I think that anthropic reasoning only works when you have a good model of how you could have gotten into the situation in question.
For the beginning of the universe kinds of questions, as I see it, the options boil down to:
1) Is something vaguely like String Theory correct, in which a near-infinite ensemble of universes with different laws is created at the dawn of time, or continuously across time?
2) Are the laws we observe actually perfectly fundamental, and they just happen to be right?
3) Did some entity pick out these laws?
Anthropic reasoning gives us no reason to go for 2, but it is perfectly happy with 1, since it lets us discard all of the parts of the universe with rules that don’t produce life capable of considering the question.
One of the points that I was trying to make is that you can’t apply anthropic reasoning like that. That is, you need to be comparative, to start with at least two models, then update on your anthropic data. As an analogy, I might be able to give you very good reasons for believing that theory A would explain a phenomena, but if theory B explains it better, then we should go with theory B. There are many cases where we can obscure this by talking exclusively about theory A.
So the question is not does 1) explain the situation well, but does 1) explain the situation better than 3), taking into account things such as prior probabilities.
Update: On second thought, multi-worlds is a pretty good answer when combined with the anthropic principle. I suppose that my argument then only shows that case 2) isn’t a very good explanation.
I think that anthropic reasoning only works when you have a good model of how you could have gotten into the situation in question.
For the beginning of the universe kinds of questions, as I see it, the options boil down to:
1) Is something vaguely like String Theory correct, in which a near-infinite ensemble of universes with different laws is created at the dawn of time, or continuously across time?
2) Are the laws we observe actually perfectly fundamental, and they just happen to be right?
3) Did some entity pick out these laws?
Anthropic reasoning gives us no reason to go for 2, but it is perfectly happy with 1, since it lets us discard all of the parts of the universe with rules that don’t produce life capable of considering the question.
One of the points that I was trying to make is that you can’t apply anthropic reasoning like that. That is, you need to be comparative, to start with at least two models, then update on your anthropic data. As an analogy, I might be able to give you very good reasons for believing that theory A would explain a phenomena, but if theory B explains it better, then we should go with theory B. There are many cases where we can obscure this by talking exclusively about theory A.
So the question is not does 1) explain the situation well, but does 1) explain the situation better than 3), taking into account things such as prior probabilities.
Update: On second thought, multi-worlds is a pretty good answer when combined with the anthropic principle. I suppose that my argument then only shows that case 2) isn’t a very good explanation.
I took it as too-obvious-to-mention that 2 & 3 explain the situation just fine, but have massive complexity penalties.