Re: Request for a glossary of acronyms
Bruno Marchal wrote: At 20:17 03/02/04 -0500, Jesse Mazer wrote: Personally, I would prefer to assign a deeper significance to the notion of absolute probability, since for me the fact that I find myself to be a human rather than one of the vastly more numerous but less intelligent other animals seems like an observation that cries out for some kind of explanation. I am not sure about that. Suppose a teacher has 10^1000 students. Today he says to the students that he will, tomorrow, interrogate one student of the class and he will chooses it randomly. Each student thinks that there is only 1/(10^1000) chance that he will be interrogated. That's quite negligible, and (assuming that all student are lazy) none of the students prepare the interrogation. But then the day after the teacher says: "Smith, come on to the board, I will interrogate you". I hope you agree there has been no miracle here, even if for the student, being the one interrogated is a sort of (1-person) miracle. No doubt that this student could cry out for an explanation, but we know there is no explanations... Suppose the teacher and the student are immortal and the teacher interrogates one student each day. Eternity is very long, and there will be arbitrarily large period where poor student Smith will be interrogated each days of that period. Obviously Smith will believe that the teacher has something special against him/her. But still we know it is not the case ... So I don't think apparent low probability forces us to search for an explanation especially in an everything context, only the relative probability of continuation could make sense, or "ab initio" absolute probabilities could perhaps be given for the entire histories. But your example assumes we already know the probabilities. If Smith has two different hypotheses that a priori both seem subjectively plausible to him--for example, "the teacher will pick fairly, therefore my probability of being picked is 1 in 10^1000" vs. "I know my father is the teacher's arch-nemesis, therefore to punish my family I expect he will fake the random draw and unfairly single me out with probability 1", then if Smith actually is picked, he can use Bayesian reasoning to now conclude the second hypothesis is more likely (unless he considered its a priori subjective likelihood to be less than 10^-1000 that of the first hypothesis). This is a better analogy to the situation of finding myself to be a human and not one of the much larger number of other conscious animals (even if we restrict ourselves to mammals and birds, who most would agree are genuinely conscious, the number of mammals/birds that have ever lived is surely much larger than the number of humans that have ever lived--just think of how many rodents have been born throughout the last 65 million years!) Even if I a priori favor the idea that I should consider any observer-moment equally likely, unless I am virtually certain that the probabilities are not biased in favor of observer-moments with human-level complexity, then finding myself to actually be experiencing such an observer-moment should lead me to shift my subjective probability estimate in favor of this second sort of hypothesis. Of course, both hypotheses assume it is meaningful to talk about the absolute probability of being different observer-moments, an assumption you may not share (but in that case the Smith/teacher analogy should not be a good one from your perspective). Another possible argument I thought of for having absolute probabilities as well as conditional probabilities. If one had a theory that only involved conditional probabilities, this might in some way be able to explain why I see the laws of physics work a certain way from one moment to the next, by describing it in terms of the probability that my next experience will be Y if my current one is X. But how would it explain why, when I examine records of events that happened in the past, even records of events before my subjective stream of consciousness began, I still see that everything obeyed those same laws back then as well? Could you explain that without talking about the absolute probability of what type of "universe" a typical observer-moment is likely to percieve himself being in, including memories and external records of the past? Jesse _ Create your own personal Web page with the info you use most, at My MSN. http://click.atdmt.com/AVE/go/onm00200364ave/direct/01/
Re: Request for a glossary of acronyms
Jesse Mazer wrote: > Saibal Mitra wrote: > > > >This means that the relative measure is completely fixed by the absolute > >measure. Also the relative measure is no longer defined when probabilities > >are not conserved (e.g. when the observer may not survive an experiment as > >in quantum suicide). I don't see why you need a theory of consciousness. > > The theory of consciousness is needed because I think the conditional > probability of observer-moment A experiencing observer-moment B next should > be based on something like the "similarity" of the two, along with the > absolute probability of B. This would provide reason to expect that my next > moment will probably have most of the same memories, personality, etc. as my > current one, instead of having my subjective experience flit about between > radically different observer-moments. Such questions can also be addressed using only an absolute measure. So, why doesn't my subjective experience ''flit about between radically different observer-moments''? Could I tell if it did? No! All I can know about are memories stored in my brain about my ''previous'' experiences. Those memories of ''previous'' experiences are part of the current experience. An observer-moment thus contains other ''previous'' observer moments that are consistent with it. But I would expect this consistency to be a matter of degree, because sharing "memories" with other observer-moments also seems to be a matter of degree. Normally we use the word "memories" to refer to discrete episodic memories, but this is actually a fairly restricted use of the term, episodic memories are based on particular specialized brain structures (like the hippocampus, which if damaged can produce an inability to form new episodic memories like the main character in the movie 'Memento') and it is possible to imagine conscious beings which don't have them. The more general kind of memory is the kind we see in a basic neural network, basically just conditioned associations. So if a theory of consciousness determined "similarity" of observer-moments in terms of a very general notion of memory like this, there'd be a small degree to which my memories match those of any other person on earth, so I'd expect a nonzero (but hopefully tiny) probability of my next experience being that of a totally different person. Therefore all one needs to show is that the absolute measure assigns a low probability to observer-moments that contain inconsistent observer-moments. But if observer-moments don't "contain" past ones in discrete way, but just have some sort of fuzzy "degree of similarity" with possible past observer-moments, then you could only talk about some sort of probability distribution on possible pasts, one which might be concentrated on observer-moments a lot like my current one but assign some tiny but nonzero probability to very different ones. In any case, surely my current observer-moment is not complex enough to contain every bit of information about all observer-moments I've experienced in the past, right? If you agree, then what do you mean when you say my current one "contains" past ones? > > As for probabilities not being conserved, what do you mean by that? I am > assuming that the sum of all the conditional probabilities between A and all > possible "next" observer-moments is 1, which is based on the quantum > immortality idea that my experience will never completely end, that I will > always have some kind of next experience (although there is some small > probability it will be very different from my current one). I don't believe in the quantum immortality idea. In fact, this idea arises if one assumes a fundamental conditional probability. Yes, it depends on whether one believes there is some theory that would give an objective truth about first-person conditional probabilities. But even if one does assume such an objective truth about conditional probabilities, quantum immortality need not *necessarily* be true--perhaps for a given observer-moment, this theory would assign probabilities to various possible future observer-moments, but would also include a nonzero probability that this observer-moment would be a "terminal" one, with no successors. However, I do have some arguments for why an objective conditional probability distribution would at least strongly suggest the quantum immortality idea, which I outlined in a post at http://www.escribe.com/science/theory/m4805.html I believe that everything should follow from an absolute measure. From this quantity one should derive an effective conditional probability. This probability will no longer be well defined in some extreme cases, like in case of quantum suicide experiments. By probabilities being conserved, I mean your condition that ''the sum of all the conditional probabilities between A and all possible "next" observer-moments is 1'' should hold for the effective conditional probability. In ca
