Re: what relation do mathematical models have with reality?

From: Bruno Marchal <marchal.domain.name.hidden>
Date: Tue, 26 Jul 2005 17:11:51 +0200

Le 26-juil.-05, à 04:06, Lee Corbin a écrit :


> Well, all that I ask is that the *basics* be kept firmly in mind
> while we gingerly probe forward.
>
> The basics (basic epistemology, that is) include
>
> 1. the map is not the territory, and perception is not reality


This is ambiguous. A trivial example is that for someone who studies
*maps*, maps are the territory. Also: "perception of x" is not "reality
of x". But perception itself is more probably real (unless we are all
zombies), so perception is a reality (independently of the gap between
perceiving and the things at the origin of perception).


>
> 2. the words we have for things are not the things themselves,
> but only labels


NOT ALWAYS. I agree that *in general* we must not confuse the word and
what they are intended for. But here too we can study the words
themselves, and, with comp, we can even make some non trivial
identification.


>
> 3. we must *not* use basic language and terminology that conflicts
> with that used by twelve-year olds


I agree. It is an important point.
Actually I am willing to believe that we can go much further in that
direction. We should NOT use basic language and terminology that we
are unable to translate in a language interpretable by any Lobian
Machine.


>
>> Russell: For most of us in this list, the 3+1 dimensional spacetime
>> we inhabit,
>> with its stars and galaxies etc is an appearance, phenomena emerging
>> out of constraints imposed by the process of observation.
>
> Right there is the problem. Let's focus on what you are *referring*
> to in your first sentence: "the 3+1 spacetime with its stars and
> galaxies". We must keep clear the difference between what you are
> *referring* to and our observations of it, or our perceptions of it.
> They're not at all the same thing.
>
> So when you use the dread "is" and write "For most of us... the
> spacetime *is* an appearance", we've already gone over the edge.
> No. The spacetime that you probably meant is *not* an appearance,
> and we should not talk about it as if it is an appearance. *It*
> is whatever is out there. Yes, our understanding of it may be poor.
> Yes, it may not be at all as we *think*. In fact, it cannot in
> in any literal sense *be* what we *think*.


Come on. What Russell said was the fact that many in this list could
imagine that the very idea of "out there" could be part of the
perception, like in a simulation (real, virtual or even just
arithmetical but I will not insist too much here).

Besides, please take comp seriously (if only just for one week), but it
makes almost "literally" the sky out there be what we think! Only *we*
denotes something much larger than usual. We, the (hopefully)
consistent Machine.

Please correct me, but I have the feeling you take physicalism (the
doctrine that physics is necessarily the fundamental science, or that
physics cannot be reduced to another body of knowledge) as so obviously
true that we should not even *doubt* about it.

Thanks to your conversation with Stathis, and our last posts, I know
you are ready to tackle the fourth step of the Universal Dovetailer
Argument (UDA) ...

My point is that if we take comp seriously enough then it is not a
matter of choice: physics has to be reducible to computer science, and
this in a verifiable way (already partially verified).

I think it is up to you to find an error in the argument (of course you
can wait someone else find it if you have not the time ;).

The UDA is not technical, and *is* the proof.
Only the translation of UDA in the language of a (Lobian) Machine is
obviously technical (like assembly language can be). The goal of that
translation does not consist in making the UDA more rigorous, but only
more constructive (and indeed it gives the shortest path to derive
physics from computer science).


Bruno

PS And all what I say here is compatible with both the ASSA
Schmidhuberian view (a-la Hal Finney) and the RSSA view (Levy,
Standish, me, ...). Our discussion is internal on how we structure the
OMs. I think (well, some like Schmidhuber explicitly invokes some
physicalist predicate at some points, and I could argue the very notion
of "prior" is basically physicalist, but we have already discussed this
...).

http://iridia.ulb.ac.be/~marchal/
Received on Tue Jul 26 2005 - 11:17:26 PDT

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