[extropy-chat] Probability of identity
russell.wallace at gmail.com
Tue Oct 10 11:09:17 UTC 2006
I saw this when rummaging through the archives, and didn't see a reply, and
it's been gnawing at me as the one such paradox I don't have a satisfactory
answer for. I'm going to rephrase it in more vivid terms that I find help
make it clearer:
You're sitting down one evening with a ritual to summon Satan and bind him
to your will, because you're annoyed the Playstation 3 is delayed and you
want one _this_ Christmas, dammit. Unfortunately, you miss a bar over one
variable of the binding ritual.
"Muhahaha, foolish mortal!" mocks Satan. "Now you are mine to do with as I
"Erg... I just wanted a PS3," grumbleth you.
"Too bad. Now being evil and all I'm going to do something nasty to you, but
in accordance with tradition, I will give you a logical chance. So, here are
A: I turn you into a frog.
B: I run off a copy of you. In case you're a threadist, I'll do it atom by
atom, neuron by neuron, symmetrically, with thread of consciousness unbroken
throughout, such that there will be two of you at the end and neither
objectively nor subjectively will it be possible to tell which is the
original and which is the copy (and in case you're a substratist, all copies
will continue to be made of carbon compounds in water just like before, no
uploading into silicon chips), so you should equally expect to be either.
Then I will let one copy go free, but similarly multiply the other into 999.
And then I will take all 999 to hell and make them write essays on
postmodernist literature! Muhahaha!
Now being a reasonable devil, I'll let you think for a little while, then
you have to make your choice."
"Oh crap," says you. "If I get turned into a frog, I won't be able to fulfil
many of my goals. Unless I get kissed by a princess. But princesses these
days are few and far between and mostly not into any variant of rishathra.
So the probability there is much less than 50%. Whereas if I choose option
B, there's a 50% probability that I just get to go free. So I should take
"But," you continue to muse, "let's look at the situation tomorrow in that
event. There will be 1 copy of me free, and 999 undergoing horrible torture.
There will be no objective fact of the matter as to what the copying
sequence was. The only objective fact will be that 0.1% of my instances will
be free and 99.9% will be tortured. Therefore I should estimate a
99.9%probability that I'll be tortured. Compared to that, being turned
frog doesn't sound so bad after all."
I'm assuming for the sake of the thought experiment that you're Homo
economicus, only concerned about what you personally will experience, that
you don't value maximizing copies for its own sake etc; the question is
whether in case B you should estimate the probability that you will be
forced to write essays on postmodernist literature versus being allowed to
go free at 50/50 or 99.9/0.1.
Now to a threadist the first line of reasoning seems correct, the thread of
consciousness splits 50/50 and after that who cares what happens to the
other thread that isn't you? So I'll understand perfectly if threadists
reply "fetchez la vache!".
However, I have other reasons (which I won't bring up again here, that
argument's been beaten so far into the ground as to contribute to landscape
erosion) for disbelieving that philosophy. To us patternists, the second
line of reasoning seems correct; 1 copy of our pattern is free and 999
copies are being tortured.
But intuitively the threadist view seems correct here! There must be a 50%
probability on the first copy that I'll go free. Once I'm subjectively
experiencing myself as being free, how can it then make any difference how
many copies of the tortured pattern are made? I can't suddenly find myself
yanked into Satan's classroom just because more copies outside my light cone
were made, can I?
How do we reconcile intuition with the patternist view?
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