>>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

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