Sapolsky and free will

Much behavior is explainable on purely physical and biological grounds

To answer the basic question “Where did that behavior come from,” Sapolsky develops a standard, systematic approach, laid out in his Biology and Behavior coursebook:

We start off by studying the brain and the nervous system. Beginning to work back in time, we then try to understand further the things that modulate the nervous system, such as environmental triggers, hormones, and perinatal and fetal development. Then working further back, we look at the genetic attributes of the population that an individual comes from. This approach pushes us all the way back to examine what the pressures are of natural selection that sculpted that species.

We all know that some of the things that the body does can be explained in this way and that volition has nothing to do with it; if you drink enough alcohol you are eventually going to pass out whether you want to or not. 

What would be surprising would be if we were able to demonstrate that something about our behavior does not work this way.

The classic example of this kind of hypothesis came from Descartes, who imagined that the human pineal gland somehow (to simplify matters) transformed our spiritual energy into physical action. There is a reason why he said this, of course: even as Descartes famously argued that animals were just elaborate machines, he was trying to rescue some form of human free will from determinism. But as Sapolsky systematically lays out chains of causality from the level of molecular interaction all the way up to human behavior — even behavior that once seemed spontaneous — the cumulative effect is to place the full weight of science and our common sense notions of cause-and-effect against the existence of anything like a Cartesian pineal gland.