Re: What Computationalism is and what it is *not*
On 03 Sep 2005, at 20:54, Hal Finney wrote:Okay, I was mostly trying to clarify the terminology. The problem isthat sometimes you use "comp" as if it is the same as computationalism,and sometimes it seems to include these additional concepts of the ChurchThesis and Arithmetical Realism. Maybe you should come up with a newword for the combination of comp (aka "Yes Doctor") + CT + AR. Then youcould make it clear when you are just talking about computationalism,and when you are including the additional concepts. I will think about it, but I do think that CT and AR are just making the YD more precise. Also everybody in cognitive science agree explicitly or implicitly with both CT and AR, so to take them away from YD could be more confusing.Would I meet a computationalist supporting explicitly some negation of CT or AR, I think it is up to him to make that clear because by default CT and AR are accepted. It is just that my conclusion are "enormous" so that I make the assumptions explicit. But actually I have never met someone against CT and AR, at least before I try to communicate the argument.Too much vocabulary can also be confusing. But I will think about it. I use "comp" since 1998. Before, I was using instead "indexical digital mechanism" (indexical for the "I" in "I am a machine" or "I say yes to the doctor").Bruno http://iridia.ulb.ac.be/~marchal/
Re: What Computationalism is and what it is *not*
Bruno writes: I will think about it, but I do think that CT and AR are just making the YD more precise. Also everybody in cognitive science agree explicitly or implicitly with both CT and AR, so to take them away from YD could be more confusing. I think that is probably true about the Church Thesis, which I would paraphrase as saying that there are no physical processes more computationally powerful than a Turing machine, or in other words that the universe could in principle be simulated on a TM. I wouldn't be surprised if most people who believe that minds can be simulated on TMs also believe that everything can be simulated on a TM. (I don't see the two philosophical questions as absolutely linked, though. I could imagine someone who accepts that minds can be simulated on TMs, but who believes that naked singularities or some other exotic physical phenomenon might allow for super-Turing computation.) But isn't AR the notion that abstract mathematical and computational objects exist, to the extent that the mere potential existence of a computation means that we have to consider the possibility that we are presently experiencing and living within that computation? I don't think that is nearly as widely believed. That simple mathematical objects have a sort of existence is probably unobjectionable, but most people probably don't give it too much thought. For most, it's a question analogous to whether a falling tree makes a noise when there's no one there to hear it. Whether the number 3 existed before people thought about it is an abstract philosophical question without much importance or connection to reality, in most people's minds, including computationalists and AI researchers. To then elevate this question of arithmetical realism to the point where it has actual implications for our own perceptions and our models of reality would, I think, be a new idea for most computationalists. Right here on this list I believe we've had people who would accept the basic doctrines of computationalism, who would believe that it is possible for a human mind to be uploaded into a computer, but who would insist that the computer must be physical! A mere potential or abstractly existing computer would not be good enough. I suspect that such views would not be particularly rare among computationalists. Hal Finney
Re: What Computationalism is and what it is *not*
Hal Finney, You say, . . . the Church Thesis, which I would paraphrase as saying that there are no physical processes more computationally powerful than a Turing machine, or in other words that the universe could in principle be simulated on a TM. I wouldn't be surprised if most people who believe that minds can be simulated on TMs also believe that everything can be simulated on a TM. I'm out of my depth here, but this doesn't make sense to me. My understanding is that the Turing Machine is a hypothetical device. If one could be built that operated at faster-than-light or infinite speed, maybe it could, in principle, simulate the universe. However, this isn't possible. Does this mean that the Church Thesis, hence computationalism, is, in reality, false? Norman Samish
Re: subjective reality
Hi Norman, I agree that you can assume that one multiverse exists and that that implies that everything describable exists. But If physical existence is not the same as mathematical existence then there is nothing we can do to verify this. So, this like postulating that a powerless God exists. Saibal - Original Message - From: Norman Samish [EMAIL PROTECTED] To: everything-list@eskimo.com Sent: Saturday, September 03, 2005 09:33 PM Subject: Re: subjective reality Hi Saibal, While my simple mind believes that mathematical existence = physical existence, I do not assume that we owe our existence to the mere existence of the algorithm, not a machine that executes it. To me, the reason that mathematical existence means physical existence is that in infinite space and time, everything that can exist must exist. If it's describable mathematically, then it can exist, somewhere in the multiverse - therefore it must exist. Tegmark claims, for example, that in his Level I multiverse, there is an identical copy of (me) about 10^10^29 meters away. (arXiv:astro-ph/0302131 v1 7 Feb 2003) Norman ~~ - Original Message - From: Saibal Mitra [EMAIL PROTECTED] To: [EMAIL PROTECTED]; [EMAIL PROTECTED] Cc: everything-list@eskimo.com Sent: Saturday, September 03, 2005 7:10 AM Subject: Re: subjective