Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10.1 6/24/83; site umcp-cs.UUCP Path: utzoo!linus!philabs!cmcl2!seismo!umcp-cs!mangoe From: mangoe@umcp-cs.UUCP (Charley Wingate) Newsgroups: net.philosophy,net.math Subject: Mind as Turing Machine Message-ID: <1996@umcp-cs.UUCP> Date: Sun, 27-Oct-85 01:08:05 EST Article-I.D.: umcp-cs.1996 Posted: Sun Oct 27 01:08:05 1985 Date-Received: Thu, 31-Oct-85 21:12:55 EST References: <859@whuxlm.UUCP> <10810@ucbvax.BERKELEY.EDU> Organization: U of Maryland, Computer Science Dept., College Park, MD Lines: 23 Xref: linus net.philosophy:2670 net.math:2070 There are a number of reasons why I doubt that the mind is in fact like a turing machine. As James Lewis pointed out, neurons are essentially analog devices; they typically respond to input *levels* rather than to descrete stimulae. If this holds up in general, it means that the state space of the mind is essentially continuous. THe brain also has a lot of analog inputs, posing similar problems with respect to the "tape". At the neural level, one typically sees random behavior. Increasing stimulae tend to increase or decrease the rate or probability of firing, but the action is distinctly unlike the firing structure of a computer. State transitions would seem therefore to be probabilistic. Lastly, it's certainly clear that we cannot now model even moderately small portions of the mind through computers. I think it is reasonable to ask those who wish to assert the turing machine-ness of the mind need to show some method by which the mind can be translated into an equivalent turing machine, even if this translation is computationally infeasible (which is indeed likely). Without such an algorithm, I think there is reasonable cause not to accept the hypothesis. Charley Wingate