[WARNING: This is L O N G, even for me. On reading it over with a cooler head I realized that I was using Putnum to represent the hundreds of idiotic arguments I've heard in this matter when in fact, Mr. Putnum can only lay claim to a few of them. In other words, I am mostly blowing off steam.]
For the most part I have the disposition of a sloth on sleeping pills: mellow to the point of torpor. But there is one issue that never fails to arouse my anger: naked emperors. And Cliff's excellent book reviews (I wish I could take his course) reminded me of a whole pack of emperors who have been strutting about for years now buck naked.
I refer to the set of eminent philosophers who deny that the brain is a natural object, subject to the same laws of physics that the rest of the universe obeys. The mind, they say, is beyond all hope of understanding, but whatever it is, it sure isn't a (YETCH) computer! This Hilary Putnam is near the head of the parade and I repeat: THE EMPEROR HAS NO CLOTHES!
I don't care if Hilary Putnam is the king of syllogigms, the reincarnation of Plato, and the grand poobah of all philosophy - his arguments, and the arguments of others like him, just don't hold water. We're talking a C- in logic 101! We're talking the most circular arguments and gaping holes since Descartes' "proof" of the existence of god! But enough name calling. Let me try to touch on one or two of the ways in which Putnum and his ilk go astray.
First, their motivation. Putnum is apparently only the latest of a long line of people who feel that man is at the center of the universe and is some how apart and above the laws of nature. His ancestors believed that man was GEOGRAPHICALLY in the center of the universe. In fact they proved it many times (and tended to skewer, hang, or burn people who felt otherwise). If you compare Putnum's proofs to the proofs that the earth is at the center of the universe, you will find many striking similarities, and in particular the same sense of desperation. Just as they were somehow aghast at the notion that the earth was a "mere" planet, so Putnum is aghast that we may be "mere" computers.
With glacial slowness and obstinacy, Putnum's forbears finally acknowledged that the earth was part of a greater cosmos. They then tried to deny that man was an animal. Snails were animals, dogs were animals, but man surely was a kind of semi-angel. More centuries passed and more absurd proofs were filed until at last it was clear that we are part of the great family of life. We are animals and we live on a planet.
And now for the third time they step up to the plate. The earth is but one of many planets and our bodies are animal bodies, they say, but we possess a magical object called a mind. This object has many special properties. It can't be measured or touched or even understood. It may be connected to the pineal gland somehow but in such a way that it can't be detected. And most importantly, it is the only object in the universe not governed by the laws of physics. For this reason, they say, we are forever apart and above the rest of the universe.
But "mind" is not an object. It is a word. A word invented by children who simply had no other way of describing the experience of consciousness. It is a word very much like the word "alive", a magical word. If you set a kitten next to a rock, it seems that the kitten has some quality that the rock has not. It's not just fur or movement or warmth or eyes. It is all of these things together and more, some kind of whole greater the the sum of its parts. We don't quite understand it, so we give it a name: "Life."
It is a magic word that serves us well whenever we need to divide kittens and rocks into two separate piles. But until a few decades ago, it gave biologists a lot of trouble, because they kept looking for a precise definition of the word, and they kept finding things that were neither kittens nor rocks. The definition grew longer and more complex with an attached list of exceptions and special cases.
At long last a deeper understanding began to dawn. Life was a kind of vast chemical reaction. Kittens and rocks were not so different after all. It's just that kittens are more complicated than rocks. Everything is made out of the same stuff, and the stuff moves and changes according to the same set of rules. And when a glob of stuff becomes sufficiently complex you can say that it's alive (if you WANT to). "Alive" is just a word.
"Mind" is a word like that. We had no way of understanding "Alive" until we learned something about chemistry. And we had no way of understanding "Mind" until we learned something about computers.
The problem with these wayward philosophers is that they don't understand what words are and how they work. So they invent their own words without realizing it, and tie those words into pretty knots, and then stand to take a bow.
One word they have particular trouble with is "computer." They assume that a computer is a machine in a metal box that follows instructions "mindlessly." And this is not an unreasonable definition of most of the computers in existence today, even including our own beloved Macs. But we have only begun to build computers. There is no end to the possible variation in design. Putnum has seen one amoeba and concludes that no animal can fly because animals are too small and gooey.
