X-Message-Number: 8588 Date: Fri, 12 Sep 1997 14:09:25 -0400 From: "John P. Pietrzak" <> Subject: Setting the Limits References: <> Thomas Donaldson wrote: > As for the notion of equivalence, I do hope that John Pietrzak read > and listened to what I said. There is no single definition of > equivalence, there are many depending on what you want to do. The > ideas of Turing about computers use a broad definition of equivalence. > Practical issues raise the validity of much narrower definitions. Uhm, let's see, Cryonet #8549? I'll re-read it again to make sure. But really, the Turing Machine is as abstract as it is for a purpose: it sacrifices many specific real-world aspects of modern digital processors in order to gain wide applicability. The TM captures the notion of computation in practically any digital processor currently conceivable. Whenever you _can_ actually prove something about the properties of a Turing Machine, you can be pretty well certain that the result should hold over all possible computers. [ Later on here, on the Turing Test, I've just gotta disagree: ] > 3. The original Turing test, with limited means by which the > interrogator could even talk with the computer/person on the other > side, fails because it does not take in the full range of behavior > a human being can show. But, what would you do with the additional range of behavior? > Issues of intelligence and its meaning, while I certainly agree > that they are far more vague than most people think, aren't the > central problem with it. W.R.T. the TT, there are no issues of intelligence and it's meaning. The TT says _nothing_ about intelligence. It's a test of mimicry. If you have a *completely indistinguishable* mimic of a human, you still don't know if it's intelligent or not, because the TT doesn't say that mimicry = intelligence! > The central problem is that it operates only with symbols. > > Yes, folks, deep down our brains do not work with symbols. Ok, hang on here. Number one, why do you say symbols are insufficient? Depending on your definition of intelligence, they may be just fine; if you can pass information from one being to another which indicates intelligence, you should be able to use symbols (indeed, have to use symbols) to do it. Number two, deep down, we still don't understand our brains. It's perhaps somewhat arrogant to believe that we can write off any given system as not existing. > [...] when we use symbols, we know their MEANING, which ultimately > cannot be given with other symbols. At this point we reach full-fledged philosophical theorizing. You've stated that symbols are not the bottom-level construct, that they are grounded in meaning. Therefore, you must be saying that meaning is the bottom-level construct, right? Some undefined substance that resides somewhere inside our minds? Or is meaning itself grounded in something else; and if so, how would it differ from symbols? (Of course, this is starting to reach well beyond my area of expertise...) > For that matter, human beings (and other devices like them) will > be subject to the Turing limits. Careful now, the implications of this statement may go against some of what you have stated earlier. I too believe that, ultimately, humans are bound by the constraints of Turing machines. However, this also means that I must believe that humans can be simulated, perfectly, on a Turing Machine, or any other equivalent digital processor (given sufficient time and storage capacity). No other futuristic gadgetry need apply. However, this is an issue of belief rather than science right now, and I suspect most people wouldn't agree with me here. John Rate This Message: http://www.cryonet.org/cgi-bin/rate.cgi?msg=8588