Xref: utzoo comp.ai:5290 talk.philosophy.misc:3372 sci.philosophy.tech:1820 Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!samsung!rex!ames!ncar!noao!stsci!bsimon From: bsimon@stsci.EDU (Bernie Simon) Newsgroups: comp.ai,talk.philosophy.misc,sci.philosophy.tech Subject: Re: Can Machines Think? Summary: from the fact that a physical system obeys causal laws it cannot be deduced that a computer can do what the physical system can do Message-ID: <1037@ra.stsci.edu> Date: 27 Dec 89 17:56:27 GMT References: <31821@iuvax.cs.indiana.edu> <32029@iuvax.cs.indiana.edu> Organization: Space Telescope Science Institute, Baltimore, MD 21218 Lines: 43 I would like to make a few point that seem clear to me, but apparently aren't clear to others in this discussion. 1) All physical objects are not machines. For example, stones, clouds, flowers, butterflies, and people are not machines. This should be obvious, but some people use the word machine to include all physical objects. Not only is this contrary to ordinary usage, it obscures an important distinction between what is an artifact and what is not. 2) Not all machines are computers. Lamps, screwdrivers, and cars are not computers. 3) There are some activities which can be performed by physical objects and machines which cannot be peformed by computers. Birds can fly and airplanes can fly, but computers cannot fly. Of course, a computer can control an airplane, but this misses the distinction I am trying to make. The distinction is that all computers, as computers, are equivalent to Turing machines. If the computers performs some other activity during its operation than executing a program (for example, flying) it is because the machine which contains the computer is capable of the activity (as airplanes are capable of flying). 4) The simulation of a physical activity by a computer cannot be identified with the physical activity. A computer running a flight simulation program is not flying. 5) Hence, while it may be possible to build a machine that thinks, it does not follow that it will be possible to build a computer that thinks, as not all physical activities can be performed by computers. 6) While there are good reasons to believe that thinking is a physical activity, there are no good reasons for believing that thinking is the execution of a computer program. Nothing revealed either through introspection or the examination of the anatomy of the brain leads to the conclusion that the brain is operating as a computer. If someone claims that it is, the burden of proof is on that person to justify that claim. Such proof must be base on analysis of the brain's structure and not on logical, mathematical, or philosophical grounds. Since even the physical basis of memory is poorly understood at present, any claim that the brain is a computer is at best an unproven hypothesis. Bernie Simon