Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!uunet!samsung!zaphod.mps.ohio-state.edu!mips!apple!oliveb!amdahl!pacbell!osc!jgk From: jgk@osc.COM (Joe Keane) Newsgroups: comp.ai Subject: Re: Can Machines Think? Keywords: causality, finiteness, randomness, robustness Message-ID: <1754@osc.COM> Date: 22 Dec 89 23:52:28 GMT References: <31821@iuvax.cs.indiana.edu> <4689@itivax.iti.org> <013Y02gH77ra01@amdahl.uts.amdahl.com> Reply-To: jgk@osc.osc.com (Joe Keane) Organization: Object Sciences Corp., Menlo Park, CA Lines: 30 In article <013Y02gH77ra01@amdahl.uts.amdahl.com> kp@amdahl.uts.amdahl.com (Ken Presting) writes: >If we want to claim that we've accurately modeled the >computational power of the brain by demonstrating that our model is >faithful to the causal interactions in the brain, we're stuck with >modeling the details (including thermal motion) down to whatever level a >critic might demand. This is not true. The concept of an exact simulation may be theoretically interesting, but has nothing to do with AI. The important question is, what level of simulation is necessary to pass the Turing test. I think it is necesary to model different parts of the brain, but not to worry about the exact distribution of potassium ions. If you believe that it must be exact down to the incoming cosmic rays, i don't know what to say. >I'm objecting that it is physically >impossible to make an adequate model. If we could let the model crank >as long as it needed before responding (ie relax the real-time constraint) >then my argument would not hold. The model would eventually converge >close enough to the real system to be indistinguishable. But that won't >pass the Turing test. If i'm not mistaken, you're arguing that it takes an arbitrarily large amount of computation to do an acceptable simulation. I don't believe this at all. Let's perform a thought experiment. I'll make a copy of the universe (that's why it's a thought experiment) and then remove an electron in your clone's brain. This should not cause a severe change in your clone, but since the brain is chaotic, this may cause him to do something differently than the original you. However, despite the fact that you and your clone are now different, there is no way to tell which is the `real' you.