Path: utzoo!attcan!uunet!cs.utexas.edu!rutgers!aramis.rutgers.edu!athos.rutgers.edu!nanotech From: dmo@turkey.philips.com (Dan Offutt) Newsgroups: sci.nanotech Subject: A fallacy: That which evolved can be rationally designed. Message-ID: Date: 30 Jun 89 02:43:10 GMT Sender: nanotech@athos.rutgers.edu Organization: Philips Laboratories, Briarcliff Manor, NY Lines: 53 Approved: nanotech@aramis.rutgers.edu > ... The brain is not magic. If it can evolve, it can be >purposely designed. There can be no credible refutation of this logic. The proposition "if X can evolve via biological evolution, then X can be purposely designed" is generally false. The human brain or immune system might be copied or imitated, but neither human beings nor "fast" AI could possibly design such systems. The proposition is false for two reasons. First, purposeful design presupposes a design problem definition. We know very little about the design constraints for biological systems. The human brain has been shaped by gravity, the ratio of oxygen to nitrogen in the atmosphere, the availability of various raw materials, the capabilities of various predators, evolutionary pressures to economize on resource consumption, and innumerable other influences that we do not understand well enough or are not even aware of. Most of the constraints that shaped the human brain are unknowable in principle because most acted in the distant past, and information about those influences has been lost. For example, the structure of the human brain today may reflect, in some subtle way, the predatory capabilities of saber-tooth tigers, which are now extinct. Saber-tooth tigers are just one influence out of trillions. In short, systems that evolved by biological evolution cannot be designed by people or AI because it is impossible to specify more than a minute fraction of the design constraints. It may be possible to *copy* or *imitate* these evolved systems (as Mr. Drexler points out), but that is not the same thing as designing them. The second reason the proposition is false is that all human designers and all "fast" AI systems put together will never collectively possess the parallel "computational resources" that biological evolution has had to work with. Moreover, biological evolution has been searching for more-viable forms of life for billions of years. Presumably, those who argue that evolved systems could be designed do not have in mind billion-year-long design processes. The products of biological evolution conservatively cost Nature at least trillions of billions of processor years. (If there have been at least a few trillion living things -- each representing a "processor" -- on earth continuously for a billion years.) And this characterization ignores both the complexity of individual organisms and the nonliving environment around all of these creatures. Human designers and "fast" AI over the next 1000 years will not amount to anywhere near a trillion billion processor years. So the raw computational power available to design processes over the next 1000 years is an insignificant fraction of the raw computational power that biological evolutiuon comsumed to produce today's population of life on earth. Thus there isn't enough time available in the next 1000 years to design the human brain, even if the design constraints could all be specified. Dan Offutt dmo@philabs.philips.com