Although I already covered this in enough detail to make the point. Let me restate.

Imagine you don't take in enough calcium. As a result you begin to develop hypocalcemia. The lowered levels of blood calcium trigger the release of Parathyroid hormone which in turn stimulates osteoclasts which start breaking down bone and inhibits osteoblasts which are responsible for the sequestration of calcium in bone tissue. As a result calcium goes up, PTH secretion goes down and the normal level of blood calcium is restored.

This is a very basic pathway in the endocrine system. A lot gets done and no decision is made by you as to how it happens. It works to promote homeostasis of blood calcium. The job of this system and most others in the body to one degree or another is to promote a wider homeostasis where everything is kept within safe bounds to keep the organism alive. We find these sorts of pathways all through the body in one form or another, all the way up to the firing of neurons and to the actions of neural synapses which we have so far been able to understand.

There is a lot still to uncover as any neuroscientist will tell you but let me ask you. Is it more likely that there is an entirely new class of system hidden some where inside your brain which exercises some sort of discrete free will in a manner we cannot yet comprehend? Or that the building blocks of the brain are exactly the same sort of homeostatic systems that we see everywhere else not only in humans but in all of DNA based life? Systems that react to a predictable stimuli in a predictable way to produce a predictable result. 

If the second is the case then there really isn't any need to posit the existence of free will in order to explain the behavior. In fact, by doing so we are engaging in a sort of biological appologetics. Of course free will exists, we have just got to find the mechanism for it buried somewhere in the dark spaces we don't yet understand! And hey maybe we will, there will be some sort of Eienstien or Newton like moment in which our understanding is completely overturned and everything turns out the way we all hope. But that is just a hope and I for one am not so certain that the answer isn't more basic and less illuminating than we might wish.

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