FROM ROBERT LAWRENCE KUHN, HOST AND CREATOR OF CLOSER TO TRUTH: If it seems perfectly obvious that your will is free, that “you” are able to decide and choose as “you” quite please, then it seems perfectly clear that you don’t get it. Free will is a huge problem.
I’d never thought “free will” to be a problem. If I want to walk, I walk; sit, I sit.
Here’s the problem. Since every physical event has a prior and sufficient cause, then every current movement of atoms is caused by some prior movement of atoms, including all those atoms that compose all those neurons in my brain that “decide and choose” to walk or sit.
What’s the alternative? That physical events can happen without prior and sufficient cause? That seems immediately wrong because it would limit regularities in the world, make laws capricious, obviate science.
Where then free will? Can nonphysical spirits or souls be saviors? That’s what most theists assume. But spirits and souls have their own problems: How on earth does a nonphysical substance interact with a closed physical world?
What then free will? The question is more fundamental than I’d ever imagined.
To Peter van Inwagen, a philosopher at the University of Notre Dame, free will can be characterized by an appeal to the simple word “able.” If one is able to do this and able to do that, and assuming it is not possible to do both this and that jointly, then one has free will. He defines “determinism” as the thesis that the past up to a given moment determines the one unique way that the world is going to go on after that moment. If one takes together all the laws of nature or physics, such as the conservation of energy, gravitational laws, electromagnetic laws, and the like—the real, deep, underlying, most fundamental laws—the metaphysical thesis of determinism, given those laws, allows only one possible future that is consistent with the way things are at present. One is not able to do this or that. So it seems that free will isn’t compatible with determinism.
If determinism isn’t compatible with free will, van Inwagen continues, the implication is that we’re able to do only exactly those things we do. Of course, we have the strong conviction that we could have done other things, that we were able to do things other than those that we did, but, if determinism isn’t compatible with free will, that conviction must be misleading, and free will must be an illusion.
Van Inwagen frames the free will problem provocatively: Free will is either incompatible with determinism or it’s compatible with determinism—and you can prove both propositions wrong! Now, suppose that free will is both incompatible with determinism and incompatible with indeterminism. Since determinism and indeterminism are the only two possibilities, free will is now incompatible with every possibility, so it’s impossible. But, van Inwagen concludes, “it would be a greater mystery if there were no free will.”
Since determinism is the case in which every event is caused completely by a previous event, is determinism compatible or incompatible with free will? This is the critical question.
My first feeling was: No, determinism cannot be compatible with free will.
But then what?
No determinism? What then the physical world?
No free will? What then our intuition?
Free will seems simple, but the more one thinks about it, the more complex it becomes.
John Searle, a leading philosopher of mind at the University of California, Berkeley, calls the problem of free will “something of a scandal in philosophy.” As Searle puts it, “The reason that we have a special problem about free will is that we have inconsistent views, each of which is supported by what are apparently overwhelming reasons. The reason for believing that we have free will is we experience it every day. We have the experience of conscious, rational decision-making, and we have the experience that the decisions were not themselves forced by antecedently sufficiently causal conditions. We can’t shake off the conviction of free will.”
But on the other side, Searle continues, “we’ve got an overwhelming amount of evidence that everything that happens has an explanation in terms of causally sufficient conditions.” In the natural world, in principle, we can always tell a story or explain a mechanism for why things happen the way they do, and since “human behavior is part of the natural world, it looks like it ought to be explained in terms of causally sufficient conditions.”
Searle states that not only are the two assertions, free will and determinism, incompatible, but “it’s hard to see how we could give up on either of them.” We can’t kill off either one. We’re stuck with both. And they’re not compatible. That’s the mystery.
Free will is no mystery to Daniel Dennett, the distinguished philosopher at Tufts University. Nor is he disturbed by arguments that free will and determinism are not compatible.
First of all, Dennett asserts that “for 2,000 years or more, people have been looking in the wrong place. They’ve been looking at physics, determinism and indeterminism in physics. They should have been looking at biology because the key to free will is recognizing that free will is a biological-level phenomenon. It’s not a physics-level phenomenon. We are freer than our parts. Our parts don’t have free will. But we do.”
