>Gilles Henri wrote >>I suspect that the comp hypothesis would in fact favour the solution where >>there is actually no external world at all, but only your (for me, my!) >>mind, because it is much shorter to describe ONLY a brain state than the >>whole Universe surrounding it, although perfectly equivalent regarding our >>sensations. So no world, no friends and no physical laws. We would be back >>to some kind of solipsism, which has been known for a long time to be >>unprovable and undisprovable- just desperately useless. > > >The comp hypothesis favour indeed a solution where there is no external >world at all, nor even any material (whatever it means) brains. > >But that is exactly why I say: > >"We can find ourselves ONLY in those structures which are relatively >numerous, not to survive but to REMAIN WITH OTHERS and a (relatively) >stable environment."

## Advertising

If you admit that the others and the external environment do not really exist, it is difficult to understand why "they" (more precisely, the representation we have from them) should obey precise laws, even statistical. That's what I tried to develop in the next paragraph. >>Even if we are made of this matter, precise >>mathematical laws are not required to make an organized system work: >>civilizations are made of individuals, and they are well structured despite >>the absence of a good mathematical description of each individual. > >OK. What is the point ? The point is that I don't see what should oblige the matter to obey precise laws, if we are not "really" made of it. In other words, why should a "conscious computation" exist only if it implements some representation of mathematical laws? As a matter of fact, most of our conscious activity does NOT rely on mathematical laws (or mathematical representations of physical laws). For me it proves that the representation of physical laws is not NECESSARY to consciousness. It could be then a question of probability, but I don't see why the number of computations implementing precise physical laws should be much greater than the number of computations not implementing then - in fact I would think just the opposite. > >In short the computationnalist (objective) idealism protect us from the >solipsism (subjective idealisme). > >In fact it is not true that the description of ONLY one brain is much >shorter than than the description of the whole Universe surrounding it, >because DeWitt-Wheeler equation, or any UD (universal dovetailer >algorithm) are compressed description of all possible universes and all >possible self-aware substructures in there. I would think that the "UD" is much larger than the DeWitt-Wheeler equation, so it can describe also a huge number of universes without any reasonable relationship within it. I'll try to put it in more quantitative form. I assume I can give a "measure" of the set of possible Universes and separate it into three classes: A : the subset of universes without conscious beings B : the subset of universes containing SAS apparently observing a environment without physical laws. C : the subset of universes containing SAS apparently observing a environment with physical laws. It seems that we live in a C-Universe. Why? I guess (I may be wrong) that if you POSTULATE the existence of a reality obeying physical laws, you could hope to demonstrate m(A)>>m(C)>>m(B), because it is very improbable that conscious beings doing repeated physical experiments would be unable to unveil the existence of physical laws (for example by finding systematically very improbable results where the statistical distributions predicted by QM are never recovered). The observation of A is excluded by the (generalized) anthropic principle, so we explain satisfactorily why we see "C". However, I think that the "everything computable is realized" hypothesis would predict m(A)>>m(B)>>m(C), and so the reason why we are in C is much more mysterious with this hypothesis. Of course if you think you can justify also m(C)>>m(B) with comp, it would have the bonus to explain why physical laws exist (which must be postulated in the first stage), but I am really not convinced of that. Gilles