An overview of free will and determinism (or, I may or may not be choosing to write this)

Jerry Coyne and Sam Harris have been pretty busy on the subject of free will lately, and I've engaged in some discussions across the interwebs with various people who share their perspective. It's one of the oldest debates in philosophy, but interest in the topic doesn't seem to be going anywhere. What's new, though, is the idea that science can actually prove we don't have free will. I think that's wrong, but I'll save it for another time.

I'm what's known as a "compatibilist". If there are two common ideas of free will, they are:
  • Dualism and libertarian free will
  • Naturalism and determinism
There's a common, and in my opinion misguided, assumption that the only way we can talk about free will is if the mind is somehow disembodied from the brain, and able to circumvent those pesky laws of physics. That kind of argument has never made sense to me, even from a theistic standpoint – after all, why would God go about making this incomprehensibly complex universe governed by all these laws, and then decide that a perpetual miracle of sorts would be required for even the most basic human behavior (and perhaps that of some other higher animals)?

Compatibilism is basically this
  • Determinism and a certain kind of free will
I prefer to talk about free will and determinism in their simplest terms, to avoid all that "Well, what do you actually mean by free will?" crap. I take free will simply to mean the ability to choose, to have volition. There are some definitions of free will that have to be done away with; namely the aforementioned "libertarian" or "contra-causal" free will. We don't get a pass on the laws of physics. We don't get to make decisions free of a litany of internal and external influences. Our environment, our social interactions, and the very makeup of our brains all profoundly influence our behavior. The playing field is simply not level, and I don't think any reasonable person would dispute this fact.

Determinism can be an equally fuzzy concept, but I'm going to take traditional approach: it's the idea that if we understood all the positions of all the particles in the universe, and we could plug this information into some kind of mathematical formula, we could always predict human behavior. Determinism says choice is fundamentally an illusion. We're automatons, not really making choices but simply the products of inevitability. This is summed up poetically by what's called "Laplace's demon", from the philosopher Pierre-Simon Laplace:
We may regard the present state of the universe as the effect of its past and the cause of its future. An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.

Compatibilism throws a hook into the discussion; it says we can live in a deterministic universe and still have free will – at least in the ways that really matter. To that end, "determinism" as described above (the "we are automatons" idea) is really more accurately described as "hard determinism". That's the position that folks like Sam Harris and Jerry Coyne take.



Hurdles of (hard) determinism

Determinism raises some rather big issues. If we're not really "free" to make any decisions, then moral responsibility is also illusory. The entire idea of "ought" is irrelevant. To quote Massimo Pigliucci in response to Jerry Coyne,
How is it possible to argue that we “should” do X in order to achieve Y if, as Jerry’s intellectual kin, Alex Rosenberg, would put it, “the physical facts fix all the facts”? It is hard for me to make sense of a position that denies that we have any choice in any matter, while at the same time advocating that we should or should not do certain things rather than others. How can we have a choice to contemplate (or not) what Jerry is proposing? How can we then decide to build a kinder world? And since morality itself is an illusion, why should we try to build a kinder world anyway?
I think Massimo hits the nail on the head. This reveals one of the biggest problems with hard determinism: it's philosophically masturbatory. Even if it turns out to be true, it is absolutely without application to our actual lives. We still have to live as though we have volition, and we still have to hold others accountable for their behavior. Even Sam Harris, in his new book, stumbles over this problem. From his old blog entry (which now redirects to his ebook on free will... titled, creatively, "Free Will"):
The great worry is that any honest discussion of the underlying causes of human behavior seems to erode the notion of moral responsibility. If we view people as neuronal weather patterns, how can we coherently speak about morality?
Sam further identifies "the intention to do harm" (emphasis his) as that for which we are justified in holding others responsible. But according to Sam's hard determinism, our intentions are not our own any more than our behavior; thus the hurdle of reconciling the idea of viewing humans as "neuronal weather patterns" with the idea that we have to be responsible for our choices hasn't been overcome. It just can't work in real life.


