The act of doing something involves two things:
- Assumption of a posture appropriate to the action.
- Performance of the action (or not).
The assumption of posture is "involuntrary" in that most people are not aware when it happens. The performance of the action is "voluntrary", and the choice to perform the action or not gives rise to the misleading sensation we call free will.
(Alexander technique is all about conscious control of the assumption of posture, and especially about inhibiting the assumption of habitual bad posture.)
If this seems a mundane, everyday definition of "free will", well, isn't "free will" something we experience every day?
A person (who has not studied Alexander technique, or equivalent) can have their sensation of free will overridden by giving them a strong expectation that they are going to assume some particular posture, that assumption of posture constituting an action of itself. Example: rest your arm loosely at your side, a little out from your body. Now imagine it rising (without actually deciding to make it rise).
This is a possible model for the phenomenon of demonic possession (SBS showed John Safron undergoing a rather good example of this recently).
Free will suddenly seems like a cheap parlour trick, which opens a whole can of worms about personal responsibility that i shall discuss at a later date. (Personal responsibility does still make sense, under certain reasonable assumptions. It only fails if there is a God who possesses (very near) infinite computing power.)