UPDATE: Reader Chris Quartly noticed that I posted about this same article by Al-Khalili in January here. All I can say is that I forgot; blame it on advancing age. At any rate, those readers who didn’t catch the earlier post may want to engage with this one. Mea culpa. Too, my views have developed since then, and there have been additional neuroscience experiments showing that decisions are partly predictable up to several seconds before the subject is aware of having made them.
Most of you have probably heard of Jim Al-Khalili, who has a busy career as a professor of physics at the University of Surrey, as a broadcaster on the BBC (he does “The Life Scientific” show, and I believe he once interviewed me about Steve Jones), and as president of the British Humanist Association. He also has his own eponymous website.
Al-Khalili is clearly one of the good guys, but I think he erred a bit when he put up a post on January 18 that just came to my attention: “Do we have free will—a physicist’s perspective?” The answer, of course, is “yes.” (How often do you see anyone say “no” these days?”) But his reasons for thinking that we have free will are odd, and ones that I haven’t yet encountered.
Al-Khalili seems to be a compatibilist—that is, he seems to find physical determinism compatible with free will, though he sees quantum mechanics as throwing a wrench into the determinism. I agree: if we reran the tape of the universe, or even the tape of life, I think things would come out differently, for in the origins of the universe, and probably in the origins of new species, true quantum indeterminism plays a role. In the case of life, for instance, it may have a hand in the production of mutations, which are the very fuel of evolution.
But Al-Khalili, unlike some other compatibilists, doesn’t see quantum indeterminacy as rescuing free will. And I don’t think others, do, either—even if that indeterminacy plays out in our brains so that at any given moment we could equally well make either of two decisions. That kind of “quantum” free will is based on pure physical randomness and, to paraphrase Dan Dennett, “is not the kind of free will worth wanting.”
No, Al-Khalili finds free will elsewhere: in unpredictability. That is, our brains are incredibly intricate—they contain roughly ten billion nerve cells, each cell connected to others through about 10,000 synapses (cell-to-cell connections made via chemical or electrical stimuli)—so predicting how a series of environmental inputs will result in a given behavioral output—a decision—can often be impossible. We do know that certain behaviors are broadly predictable: how often have you said, when a friend made a decision, “I knew she would act that way!—but predicting fine-scale behaviors like dinner choices and the like may be forever beyond our abilities, even when we learn a lot more about the brain. The input-output algorithm is just too complicated.
Nevertheless, it may be possible to predict which decision a person can make not from first principles of understanding one’s wiring, but simply by scanning the brain in advance. Recent neuroscience studies, many highlighted on this site, show that one can predict with fair accuracy the results of a dichotomous choice (which button to press, whether to add or subtract two numbers) several seconds before the subject is conscious of having made it. So Al-Khalili may be asking too much to predict decisions from brain wiring. That may be superfluous given that we may ultimately be able to predict them with fair accuracy from brain activity itself, and I’m pretty sure we’ll be able to do this for many behaviors when our scanning methods improve.
Too, many decisions can’t be predicted way in advance, simply because we don’t know what environmental inputs bear on a decision until close to the time it’s made. You may, for instance, decide to order lamb chops at a restaurant because your brain receives the environmental input of seeing an adjacent diner tucking into a rack of lamb only a few seconds before you order.
All this aside, though, for I think Al-Khalili goes wrong when he says that our decisions are free because we don’t know enough about the brain to predict them. In his words (note that he explicitly rejects quantum mechanics as a basis for free will):
So do we have free will or don’t we? The answer, despite what I have said about determinism, is yes I believe we still do. And it is rescued not by quantum mechanics, as some physicists argue, but by chaos theory. For it doesn’t matter that we live in a deterministic universe in which the future is, in principle, fixed. That future is only knowable if we were able to view the whole of space and time from the outside. But for us, and our consciousnesses, imbedded within space-time, that future is never knowable to us. It is that very unpredictability that gives us an open future. The choices we make are, to us, real choices, and because of the butterfly effect, tiny changes brought about by our different decisions can lead to very different outcomes, and hence different futures.
