The Frontal Cortex

My last post on neuroscience and free will generated lots of interesting comments. Please check them out. But I think a few readers misunderstood my ambition. It's easiest to begin by saying what I wasn't trying to do: I wasn't trying to construct a philosophically sound defense of free will (I'm not sure such a thing is possible), or reflect on quantum indeterminacy, or get into a metaphysical debate about the material causality of everything. If you believe, ala Laplace, that the world is governed by a discrete set of material rules (as I do), then, of course, freedom doesn't really exist. We're all just matter, blessed with the illusion of being something more. If Laplace's demon were possible - if we really could know everything about everything - then it's hard to imagine how that demon could not predict the future, and make our freedom obsolete.

Of course, that demon is a thought experiment. We will never know everything about anything. (See Maxwell and Heisenberg for the physical details.) So, in that sense, freedom is a necessary result of our ignorance. It might be an illusion, but it's an illusion that will always remain with us, at least for many more centuries. (I'm sure we'll implode the planet before we disprove our free will.)

So those are my caveats. That said, I also groan when I read articles like the one I referenced in The Economist, which uses an extreme example of a deterministic disease (like a brain tumor in the orbitofrontal cortex) to argue that our free will is somehow endangered by the new knowledge of neuroscience. In fact, I believe that neuroscience, at least so far, has made our instinctual belief in free will less absurd. Fifty years ago, there were two basic schools of thought on the brain: The first school was the genetic determinist school, which argued that the mind is just a by-product of its genetic program. Your fate is fixed at birth. The second school was the behaviorist school, which was, in it's own way, just as deterministic. The mind was nothing but a network of conditioned instincts. We were completely free to be entrapped by our environment.

Since then, things have gotten much more interesting and complicated. Neural plasticity demonstrates that our brain isn't set at birth, or at any moment thereafter. You always have the power to change your own neuronal connections, to rewire yourself. (Of course, if you really believe in some sort of cosmic determinism, then your experience is just as determined as your genes. While that's theoretically possible - perhaps even likely - it's not something that keeps me awake at night. What would be troubling, however, is if we were strongly genetically determined, since that would demonstrate that our free will is seriously bounded, and bounded in ways that biology could easily describe.) So yes, I still think plasticity is an affirmation of our potential freedom. Think of it this way: if our mind wasn't plastic, we would be much less free.

As for disorder. . .I never meant to imply that our jumping genes, or developmental noise, or genetic drift, or stochastic gene expression, are random in some numinous, inherently mysterious sort of way. Laplace's demon could figure out what was going on, and tease out all the "causes" behind our apparent cellular disorder. That said, I think many biologists have been surprised by just how much stochasticity there is inside living organisms. We aren't a simple input-ouput machine, and our cells play dice all the time. We used to think that the closer you got to the bottom of everything - to life at its most essential and reductionist - the more ordered and neat everything would appear. In other words, we would see that our "elbow room" is an emergent illusion. But that's not the case. When you drill down to the level of molecular biology that randomness is still there. In fact, it's more apparent then ever. And I'm not even going to mention the quantum world because, frankly, it makes no sense.