Julian Sanchez has an excellent discussion of free will, though I think he’s ultimately unpersuasive in convincing me that there isn’t free will.

Of course, the thing about most discussions of free will is that most people don’t have a very good grasp of a definition of free will at all. For my own part, I’m relatively convinced that free will is possible. And the way I define free will, loosely, is “the ability to choose one thing rather than another within the constraints of physical law.”

Now, it so happens that while I think free will exists, this is not the same way as believing that free will is responsible for all human action. Instinct, indoctrination, and DNA account for heaping handfuls of human behavior. Indeed, if history is any guide, I would suggest that free will is a capability of human beings that has to be developed–worked out, like a muscle.

In other words, I agree with Aristotle that humans are largely creatures of habit, and that it takes real effort to actually change those habits. The willingness to do so is part of the development of the will, but it’s hard. Especially as you get older. Frankly, I think the matter deserves study. It’s clear that neuroplasticity exists, and we all know people who have made conscious efforts to embark on radical changes in their lives (the fat kid in high school changes his diet and exercise patterns, etc.). But on the other hand, man, some people hardly ever change at all.

The fact that people, despite making some effort to change, end up falling back into the same patterns is evidence that our “will” isn’t as free as we’d like it to be. (For a terrific examination of this theme, by the way, go rent the entire series of The Sopranos).