Topdown causation takes place as well as bottom-up action, with higher-level contexts determining the outcome of lowerlevel functioning, and even modifying the nature of lower-level constituents.
I think this is a hugely unappreciated fact about the universe. Macroscopic variation can be insensitive to virtually all microscopic variation, in the sense that some small set macroscopic variables obeys some relation without special regard to the particular microstate in existence, e.g., PV=nRT. And yet, interactions that can be described entirely at the macroscopic level may end up causing huge changes to microscopic states.
E. T. Jaynes had an important insight about these sorts of things: if something macroscopic happens reproducibly in spite of no fine control over the microstate, then it must be the case that the process is insensitive to microscopic variation; (no duh, right? But --) therefore we will be able to make macroscopic predictions in spite of having no microstate knowledge just by picking the probability distribution over microstates that maximizes entropy subject to the constraints of our macroscopic knowledge.
Consider what this means for so-called "emergent properties". If a system reproducibly displays some "emergent" property once enough constituent parts are aggregated and the aggregation process is largely or entirely uncontrolled, then we ought to be able to predict the emergence of that property by taking a maximum entropy distribution over the details of the aggregation process. (And if control of some aspect of the aggregation process is important, we can incorporate that fact as a constraint in the entropy maximization.)
And consciousness is sometimes said to be an emergent property of brain processes...
This is a classic "Microsoft help desk" answer: while technically correct, it doesn't really help solve the problem. Predicting via entropy distribution for complex systems is hugely more complicated than other methods, and the only places it can really work are things like the ideal gas law and rubber bands. Put together a bunch of systems capable of exporting entropy to each other and interacting, and you'll see the difficulty ramp up absurdly fast.
In Zombies! Zombies? Eliezer mentions that one aspect of consciousness is that it can causally affect the real world, e.g. cause you to say "I feel conscious right now", or result in me typing out these words.
Even if a generally accepted mechanism of consciousness has not been found yet are there any tentative explanations for this "can change world" property? Googling around I was unable to find anything (although Zombies are certainly popular).
I had an idea of how this might work, but just wanted to see if it was worth the effort of writing.