A friend passed along a recent and very interesting article in The Atlantic by philosopher Stephen Cave who explores the question and, perhaps unintentionally, illustrates how one's worldview influences the philosophical positions one takes.
Here are just a few excerpts from Cave's essay:
In recent decades, research on the inner workings of the brain has helped to resolve the nature-nurture debate—and has dealt a further blow to the idea of free will. Brain scanners have enabled us to peer inside a living person’s skull, revealing intricate networks of neurons and allowing scientists to reach broad agreement that these networks are shaped by both genes and environment. But there is also agreement in the scientific community that the firing of neurons determines not just some or most but all of our thoughts, hopes, memories, and dreams.Throughout his article Cave simply assumes materialism is true. Of course, if it is true then obviously only the material brain can be responsible for our mental activity. But why think materialism is true? Cave never tells us but rather just seems to assume everyone, or at least all intelligent people, accepts it. If, though, it's not true and we do have immaterial minds then it could be that brains and minds work in tandem like the television set and the electromagnetic signals that the set receives and converts into an image. Fiddling with the set will disturb the image, but that doesn't mean that the set is all there is to the production of the image. Cave continues:
We know that changes to brain chemistry can alter behavior—otherwise neither alcohol nor antipsychotics would have their desired effects. The same holds true for brain structure: Cases of ordinary adults becoming murderers or pedophiles after developing a brain tumor demonstrate how dependent we are on the physical properties of our gray stuff.
Many scientists say that the American physiologist Benjamin Libet demonstrated in the 1980s that we have no free will. It was already known that electrical activity builds up in a person’s brain before she, for example, moves her hand; Libet showed that this buildup occurs before the person consciously makes a decision to move. The conscious experience of deciding to act, which we usually associate with free will, appears to be an add-on, a post hoc reconstruction of events that occurs after the brain has already set the act in motion.This is not quite correct, however. What Libet (who himself believed we have free will) showed was that even though electrical activity in the brain precedes our awareness of the need to make a decision, we still have the ability to overrule the decision that the brain has selected for us. (See here)
The challenge posed by neuroscience is more radical: It describes the brain as a physical system like any other, and suggests that we no more will it to operate in a particular way than we will our heart to beat. The contemporary scientific image of human behavior is one of neurons firing, causing other neurons to fire, causing our thoughts and deeds, in an unbroken chain that stretches back to our birth and beyond. In principle, we are therefore completely predictable. If we could understand any individual’s brain architecture and chemistry well enough, we could, in theory, predict that individual’s response to any given stimulus with 100 percent accuracy.This is the contemporary scientific image because many neuroscientists embrace metaphysical materialism. In other words, it's their metaphysics that causes them to embrace this picture, not their science. If one has concluded that everything that exists is comprised of matter and energy then whatever explanation for our cognitive processes one invents will ultimately be based on nothing more than atoms and energy.
The really critical question, then, is whether there are good reasons to accept materialism, but, since materialism is, in fact, a metaphysical preference, that's not a question science can answer. More on Cave's article tomorrow.