the future we'll be able to download out minds into a less perishable medium than our current biological bodies. At least in The Matrix Neo still has a physical body; after downloading, he would exist only as a program running in the Matrix itself.

I don't actually believe that this is impossible; but the process has radically different implications than the extropians believe. And this is because the brain as hardware/mind as software metaphor is deeply flawed.

There's a great book that explains this stuff in detail: Being There, by Andy Clark. Rather than try to summarize the whole argument, though, a couple of examples might suffice:

• In classical studies of AI, they used to say that catching a fly ball in baseball was an example of the marvelous processing power of the brain. In order to calculate the trajectory of the ball, after all, a computer has to do some pretty fancy calculus; and yet we seem to do this math automatically, unconsciously, and on-the-fly. This implies some pretty fancy programming in the operating system.

  Actually, what we do isn't fancy at all. If you want to catch a fly ball, you run towards it while visually keeping the ball at the same angle with respect to the horizon. Do this, and you will catch the ball. No calculus needed, no mental program existing anywhere to calculate trajectories.

• The typical AI vision of mind is that it keeps an internal representation of the outside world in "software" form, updating it dozens of times a second. As it turns out, this is not true. If you operated off an internal representation of the outside world, you should be able to step outside your door, look around for a while, then close your eyes and walk to the end of the block. Or, you should be able to lay out all the pieces of a jigsaw puzzle, look a them for a while, then assemble the entire puzzle in your mind based on the representation of it you have there. The process of physically putting the puzzle together should take about five minutes. In fact the physical act of picking up, turning over and comparing puzzle pieces is part of the program; there may be an internal representation, but it's pretty peripheral to the real activity of solving the puzzle.

If the mind were a piece of software that created representations of the outside world, then Neo could be fed false information about that world--as 'inputs' to his 'program'. The spoon could be an illusion, a phantasm separate from the reality of the mind. But as Andy Clark points out, current research in cognitive science shows that we 'think' using any number of external props: the angle of the ball, the pieces of the puzzle are not simply inputs to an internal representation; they are connected via tight feedback loops to internal processes that simply don't operate without them. Clark uses the term "partial programs" to describe the internal side of these loops.

Partial programs are fascinating. If you think about a program as a recipe, then a partial program is a summarized recipe. Where a complete program for soup might include the instructions "add salt, taste, add more if needed; add chives, taste, add more if...", a partial program would simply have the line "season to taste". The human program for catching a pop fly is a partial program because it relies on the physics of the outside world to solve the calculus problem for it. As it turns out, most if not all human mental processes are partial programs when they are programs at all.

Insofar as the brain is a computer, it executes partial programs: crucial steps in cognitive processes take place outside of the brain, in the world. For instance, an elderly Alzheimer's patient might be assessed as incapable of taking care of herself; and yet when at home she might function perfectly well, if she has positioned the things she needs to prompt her to act in places where she can easily see them. Sitting on the couch, she literally has her memory arrayed about her, in the form of the clock on the mantlepiece, photos of loved ones, TV tuned today's weather, etc. The spices in the kitchen are where they have always been, and so on. And this is not an exception to a rule about how we think: it is the very rule itself.

If you think of the outside world as being a part of the internal process itself, and not just as something that is passively represented in the mind, then there is a spoon. The things of the world are not simply "thought of", they are part of thought itself in a very concrete and scientific sense. Watching the spoon, Neo is engaged in an action loop that includes his internal partial programs and something outside that completes the program. It may be a real spoon or only be a software construct; but either way it is a participating component of his mind. In other words, no more or less real than he is.

These findings have clear implications for the ideas of brain-taping, downloading personalities etc. Also in The Matrix, Neo learns Kung Fu by downloading the program for it into his mind. This would work if the brain as hardware/mind as software metaphor was accurate. But just as there's no 'program' for catching pop-flies, there's almost certainly no program for doing kung fu. The knowledge of how to do it lies in the nerves of the spinal column and extremities, as well as in the actual physical tone of the muscles and cartilage whose physical feedback completes the action loops of the partial programs in the spine... You could say that the partial programs residing in the spine and elsewhere are 'tuned' to the specific skeletal/muscular system with its particular masses and reslience. Mass and resilence complete partial programs, etc. etc. Hopefully you get the idea.

To download a mind into a computer, you need to download a complete physical representation of the physical body as well, and provide a complete Matrix-like representation of the physical world for them to interact with. Otherwise the partial programs don't run: it's like loading a computer program into your toaster. The instructions may go in, but the hardware needed to complete the action loops just isn't there.

So the disembodied mind in a box simply won't work. You need a body--and not just any body, but the one you've matured with, because its specific tuning is part of the action loops of your mind. And you need a world--and not just any old fantasy world, but one where gravity works the way it does at home, where your body breathes etc. It won't make sense for your now-disembodied mind to control reality simply using "thought" either, because "thought" is not an entirely internal thing.

A limited version of the idea might work, in which a person's entire body, and not just the brain, is scanned in; and where a new body is provided that gives the same feedback as the old and exists in the real world, or where the real world is fully duplicated as in The Matrix. You might preserve the identity and mind of a person this way. But it would represent a hell of a lot of work just to get you what you had to begin with. I could see it maybe to provide a sort of immortality, although clearly if the mind is not simply software, then what you would have in this case would be a copy of the person, because the 'person' does include the physical body and not just its data.

And ultimately, what's the point? As Andy Clark points out, in the end "the best representation of reality is reality itself."

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