Excellent post.
There are a few examples of non-emergence. For example, if we tessellate many small equilateral triangles to create a larger equilateral triangle, the resulting figure will not show any emergent properties.
Outside of mathematics, though, the concept is vague and I can't see much use for it as applied to specific phenomena.
Eliezer, whatever it is you were getting at in your comment, it was waaay over my head. When I searched on Wikipedia for Big World, I got an album by Joe Jackson. When I looked for Everett branches, I found an intriguing article about the Piscataquog River. Could you point me to some further reading? I hate to feel left out of the loop here.
Conchis and Nick, I should have explained my position more clearly. As an atheist myself, I have come to the conclusion that my children will find the ability to think more useful than an arbitrary set of rules that they have been conditioned to follow. The virtue of Santa is that it is a belief they will inevitably question and learn from, while an outspoken conscience will only cloud their ability to reason when they have to make important choices that will determine their future levels of happiness. While you might be able to convince me empirically tha...
When the stakes are high enough I one-box, while gritting my teeth. Otherwise, I'm more interested in demonstrating my "rationality" (Eliezer has convinced me to use those quotes).
Perhaps we could just specify an agent that uses reverse causation in only particular situations, as it seems that humans are capable of doing.