Responding with only limited time to do so to a very interesting discussion prompted by a Bryan Caplan post:
Obviously, indeterminism (i.e. developmental noise making identically-gened twins different from each other) does not satisfy as an explanation of free will. The weather system does not have free will. Need to look elsewhere.
Just to point to a couple of insights from Daniel Dennet in Freedom Evolves.
1. If humans truly do have a kind of free will that other animals (and inanimate entities) don’t, it seems likely that it’s related to another unique ability: the ability to explain our reasons–to others and to ourselves. So the cognitive machinery associated with language could be key to this understanding.
2. Somebody that he cites (don’t have time to look it up) suggests that consciousness and (the impression of) free will evolved essentially as a user interface for a very complex machine. That’s not fully satisfying, because it leaves the “user” intact and separate from the very thing that we think of as “us.” In our case–if this idea is safe–the user *is* the interface (or vice versa).
Sorry, just loose ideas, loosely presented. But they’re both important pointers in my ongoing thinking on the subject.