The problem with reductionism

I suppose I'm not persuaded by hard determinism because the entire position is based on a sort of extreme reductionism. Neurons are not free; our brains are composed of neurons, thus our brains are not free. But this is just a fallacy of composition – it's possible that brains exhibit emergent properties not present in its constituent parts. If we take the reductionist approach, we can just keep going down to quarks (or strings, perhaps) and ever more impossibly complex calculations. In the words of Caltech physicist Sean Carroll, "classical mechanics isn’t right; it’s just an approximation to quantum mechanics". So we can keep chopping away, and at some point we'll have quantum indeterminacy. That doesn't give us libertarian free will, but it dispenses with the idea that the universe is like an unwinding clock, and we're all subject to a singular inevitable fate no matter what we think we are choosing.

The dichotomy between quantum mechanics and classical physics in many ways parallels the dilemma of free will; to say that free will does not exist is to say that some fundamental description of reality is incompatible with the idea of free will; as Sam Harris says, it's a "non-starter, philosophically and scientifically". But equations that are useful for describing the behavior of particles are not very useful for describing the behavior of baseballs – just as the laws of chemistry, though at a fundamental level of all biology, are not very useful in explaining evolution. 

In his book The Grand Design, Stephen Hawking posits what he calls "model-dependent realism". This is the idea that we don't have any ultimate, indisputable description of reality by which to measure the accuracy of various theoretical descriptions of it. Instead, what we say is "real" really comes down what model of reality best fits the data. From the book:
There is no picture- or theory-independent concept of reality. Instead we will adopt a view that we will call model-dependent realism: the idea that a physical theory or world picture is a model (generally of a mathematical nature) and a set of rules that connect the elements of the model to observations. This provides a framework with which to interpret modern science.
We have to look at free will, and volition, a bit differently then. Sean Carroll has a fantastic analogy with the concept of "time":
The microscopic laws of physics (as far as we know) are perfectly reversible; evolution forward in time is no different from evolution backward in time. But the macroscopic world is manifestly characterized by irreversibility. That doesn’t mean that the two descriptions are incompatible, just that we have to be careful about how they fit together. In the case of irreversibility, we realize that we need an extra ingredient: the particular configuration of our universe, not just the laws of physics.
He continues,
If we know the exact quantum state of all of our atoms and forces, in principle Laplace’s Demon can predict our future. But we don’t know that, and we never will, and therefore who cares? What we are trying to do is to construct an effective understanding of human beings, not of electrons and nuclei. Given our lack of complete microscopic information, the question we should be asking is, “does the best theory of human beings include an element of free choice?” The reason why it might is precisely because we have different epistemic access to the past and the future. The low entropy of the past allows for the existence of “records” and “memories,” and consequently forces us to model the past as “settled.” We have no such restriction toward the future, which is why we model the future as something we can influence. From this perspective, free will is no more ruled out by the consequence argument than the Second Law of Thermodynamics is ruled out by microscopic reversibility.

What Sean Carroll is arguing – which is really the same sort of thing Dan Dennett is arguing in his many musings on free will, including his book Freedom Evolves – is that any useful model of human behavior requires us to view humans as rational agents capable of making choices, just as "time" is a necessary component of any useful model of reality, even if at some "fundamental" level it is not "real". 

This means that it's actually Sam Harris' own position that is the philosophical and scientific non-starter. It's wholly dependent on counterfactual claims (e.g., 'I could not have chosen differently') that are unfalsifiable, and it requires access to information that is impossible to attain. Just as we could argue that free will is an illusion, we could also argue that time is an illusion, that evolution is an illusion, that consciousness and self-awareness are illusions, that the laws of thermodynamics are illusions (since they're all ultimately reducible to quantum states). But none of these are useful models of reality. To again pull from Stephen Hawking,
According to model-dependent realism, it is pointless to ask whether a model is real, only whether it agrees with observation. If there are two models that both agree with observation ... then one cannot say that one is more real than another. One can use whichever model is more convenient in the situation under consideration
There are no grounds, then, to say that free will is any less "real" than time, the laws of thermodynamics, evolution, or consciousness. They are all emergent properties of the universe, and any model of our reality must include them. This is what compatibilism entails – it doesn't matter whether the universe is deterministic at some fundamental level. The emergent property we call free will – or, as I prefer to say, volition – is a necessary component of any useful model of human behavior.



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