Dear Russell and Bruno, Interleaving.

----- Original Message ----- From: "Russell Standish" <[EMAIL PROTECTED]> To: "Bruno Marchal" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Monday, March 08, 2004 7:50 PM Subject: Re: Tegmark is too "physics-centric" On Fri, Mar 05, 2004 at 02:20:54PM +0100, Bruno Marchal wrote: > > >How does COMP entail that I am a machine? I don't follow that step at all. > > > But comp *is* the assumption that I am a machine, even a digital machine. > My last formulation of it, easy to remember is that comp = YD + CT + RA > YD = Yes doctor, it means you accept a artificial digital brain. > (and CT is Church thesis, and RA is some amount of arithmetical realism). > In "conscience et mecanisme" comp is called MEC-DIG-IND, DIG is for > digital, and IND is for indexical. It really is the doctrine that I am a > digital machine, or that I can be emulated by a digital machine. [RS] Yes, in your thesis you often talk about survival under replacement of a digital brain (cerveau digital). Digital simply means "operates with 1s and 0s". Since any analogue value can be represented arbitrarily accurately by a digital signal, this doesn't seem much of a stretch. In your chapter 1, you refer to a "machine universelle digitale, c'est a dire un ordinateur". The English word computer, which is the literal translation of ordinateur, can refer to an analogue computer, which is merely a device for performing computations - it needn't even be Turing complete. The fact that you used the word "universelle" previous does imply Turing completeness, but not that it is equivalent to a Turing machine. After all, I might be concerned if there was some noncomputable part of the brain that was not captured by a Turing machine, but could be built into a digital machine of some kind (eg by accurate copying of the physical layout of the brain). *** [SPK] I think that the key here is something like a 1st person version of a Turing Test: If you can not tell a difference between one's world of experience while in a "meat machine" - brain - and a digital machine then it is not a difference. Substantivalists will try to dispute this but that is a debate for another day. This would seem to require only that there sufficient expressiveness within the digital machine's n-ary representation to encode all of the fullness of all 1st person experiences that whatever kind of "machine" - meat or silicon or whatever - could have. *** [RS] Now I noticed you used the word "indexical". What does this mean? (I tend to skip over terms I don't understand, in the hope that I understand the gist of the argument). Anyway, the upshot of this was that I assumed that COMP was in fact more general that computationalism. In fact I believe the first half of your thesis (chapters 1-4) indeed still hold for this more general interpretation of COMP (namely the necessity for subjective indeterminism etc). True computationalism is perhaps only required for the later sections where you invoke Thaetus's (is that the correct translation of Theetete?) theories of knowledge (connaissance). For here, you need Goedel's theorem, which is applicable in the case of Turing machines. *** [SPK] It seems to me that COMP is more general that computationalism since it seems to include certain unfalsifiable postulations that are independent of computationalism per say, AR, to be specific. My own difficulties with Bruno's thesis hinges on this postulation. I see it as an avoidance of a fundamental difficulty in Foundation research, how to account for the 1st person experience of time if one assumes that Existence in itself is Time-less. > >> Computationnalism is really the "modern" digital version of "Mechanism" > >> a philosophy guessed by early Hindouist, Plato, ... accepted for animals > >> by > >> Descartes, for humans by La Mettrie, Hobbes, etc. With Church > >> thesis mechanism can leads to pretty mind/matter theories. > >> > >[RS] > >If one accepts mechanisms that go beyond the Turing machine, then > >computationalism is a stricter assumption than mere mechanism (which I > >basically interpret as "anti-vitalism"). > > > >I would counter that a Geiger counter hooked up to a radioactive > >source is a "mechanism", yet the output cannot be computed by a Turing > >machine. (Of course some people, such as Schmidhuber would disagree > >with that too, but that's another story). > [BM] > But no mechanism can compute the output of any self-duplication. > With Everett formulation of QM, a Geiger counter is emulable by a turing > machine, and the QM indeterminacy is just a first person comp indeterminacy. > You cannot emulate with a turing machine the *first person* knowledge > he/she gets from looking at the Geiger counts, but no machine can > predict the first person knowledge of a Washington/Moscow self-duplication > either. > *** [SPK] This is somewhere else that I trip over and fall in my thinking of your work, Bruno. Is this "mechanism can compute the output of any self-duplication" a classical version of the "no-cloning" theorem? > Bruno [RS] I agree one can simulate the Schroedinger equation of QM (albeit with irrelevant exponential slowdown). However, mapping this back to your "YD" postulate, this involves the doctor swapping the entire universe, not just your brain. Perhaps you mean that one of the options the doctor has is to upload you into a well crafted digital simulation (by a Turing machine even) of you and your complete environment (a la Matrix). *** [SPK] Does my comment above about how to bridge this gap of emulating a brain and emulating the entire universe? If it does it would seem to dramatically increase the computational power requirements of the emulating computation on top of the exponential slowdown. One technical question I have about this is: if we assume that the emulated universe is finite, what would be the equation showing the required computational power of the emulator given an estimate of the total algorithmic and/or information content of the universe? Additionally, what are we to make of results such as the Kochen-Specker theorem that show that given any quantum mechanical system that has more than two independent degrees of freedom can not be completely represented in terms of Boolean algebra? *** [RS] Reminds me of the option Arthur Dent was presented with by the pandimensional beings (aka mice) when they wanted to mince his brain to extract the question for which the answer was '42'. *** [SPK] Questions like "What is we are "really" pandimensional beings that are only consciously aware of what they are like as "humans?" suddenly have more than a literary meaning. ;-P Kindest regards, Stephen