reality Hi Godfrey, It is not clear to me why one would impose constraints such as locality etc. here. Ignoring the exact details of what Bruno (and others) are doing, it all all boils down to this: Does there exists an algorithm that when run on some computer would generate an observer who would subjectively perceive his virtual world to be similar to the world we live in (which is well described by the standard model and GR). The quantum fields are represented in some way by the states of the transistors of the computer. The way the computer evolves from one state to the next, of course, doesn't violate ''our laws of physics''. It may be the case that the way the transistors are manipulated by the computer when interpreted in terms of the quantum fields in the ''virtual world'' would violate the laws of physics of that world. But this is irrelevant, because the observer cannot violate the laws of physics in his world. Also, if you believe that ''mathematical existence= physical existence'', then you assume that we owe our existence to the mere existence of the algorithm, not a machine that executes it. Saibal - Defeat Spammers by launching DDoS attacks on Spam-Websites: http://www.hillscapital.com/antispam/
Re: What Computationalism is and what it is *not*
Hi Norman, A TM in our universe can simulate you living in a virtual universe. If your universe is described by the same laws of physics as ours, then most physicists believe that the TM would have to work in a nonlocal way from your perspective. Is this a problem? I don't think so, because the TM doesn't exist in your universe, it exists in our universe and it doesn't violate locality here. The TM generates your universe in which locality cannot be violated. So, I don't see the problem. Saibal - Original Message - From: Norman Samish [EMAIL PROTECTED] To: everything-list@eskimo.com Sent: Monday, September 05, 2005 08:44 PM Subject: Re: What Computationalism is and what it is *not* Hal Finney, You say, . . . the Church Thesis, which I would paraphrase as saying that there are no physical processes more computationally powerful than a Turing machine, or in other words that the universe could in principle be simulated on a TM. I wouldn't be surprised if most people who believe that minds can be simulated on TMs also believe that everything can be simulated on a TM. I'm out of my depth here, but this doesn't make sense to me. My understanding is that the Turing Machine is a hypothetical device. If one could be built that operated at faster-than-light or infinite speed, maybe it could, in principle, simulate the universe. However, this isn't possible. Does this mean that the Church Thesis, hence computationalism, is, in reality, false? Norman Samish - Defeat Spammers by launching DDoS attacks on Spam-Websites: http://www.hillscapital.com/antispam/
RE: What Computationalism is and what it is *not*
Bruno writes Well, even at step 0 (Yes doctor), if the doctor is honest it will warn you that the artificial brain is a digital device, and I cannot imagine him explaining what that really means in all generality without invoking Church thesis. That's funny. My doctor never explains even how my blood pressure medication works. On the contrary, the surgeons would definitely *not* bring up CT when/if they replace a bundle of neurons with an electronic cable; their only assurances to the patient are whether works or not, and whether I'll feed any pain (besides the bill). Nor, does it seem, does Microsoft or Intel ever use CT in its promotions of various devices for, say, the military. Everyone already knows what computers do (roughly), and what can be expected of them. The accepted *definition* by usage that everyone uses is that it is a *claim* that classical (non-QM) robots could be conscious, that minds could be uploaded into computers. So invent your own term if you don't like how the rest of the world is using of computationalism. Lee
RE: What Computationalism is and what it is *not*
Hal writes That simple mathematical objects have a sort of existence is probably unobjectionable, but most people probably don't give it too much thought. For most, it's a question analogous to whether a falling tree makes a noise when there's no one there to hear it. Whether the number 3 existed before people thought about it is an abstract philosophical question without much importance or connection to reality, in most people's minds, including computationalists and AI researchers. It's true. Most AI researchers and those who (if they were familiar with the term) would consider themselves computationalists do *not* concern themselves with questions about the existence of numbers. To then elevate this question of arithmetical realism to the point where it has actual implications for our own perceptions and our models of reality would, I think, be a new idea for most computationalists. That's for sure. Right here on this list I believe we've had people who would accept the basic doctrines of computationalism, who would believe that it is possible for a human mind to be uploaded into a computer, but who would insist that the computer must be physical! Why, whyever for? Isn't it true that most people don't object to their *physical* destruction because they realize that they'll continue to live on as abstract machines? For sure, those who believe fully in the Universal Distribution don't really care if they get hit by a truck, because after all, their computation will continue anyway---it will even continue in some other physical universe according to the QTI (Quantum Theory of Immortality). A mere potential or abstractly existing computer would not be good enough. I suspect that such views would not be particularly rare among computationalists. Well, I guess they're just not familiar enough with the QTI. But even without QTI, can't Bruno prove that the bitstrings that make you up arithmetically are unaffected by mere trucks? Lee