What's missing is a deeper understanding of what a computer really is: a symbol processor. And since you can use just about ANYTHING to represent a symbol, any system that channels the forces of nature in an organized fashion can be seen as a kind of computer. My point is that the critics of artificial intelligence and cognitive science tend to have an extremely narrow view of computers. Computers don't HAVE to be "programmed" in the ordinary sense of the word and they can be far more flexible than Putnum would have you believe.
One of the reasons this is so hard to accept is that most people don't have a good understanding of EMERGENT properties. Color is a good example. Where is the redness of an apple? Is an apple built out of red atoms? An atom does not have a color, but certain clumps of atoms do. So where does color come from? The answer is that it emerges from a simpler set of properties.
I believe that "intelligence" is an emergent property (I put the word in quotes to remind me that it's just that: a word). Actually, it may not be wise to call it a property, because it's not quantifiable in the way that color is. It's another magic word like "Alive," and like many magic words, I think it is a quality that emerges from the properties of simpler objects.
I believe this because I have designed and built simple computers with my own hands. The parts of a computer are essentially quite simple. A transistor is simply a switch or gate. And when you put several of them together you form a path, and the paths in turn form a simple maze with an entrance and an exit. Electron mice run these mazes in a predictable way. And that's all there is to it, really. If you can understand what a door is, and what a hallway is, then you can build a computer.
I suppose the trick is that the maze imposes a certain order on a tiny piece of the universe; it gives the forces of nature a certain brief shape. And that shape can be analogous to certain mathematical or logical or symbolic relationships. A circuit board is a kind of metaphor.
The astonishing thing is that when these ordinary sand and plastic mazes reach a certain level of complexity, they start to "behave" in ways that seem to TRANSCEND the behavior of ordinary piles of sand. All of this is well within the laws of physics, and yet the experience of being surprised by a pile of sand is so breathtaking that it seems like magic. I cannot begin to describe the vast depth and scope of that transcendent behavior, and the strangeness of it, but after fifteen years I can tell you that I have seen only the most infinitesimal fraction of what is possible, and I was convinced long ago that the sum of all possible human behavior is a mere drop in the ocean of all possible computer behavior.
I hope I'm not being too mystical here. The experience of watching complexity emerge from simplicity is available to anyone with the courage to see. And you need only experience it once to grasp the general principle of transcendent behavior, and to see that we DO live in a COSMOS, not a CHAOS. The laws of nature are not chains to be broken, but form instead the skeleton of all possibility. It is this unyielding, "mindless" skeleton that makes all movement possible, even the fluid grace of a ballerina. In the same way, the unyielding, "mindless" components of a computer can move in ways beyond our dreams!
The arrogance of these popes and Putnums! Turning up their noses at "mere" computers! As if we should be ashamed to live in a "mere" universe.
This has not been a formal argument. Putnam's particular line of attack is only one of many and if Cliff want's to play Devil's advocate and present Putnum's arguments in more detail, I would enjoy trying to refute them with somewhat less oratory then I have used here. But neither Putnum nor I will ever really prove anything one way or the other.
What will happen instead, I think, is that over the next century or so computers will become more and more "intelligent", some of them clever in ways that are quite alien to human cleverness, some so much alike us that they will seem "human." Those who follow Putnum will claim at first this is some kind of trick, and that deep down "we" are better or at least different than "they" are. But in the end, computer intelligence will become so utterly commonplace, and at the same time so varied and full of surprises, that all reasonable people will recognize the underlying similarities between "them" and "us."
I do not offer a proof, yet I feel as certain about this as some people felt about man's ability to fly in the air a century or more ago. To be sure, Orville and Wilbur had many Putnums to contend with, but they could be as sure about airplanes as they could about the ability of birds to fly, because they saw the underlying principles, the lift and thrust of it all. The evidence was all around them, and in that moment when all the pieces of the puzzle came together, and they saw that birds did not violate the laws of physics but exulted in them, the world was suddenly a simpler place and we had more in common with the birds than we thought. We now find ourselves on the threshold of another kind of flight and we must choose between the Putnums of this world and the Wrights. The evidence is all around us. We have only to look in the mirror.