Stathis Papaioannou wrote: > 2008/10/30 Bruno Marchal <[EMAIL PROTECTED]>: > >> The seven first steps of the UD Argument show this already indeed, if >> you accept some Occam Razor. The movie graph is a much subtle >> argument >> showing you don't need occam razor: not only a machine cannot >> distinguish real from virtual, but cannot distinguish real from >> arithmetical either. Many people does not know enough in philosophy >> of >> mind to understand why the movie graph argument is necessary to >> complete the proof, so I rarely insist. Maudlin's 1989 paper can be >> said answering to the "counterfactual- objection" against the MGA >> (Movie-Graph Argument). > > Bruno, I'm not sure why you de-emphasise step 8 of the UDA. The other > steps are relatively straightforward and uncontroversial compared to > step 8. People who encounter the argument will naturally ask, how can > you have a computation without a computer or a mind without a brain? I > think I understand your reasoning (and Maudlin's) here, but it needs > to be spelled out if the UDA is not to be dismissed on the grounds > that it proves nothing about reality, assumed to be at the bottom > level comprised of hard physical objects.

Stathis, you see I cannot doubt about consciousness, so I can doubt only matter, and my research is in big part motivated by explaining what is matter without taking granted it exists or what it can be, i.e. my goal consists in explaining matter from non material entities which I can understand; like numbers and simple sets (of numbers). It took some time for me to realize that most people really take the existence of matter for granted. But then what is it? Despite appearance, physics never relies on the materialist assumption, except in the background, as an excuse for not dwelving into what they take, with Aristotle, as metaphysics. Physical theories are mathematical theories, with conventional and relative "unities". To invoke "matter" as an explanation for actuality or reality seems to me as erroneous as using the notion of God for justifying the creation. At the origin, the Movie Graph Argument (MGA) was an attempt to explain the mind body problem once we assume comp, and to show the difficulties of the notion of matter to the materialists. But your remark is fair enough, and eventually we have to spelled out all the details for having a proof or completely convincing argument. I will try to build an argument developed through little steps; like I have done for the UDA, but note that even for UDA it is rare people tells the step where they stop to understand. We will see. I guess sometimes that people are a bit anxious with those matter and I don't want to push them too much. yet I am very glad you understand it, so perhaps you will be able to help. I will send, in a new MGA thread, a first step. OK. I will go slowly (if only because I am a bit busy). You wrote also: > > 2008/10/30 Bruno Marchal <[EMAIL PROTECTED]>: > >> To make a prediction on the future from the past you have to remember >> the past (or at least some relevant part of the past). If you allow >> (partial) amnesia, it could depend on many things including the type >> of computations allowing the amnesia: it makes almost no sense a >> priori. It would be like asking what is probability to get six >> (subjectively or as first person experience, like we have to do >> assuming comp) when throwing a dice knowing in advance that once you >> have thrown the dice you will forget that you have thrown the dice! >> So I am not sure the question can even make sense. I said to George >> Levy a long time ago (in this list) that all first person >> probabilities in self-multiplication experiments presuppose that the >> level of substitution (of brain material) has been chosen correctly, >> and thus serendipitously given that we cannot known for sure our own >> substitution level. > > Your teleportation thought experiments seem quite straightforward and > intuitive to me: if I am copied to two separate locations, then I > should have a 1/2 first person probability of finding myself in one or > other location. We can assume for the sake of the experiment that the > copying is close enough to perfect, and dismiss the possibility that > the copies will be zombies. So, will the probability of finding myself > in each location still be 1/2 if one of the copies is perfect but the > other is 99% or 50% or 1% faithful, by whatever criterion you care to > define these percentages? Hmmm... Sometime ago I would have refuse to answer this question. I know that for the exact and precise derivation of physics from computer (mathematical) science, we need to be able to answer this, but my point has never been to derive physics from comp, it consists just to explain why, assuming comp, we *have to* derive physics from comp (independently of the difficulty of the task). But ok, perhaps I have make some progress lately, and I will answer that the probability remains invariant for that too. The probability remains equal to 1/2 in the imperfect duplication (assuming 1/2 is the perfect one). But of course you have to accept that if a simple teleportation is done imperfectly (without duplication), but without killing you, the probability of surviving is one (despite you get blind, deaf, amnesic and paralytic, for example). OK? What do you think? Sometimes ago I would have equate total amnesia with death, but I have change my mind on this. What is your opinion on this, doctor? Note also that eventually the measure of uncertainty are not really probabilities but coefficient of credibility. They don't compose transitively. The notion of probability can be used only for the immediate experience, despite they are defined by a weight on, most probably, infinite histories (for not getting paradoxes we have already discussed). - Bruno Marchal http://iridia.ulb.ac.be/~marchal/ --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Everything List" group. To post to this group, send email to [EMAIL PROTECTED] To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/everything-list?hl=en -~----------~----~----~----~------~----~------~--~---