dave@cogsci.indiana.edu (David Chalmers) (04/03/89)
In article <5754@watdcsu.waterloo.edu> ssingh@watdcsu.waterloo.edu (Sanjay Singh) writes: >Agreed, if anything, the existence of higher intelligences creates >entropy faster than anything else. Well, in a sense higher intelligence (and high-level structures in general) tend to work against the inexorable flow towards entropy, by magnifying low-level randomness into high-level patterns. Both of these carry information, but at the high level it is much more robust than at the low level. High-level structures allow information to be conserved and transmitted - witness human brains, books, computers - thus providing relief against the Second Law, at least in the short term. Of course, you can't get something for nothing. The Second Law is a corollary of the fact that it is impossible for new information to be created in a deterministic universe. So where does high-level information, such as that found in people and books come from? The answer is: from low-level randomness. Such randomness carries information, but only in a very tentative form. But occasionally this randomness gets magnified into information at the top-level (for instance, by genetic mutation or by creative acts in the mind). At the top level, natural selection can apply (whether to organisms or to ideas), ensuring that the information which is left around is not a random mess but is in fact selected for quality. But, unfortunately, the Second Law tells us that this can't go on forever. In the end the supply of low-level information will be eaten up and turned into a homogeneous mass, and the top level will have no information to feed upon. At this stage the top level will turn into an almost empty, deterministic system. (Shades of Symbolic AI!) Of course, steps will be taken to preserve as much information as possible at the top level. In fact, this is already happening. The printing press and more recently the computer have seen to that. >This may sound misplaced, but can anyone CONCISELY and PRECISELY >explain the strong and weak anthropic principles. What are the implications, >if any, for intelligent machines? Is this more related to the >idea of life, or intelligence? ie. Does the anthropic principle say >something exclusively about life, or exclusively about intelligence, or >both? The Weak Anthropic Principle: Human life exists. From this fact we can draw conclusions about the way the universe is, and about the laws of physics, in an a priori fashion without the need for direct observation. For instance: from the fact that we are here today we can conclude that the laws of physics must be such as to allow the evolution of complex systems. We can also conclude, for instance, that the laws of gravity are such that a planet will not always plunge directly into the sun. There are less trivial examples, but I can't think of any offhand. The Strong Anthropic Principle: The laws of physics *must* be such as to allow the development of intelligent life. In a sense, this is obvious. Along the lines of the Weak Anthropic principle: we are here, so the universe must be structured so that we could get here. But the SAP claims more. It says, almost, that a universe without intelligent life is absurd. If there existed such a universe, there would be no-one to know about it, and so in what sense could it exist? There has also been proposed: The Final Anthropic Principle: The universe must be such as to allow the existence of an *infinite* amount of intelligent life. Don't ask me about this one. I could never understand the justification for it. The most common application of Anthropic Principles is to argue against religious arguments, and similar lines of thought. "Wow, isn't it *amazing* that the universe allows the existence of intelligent life. For instance, if certain physical constants had been just 2% different, then the proton would be unstable and things could never get off the ground. There must be something out there just making these things go right." To which the answer is: "No. If these things had been different, we wouldn't be here to talk about them. As it happens, we are here to talk about them. Therefore we shouldn't be surprised that the universe is this way." [By analogy: Somebody might say "Isn't it amazing that Earth has just the right temperature and atmosphere to support human life?" Of course this is not amazing. If Earth had been different we would not be here to talk about it. But presumably life could still have evolved on other planets around the universe, maybe only a few, but all of them going "Wow, isn't it amazing that *this* planet..."] The Anthropic Principle may be tautological, but it is still interesting. Various people have tried to argue against it, but in its Weak form it is impregnable. The Strong form is interesting but open to question. The AP can be viewed as a part answer to that age-old question, and still the second (or third) most burning philosophical question that exists: Why, of all the possible universes, are we in this one? Don't the laws of physics seem a little arbitrary? The AP says: well, we couldn't have just any old set of laws of physics. The laws have to be such that intelligent life can exist (otherwise we wouldn't be here to talk about it). For all we know, that rules out most possible sets of laws. Some even go so far to claim that ours is the *only* possible consistent universe in which intelligent life can develop, but I think that this is implausible. Dave Chalmers Center for Research on Concepts and Cognition Indiana University