I read Scott Aaranson's initial criticism of Hoel's causal emergence paper (which is pretty funny because of things unrelated causal emergence really: "Higher-level causation exists (but I wish it didn’t)": http://www.scottaaronson.com/blog/?p=3294)

I've skimmed the linked article, and will in all likelihood go back to it—but I wonder about some stuff from the conclusion:

> It also provides some insight about the structure of science itself, and why it’s hierarchical (biology above chemistry, chemistry above physics). This might be because scientists naturally gravitate to where the information about causal structure is greatest, which is where they are rewarded in terms of information for their experiments the most, and this won't always be the ultimate microscale.

I don't see how more information existing at higher levels would explain the hierarchical structure of the sciences: saying there's more information at the higher levels is the reason would imply that e.g. we found biology to be more valuable than physics, whereas the actual situation seems to be that we value these levels equally. Maybe that's just a phrasing issues. In any case, it seems simpler that we organize the sciences hierarchically because the human brain organizes information that way.

I also don't see how there being more information at certain levels is necessarily useful: isn't the quality of the information as important or more important than the quantity? But I guess if the it's specifically 'causal' information, there's an implication (at least for the sciences) of ideal quality...