>>Jonathan Colvin writes: >> >>>While I'm a supporter of Tegmark's Ultimate Ensemble, I >think it is by >>>no means clear that just because everything that can happen does >>>happen, there will necessarily be a world where everyone becomes >>>omniscient, or lives for ever, or spends their entire life >dressed in a pink rabbit outfit. >>>"Everything that can happen does happen" is not synonymous with >>>"everything we can imagine happening does happen". Worlds where we >>>live forever or become omniscient or are born dressed in a >pink rabbit >>>suit may not be *logically possible* worlds. Just as there >is no world >>>in the multiverse where 2+2=5, there may be no worlds in the >>>multiverse where I live forever or spend my entire life >dressed in a pink rabbit suit. >>> >>>Jonathan Colvin >>> >>I don't see this at all. It is not logically possible that there is a >>world where 2+2=5 (although there are lots of worlds where everyone >>shares the delusion that 2+2=5, and for that matter worlds where >>everyone shares the delusion that 2+2=4 while in actual fact 2+2 does >>equal 5), but how is it logically impossible that you live your whole >>life in a pink rabbit suit? If anything, I would rate such >worlds as at >>least on a par with the ones where pigs fly, and certainly >more common than the ones where Hell freezes over. >> >>--Stathis Papaioannou > >Brent: But what does "logically possible" mean? Logic is just some >rules to prevent us from contradicting ourselves. Is it >logically possible that, "Quadruplicity preens cantatas."? Is >it logically possible that the same object be both red and >green? Once you get beyond direct contradiction (e.g. >"Quadruplicity does >*not* preen cantatas") you have to invoke semantics and some >kind of "nomologically possible". Then, so far as anyone >knows, we're back to "physically possible" and even that is >ill defined. The whole concept of "possible", beyond narrowly >defined circumstances, is so ambiguous as to be worthless.
I think we're assuming Tegmark's UI here, so "physically possible" and "logically possible" means the same thing. Jonathan Colvin