So, thanks to chaos theory our future is never knowable to us. You might prefer to say that the future is preordained and that our free will is just an illusion, but the point is our actions still determine which of the infinite number of possible futures is the one that gets played out. . . It is precisely this unavoidable unpredictability about how a complex system such as our brain works, with all the thought processes, memories, interconnected networks with their loops and feedbacks, that gives us our free will.
Chaos theory, of course, is deterministic: it’s a theory that simply says that very slight alterations in the initial conditions of a complex system (say, weather patterns) can lead to very different outcomes (whether you get a hurricane). It’s all deterministic, playing out through the non-quantum laws of physics. It’s just that, like the three-body problem, we don’t know enough to work out such systems from first principles.
What baffles me is how you can derive “free will”, if that term has any meaning, from unpredictability. Yes, we can’t predict our decisions, but they still are, according to Al-Khalili, determined by the laws of physics. How does that add up to “freedom” in any meaningful sense? His statement that the choices are “real” choices is ambiguous. They look as if they are choices, but in principle we could have predicted them had we sufficient knowledge. They are illusory choices—choices that aren’t what they seem to be or how they feel to us as agents. There is still only one future; it’s just that we can’t predict it. And if those futures are altered by tiny differences in the environment, or previous “decisions” (i.e., brain states), well, that’s still deterministic and predictable in principle.
In the end, Al-Khalili says that, predictable or not, it doesn’t really matter whether our decisions are pre-determined:
Whether we call it true freedom or just an illusion in a way does not matter. I can never predict what you might do or say next if you really want to trick me because I cannot in practice ever model every neuronal activity in your brain, anticipate every changing synaptic connection and replicate every one of those trillions of butterflies that constitute your conscious mind in order for me to compute your thoughts. That is what gives you free will. This despite the actions of the brain most probably remaining fully deterministic – unless quantum mechanics has a bigger say in the matter than we currently understand.
But he’s wrong here. It is critical whether our free will is an illusion or not. It matters whether our decisions simply reflect the laws of physics acting on our brain. Why? For two reasons. First, because it dispels the widespread and religiously based view that we can make true contracausal choices, and that those choices influence our postmortem fate. What kind of God would send you to heaven or hell simply because your brain obeys the laws of physics? That means that you really don’t have a choice of accepting Jesus as your personal savior: that choice is purely the result of your genes and environment. Of course, as an atheist, Al-Khalili would certainly concur.
But the more important reason why the illusory nature of free will matters is because it has profound implications for how society metes out punishments and rewards. If a criminal has no choice about his actions, then we should treat him differently, something we already do when we take into account “mental capacity” when sentencing criminals. Well, all of us have “diminished capacity” because our choices are completely constrained by our genes and environment. And if that’s the case, then we should punish not for retribution (even though we do), but for three reasons: rehabilitation, to set an example for others, and to keep dangerous people out of society. And the efficacy of those punishments can, in principle, be determined scientifically. The efficacy of retribution cannot.
In other words, recognizing that free will is not “true freedom” (which Al-Khalili really admits it isn’t!) but illusory can help us build a better society, one in which we treat others in a way that’s best for them and society as a whole. We may, for example, determine that, compared to incarceration without parole, the death penalty achieves nothing and, in fact, could make society more brutal. The death penalty accomplishes nothing beyond retribution, since it’s actually more expensive than lifelong imprisonment.
All that aside—and I’m sure some readers will disagree—I find it odd that Al-Khalili buttresses his free will with the struts of unpredictability. That’s a tactic I haven’t seen used by compatibilists, but of course I haven’t read everything about free will.
Nevertheless, the logical extension of Khalili’s views is that many other animals, and even some plants, have free will as well. After all, can we predict from first principles how an earthworm will move, or how many leaves a tree will produce? Those, too, are subject to chaos theory.