Vladimir_Nesov comments on Real-Life Anthropic Weirdness - Less Wrong

24 Post author: Eliezer_Yudkowsky 05 April 2009 10:26PM

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Comment author: Tyrrell_McAllister 06 April 2009 08:16:43PM *  5 points [-]

I get the feeling that there must be an "anthropic weirdness" literature out there that I don't know about. I don't know how else to explain why no one else is reacting to these paradoxes in the way that seems to me to be obvious. But perhaps my reaction would be quickly dismissed as naïve by those who have thought more about this.

The "obvious" reaction seems to me to be this:

The winner of the lottery, or Barack Obama for that matter, has no more evidence that he or she is in a holodeck than anyone else has.

Take the lottery winner. We all, including the winner, made the same observation. No one, including the winner, observed anything unusual. What we all saw was this: someone won the lottery that week. This is not an uncommon event. Someone wins the lottery in many weeks.

Perhaps people are confused because the winner will report this shared observation by saying

  • "I won the lottery this week."

And, indeed, in that regard, the winner is unique. But, in the very way that I formulated this fact, the referent of "I" is defined to be the winner. Therefore, the above remark is logically equivalent to

  • "The winner of the lottery this week won the lottery this week."

That hardly seems the sort of surprising evidence that might lead one to suspect holodecks. Moreover, it's what we all observed. With regards to evidence for holodecks or what have you, the winner is not in a special position.

Maybe people think, "But the winner predicted what the numbers would be beforehand, and he or she then observed those predictions come true. That gives the winner strong evidence for the false conclusion that he or she can predict lotteries."

But that conclusion just doesn't follow. We all observed the same thing: Millions of people tried to guess the numbers, and one (or a few) got them right. That's all that any of us saw. The number of correct predictions that we all saw was perfectly consistent with chance.

If the winner were unaware of all the other people who tried to guess the numbers, then he or she would be in trouble. Then he or she might validly reason "Just one person tried to guess the numbers, and that person got it right. Therefore, that person must have a special ability to predict the numbers." That's the person I pity, someone who had the misfortune to be exposed to extremely misleading observations. But normal lottery winners are not in that position.

I also don't see the asymmetry in the Quantum Theory of Immortality scenario. You and your friend both make the same observation: the version of you in the Everett branch where the gun doesn't go off doesn't get shot. Assuming that you both believe Many-Worlds, you both know that there are scads of branches out there where both your friend and your bullet-punctured remains "observed" (i.e., recorded in their physical structure), the gun's firing. And if you weren't convinced of Many-Worlds, then you will likely conclude that your model of physics is wrong because of the high probability that it assigned to the gun's firing. Rather than conclude that Many-Worlds is true, you will probably throw out QM altogether. (You might do this eventually even if you did go in believing Many-Worlds.) But, again, you have no privileged position over your friend here, because you don't see anything that he doesn't see.

Am I missing something? Are these paradoxes really this easy to dismiss?

Comment author: Vladimir_Nesov 06 April 2009 08:40:22PM *  0 points [-]

I tentatively agree with all the points you make above. This is a general principle: it shouldn't matter where or when the mind making a decision is, the decision should come out the same, given the same evidence. In the case of instrumental rationality, it results in the timeless decision theory (at least of my variety), where the mind by its own choice makes the same decision that its past instance would've precommited to make. In the case of prisoner's dilemma, the same applies to the conclusions made by the players running in parallel (as a special case). And in the cases of anthropic hazard, the same conclusions should be made by the target of the paradoxes and by the other agents.

The genuine problems begin when the mind gets directly copied or otherwise modified in such a way that the representation of evidence gets corrupted, becoming incorrect for the target environment. Another source of genuine problems comes from indexical uncertainty, such as in the Sleeping Beauty problem, the case I didn't carefully think about yet. Which just might invalidate the whole of the above position about anthropics.