But how could that possibly be, without adding something novel, something mysterious? How can free will be made compatible with determinism?
Dennett’s move is not to show that our actions aren’t determined, but rather to show that our actions are not inevitable.
Say what? It would seem that if the future is determined it is inevitable. So what does Dennett claim the word “inevitable” adds?
Dennett says “inevitable means unavoidable.” So then we have to understand what “avoiding” is, he says, which brings in the biological dimension. “Because what’s happened on this planet over the last 4 billion years has been an explosion of avoiding: avoiding dissolution, avoiding being eaten, avoiding starving to death. What evolution has done is designed organisms that do avoiding. How do you avoid something? By anticipating it and then taking corrective measures. Simplest case: incoming brick. You see it, you duck: You avoid it. But suppose you were determined to duck. Well then the brick was never going to hit you. It just seemed as if it was going to hit you. What we have to understand is that free will is our capacity to see probable futures, futures that seem like they’re going to happen, and see them in time to take steps so that something else happens instead.”
Dennett adds that while “you can’t change the past, you can’t change the future either. But what you can do is change what you thought the future was going to be into something else, even though it’s all determined. Biological creatures are determined by the evolutionary process to become better and better avoiders.”
In trying to understand Dennett’s argument, I suggested that his definition of free will seemed impoverished, at least compared with conventional descriptions. He agreed: “I think we have to recognize that there are varieties of free will.” As for “the traditional varieties,” Dennett says, “who cares whether we’ve got them?” The varieties of free will “worth wanting,” he states, are “perfectly compatible with determinism.”
So Dennett’s determinism erodes some of the comfortable notions of “free will” because everything we do is “determined” by the underlying physics of our brains and its environment. Even so, Dennett says, because biological creatures have learned how to avoid bad things, nothing is “inevitable.”
All is determined? But not inevitable? I’ll have to ponder that.
Maybe we’ve pushed philosophy as far as it can go? I check with some other friends.
Psychologist Susan Blackmore, a former parapsychologist turned active skeptic, argues that “there can’t be free will in the traditional sense. When you see how the brain works, how information flows through the brain, there’s no place for free will. So let’s give up on it!”
California Institute of Technology brain scientist Christof Koch, a pioneer in discovering the neural correlates of behavior, says, “I’m ambivalent about free will. Right now, I don’t see how in a physicalist [purely material] universe, free will can survive. On the other hand, I have this profound feeling of free will.” According to Koch, “Almost by definition, if you’re not a dualist, physicalism is all there is: All that exists are space and time, energy and mass and fields of force, which means, of course, there’s no free will. If you’re not a dualist, I do not see where free will could come from because there’s nothing else except blind chance and necessity.”
What do I think? 1) My will is fully free. 2) Free will is not an illusion. 3) Free will is not compatible with determinism. If I cannot do otherwise, no matter the philosophical maneuverings, I’m sorry, my will is not fully free.
What would it take for my will to be fully free? Nothing less than a causal “gap” across which prior physical forces could not leap, at least not with absolute certainty. Somewhere the chain of deterministic events must be broken. It only takes one place.
But that, too, seems impossible because the entire universe is a closed physical system. What about the appeal to the random uncertainty of quantum mechanics, a popular if superficial free-will escape clause. That doesn’t seem to help—even if meaningful quantum computations could occur macroscopically in the hot, wet brain. After all, how could random uncertainty generate free will?
Is there no solution? After analyzing the arguments, van Inwagen, a savvy and sophisticated and not shy philosopher, concludes, “I regard free will as a complete mystery.”
For just this reason, the problem of free will takes us closer to truth.

Robert Lawrence Kuhn speaks with Peter van Inwagen, John Searle, Daniel Dennett, Susan Blackmore, Christof Koch, and Alan Leshner in “What Is Free Will?” the 23rd episode in the Closer to Truth: Cosmos, Consciousness, God TV series, which airs Thursdays on the PBS HD network and many other PBS stations. Every Friday, participants in the series will share their views on the previous day's episode.