mckee@corwin.ccs.northeastern.EDU (George McKee) (06/20/88)
Date: Sat, 18 Jun 88 13:27 EDT From: George McKee <mckee%corwin.ccs.northeastern.edu@RELAY.CS.NET> To: ailist@mc.lcs.mit.edu Subject: Consensual realities are structurally unstable (another comment, better late than never, I hope.) As Pat Hayes points out, the right way to interpret the phrase "consensual reality" is as a belief system held by some group of participants about the nature of the universe. However, given a universe that contains more than one group and group-reality, it's reasonable to look at the origin, scope, and structure of the different systems and evaluate them with respect to each other. Now it's conceivable that you may find two or more systems with equivalent descriptive and predictive power, and with equally compact representations in the minds of the participants, and in this situation you might be justified in saying that there is more than one fundamental reality. But this doesn't seem to be the case, and there is in fact one description of the collective experience of humanity, namely science, that clearly outranks all the alternatives in just about any respect you may wish to examine it, except perhaps promises of present or future happiness. This is not to say that the scientific description of reality is complete or without weak spots, just that it's so much better than the others that it surprises me that people can argue against the primacy of scientific, physical reality and use a computer at the same time. But even leaving the content of a description of reality aside, I think it's provable that a constructive, exterior description of the universe, one that posits a single fundamental reality that generates the thoughts and perceptions of each observer, is more *stable* than an interior one that assumes the primacy of mental activity and doesn't assume a physical origin of thought, and consequently permits the observer to accept the validity of multiple descriptions. That is, as long as both the interior and exterior viewpoints are sensitive to new data, many if not all of the potential realities consistent with the interior view are susceptible to catastrophic reorganizations triggered by single new datums, while the single reality assumed by the exterior view can only be incrementally modified by any single fact. The proof of this is, as they say, "too long for this page", but one part of it rests on the observation, implicit in Turing's proof of universal computability, that a computer can't determine its microcode by executing instructions. That is, a mind can't determine its fundamental principles of operation by thinking. You have to look at the implementation -- the hardware and microcode. For computational minds we'll be sure to know the details of the implementation, because we did the design. For the human mind, designed as it is by the random processes of genetic variation and historical accident, it's very hard to know what aspects of its structure and organization are essential or important, and which ones aren't. But it's clear that we now have tools that are only a quantitative step away from telling us what we need to know about how the brain implements the mind. Those people who say "we have no idea about how the brain works" are just announcing their own ignorance. The best that a mind can do by thought alone is to determine an infinite equivalence class of possible implementations of itself. This is apparently one of the major conclusions of Hilary Putnam's soon-to-be-released book "Representation and Reality." It'll be interesting to read it to find out if he's able to take the next step and show the determination of a unique implementation of each human mind in the brain of each individual member of H. sapiens. I sure hope so... - George McKee NU Computer Science p.s. And you thought I was going to write about Catastrophe Theory. Not today...