I was going to make about the same objection steven makes—if you take this stuff (MWI, anthropic principle, large universes) seriously as a guide to practical, everyday ethical decision-making, it seems to lead inexorably to nihilism—no decision you make matters very much. That doesn’t sound at all desireable, so my instinct is to suspect that there is something wrong either with the physics ideas, or (more likely) with the way they are being applied. But maybe not! Maybe nihilism is valid, but then why are we bothering to be rational or to do anything at all?
But what could NP-hardness possibly have to do with the Anthropic Principle? Well, when I talked before about computational complexity, I forgot to tell you that there’s at least one foolproof way to solve NP-complete problems in polynomial time. The method is this: first guess a solution at random, say by measuring electron spins. Then, if the solution is wrong, kill yourself! If you accept the many-worlds interpretation of quantum mechanics, then there’s certainly some branch of the wavefunction where you guessed right, and that’s the only branch where you’re around to ask whether you guessed right! It’s a wonder more people don’t try this…
Now, if you accept the NP Hardness Assumption (as I do), then you also believe that whatever else might be true of the Anthropic Principle, the previous two examples must have been incorrect uses of it. In other words, you now have a nontrivial constraint on anthropic theorizing:
No application of the Anthropic Principle can be valid, if its validity would give us a means to solve NP-complete problems in polynomial time.
mtraven,
Why we are “bothering to be rational or to do anything at all” (rather than being nihilists), if nihilism seems likely to be valid? Well, as long as there is a chance, say, only a .0000000000000001 chance, that nihilism is invalid, there is nothing to lose and possibly something to gain from assuming that nihilism is invalid. This refutes nihilism completely as a serious alternative.
I think basically the same is true about Yudkowsky’s fear that there are infinitely many copies of each person. Even if there is only a .0000000000000001 chance that there are only finitely many copies of each of us, we should assume that that is the case, since that is the only type of scenario where there can be anything to gain or lose, and thus the only possible type of scenario that might be a good idea to assume to be the case.
That is, given the assumption that one cannot affect infinite amounts by adding, no matter how much one adds. To this, I am an agnostic, if not an atheist. For example, adding an infinite amount A to an infinite amount A can, I think, make 2A rather than 1A. Ask yourself which you would prefer:
1) Being happy one day per year and suffer the rest of the time of each year, for an infinite number of years, or
2) The other way around?
Would you really not care which of these two would happen?
You would. Note that this is the case even when you realize that a year is only finitely more than a day, meaning that each of alternatives 1 and 2 would give you infinitely much happiness and infinitely much suffering. This strongly suggests that adding an infinite amount A to an infinite amount A produces more than A. Then why wouldn’t also adding a finite amount B to an infinite amount A produce more than A? I would actually suggest that, even given classical utilitarianism, my life would not be worthless just because there are infinitely much happiness and infinitely much suffering in the world with or without me. Each person’s finite amount of happiness must be of some value regardless of the existence of infinite amounts of happiness elsewhere. I find this to be plausible, because were it not for precisely the individual finite beings with their finite amounts of happiness each, there would be no infinite sums of happiness in the universe. If every single one of all of the universe’s infinitely many, each finitely happy, being’s happiness were worthless, the infinite sum of their happiness would have to be worthless too. And that an infinite sum of happiness would be worthless is simply too ridiculous a thought to be taken seriously—given that anything at all is to be regarded valuable, an assumption I concluded valid in the beginning of this post.
I was going to make about the same objection steven makes—if you take this stuff (MWI, anthropic principle, large universes) seriously as a guide to practical, everyday ethical decision-making, it seems to lead inexorably to nihilism—no decision you make matters very much. That doesn’t sound at all desireable, so my instinct is to suspect that there is something wrong either with the physics ideas, or (more likely) with the way they are being applied. But maybe not! Maybe nihilism is valid, but then why are we bothering to be rational or to do anything at all?
Scott Aaronson’s objections might carry more weight:
mtraven, Why we are “bothering to be rational or to do anything at all” (rather than being nihilists), if nihilism seems likely to be valid? Well, as long as there is a chance, say, only a .0000000000000001 chance, that nihilism is invalid, there is nothing to lose and possibly something to gain from assuming that nihilism is invalid. This refutes nihilism completely as a serious alternative.
I think basically the same is true about Yudkowsky’s fear that there are infinitely many copies of each person. Even if there is only a .0000000000000001 chance that there are only finitely many copies of each of us, we should assume that that is the case, since that is the only type of scenario where there can be anything to gain or lose, and thus the only possible type of scenario that might be a good idea to assume to be the case.
That is, given the assumption that one cannot affect infinite amounts by adding, no matter how much one adds. To this, I am an agnostic, if not an atheist. For example, adding an infinite amount A to an infinite amount A can, I think, make 2A rather than 1A. Ask yourself which you would prefer: 1) Being happy one day per year and suffer the rest of the time of each year, for an infinite number of years, or 2) The other way around? Would you really not care which of these two would happen?
You would. Note that this is the case even when you realize that a year is only finitely more than a day, meaning that each of alternatives 1 and 2 would give you infinitely much happiness and infinitely much suffering. This strongly suggests that adding an infinite amount A to an infinite amount A produces more than A. Then why wouldn’t also adding a finite amount B to an infinite amount A produce more than A? I would actually suggest that, even given classical utilitarianism, my life would not be worthless just because there are infinitely much happiness and infinitely much suffering in the world with or without me. Each person’s finite amount of happiness must be of some value regardless of the existence of infinite amounts of happiness elsewhere. I find this to be plausible, because were it not for precisely the individual finite beings with their finite amounts of happiness each, there would be no infinite sums of happiness in the universe. If every single one of all of the universe’s infinitely many, each finitely happy, being’s happiness were worthless, the infinite sum of their happiness would have to be worthless too. And that an infinite sum of happiness would be worthless is simply too ridiculous a thought to be taken seriously—given that anything at all is to be regarded valuable, an assumption I concluded valid in the beginning of this post.