Hi Sabine,
Nice essay! I'm a bit skeptical that anything we tend to call "free will" has anything to do with any of this, but you still make many interesting points about strong emergence and reductionism. (For a nice modern take on Free Will, I highly recommend Jenann Ismael's new book, "How Physics Makes us Free". )
Two questions for you:
1) The only vague overlap between our essays is the paragraph where you argue that boundary constraints aren't a counter-example, because in the case of a conducting plate you can replace the boundary constraint with the microscopic details of the plate. But you seemed to imply that the same argument would go through for *cosmological* boundaries. To me, this seems like a very different issue. It's not at all clear that one could talk about the microscopic details of the cosmological boundary in the same way. What would you say to a claim that the cosmological boundary is both fundamental and an example of top-down causation?
2) You finesse the question about the "size" of a quantum system by talking about center of mass energies, which I suppose is fine from an operational perspective. But near the end, when you try to dispute that entanglement is an example of top-down causation, you imply that there is such a thing as the "microscopic constituents" of two entangled particles. What do you have in mind here? We've recently had a conversation about this, and how there's often no way to come up with a spacetime representation of the pieces of an entangled state, so there's really no way to assess whether it's "microscopic" or not, living in a higher dimensional configuration space as it does. For example, for a two-qubit state, there are additional parameters (such as the "concurrence", a measure of entanglement) that don't seem to live anywhere at all, or have any size associated with them. So you might need to sharpen up this argument, using your operational language from before, if you don't want to have to defend and define the two "microscopic constituents" of an entangled state. (Or else help me figure out what those constituents might actually be! :-)
Cheers! -Ken