Undetermined - a response to Robert Sapolsky. Part 1 - a tale of two neuroscientists

Free will is in the air. Among neuroscientists at least, the question of whether we are in control of our actions has been attracting renewed attention of late, driven in large part by the successes of the field in laying bare the neural machinery of behaviour. It’s thus not a total coincidence that two books by neuroscientists on this topic – Determined, by Robert Sapolsky, and Free Agents, by yours truly – have been published so close together (both in October, 2023). What may be more surprising to readers is that we reach such divergent conclusions on the topic.

With thanks to Bill Sullivan

That we can survey the same evidence and interpret it so differently may suggest to some that the question of free will is not really an empirical one at all. Of course many of the issues are metaphysical, but both Prof. Sapolsky (Sapolsky hereafter) and myself think that the science of decision-making is at least relevant to these philosophical discussions. In short, he thinks that science definitively rules out the possibility of free will. I think it doesn’t. In fact, I think we can construct a perfectly unproblematic scientific framework that naturalises the concept.


A number of reviews have compared our two books (including The Times Literary Supplement, Nature, The Wall Street Journal, Undark magazine, 3 Quarks Daily, Nautilus, and others), and we also had the chance recently to debate the issue. But there were many points left unexplored and here I want to respond more directly and more thoroughly to some of the claims that Sapolsky makes in his book. 



Where we agree


First, I should point out numerous areas where Sapolsky and I agree. A prominent view on free will among philosophers and those scientists who trouble themselves with the issue is compatibilism. This is the view that determinism holds (more on what this is taken to mean below), but that free will can be taken to be compatible with it. Or more precisely, that the concept of moral responsibility can be taken to be compatible with determinism. As espoused most forcefully by people like philosopher Daniel Dennett, this view accepts that there is only one possible future, but still argues that agents can be held responsible for their actions if they are acting for their reasons, even if they actually never have any choice in what occurs. Both Sapolsky and I find this view incoherent.


I also think it’s moot, given the evidence from physics that the universe is not in fact deterministic in that fashion. Sapolsky appears to agree with this and accepts that there is fundamental indeterminacy at the lowest levels. What he takes this to mean for determinacy at higher levels is a little less clear and is something I will come back to. 


We also agree that there are all kinds of factors that influence our behaviour. My previous book, Innate, was all about how the wiring of our brains shapes who we are. We are definitively not born as blank slates, but have our own individual natures – innate predispositions that derive from our genetics and the way our brain happened to develop. Both Sapolsky and I agree that these predispositions affect the way our patterns of behavior emerge throughout our lives.


However, I take these effects to be distal, indirect, and non-exhaustive, which is why I used the word “shapes” rather than “determines”. As we will see below, one of the main points of disagreement is that I think of these and other factors as influences on our behaviour while Sapolsky sees them as absolute determinants of it.


Finally, I am very sympathetic with Sapolsky’s concern for what philosophers call “moral luck”. This is the idea that many of the things that people do in life – many of the ways in which their lives turn out – are due to factors over which they had no control and for which they deserve neither credit nor blame. This includes their natural endowments – talents, cognitive capacities, personality traits, and so on – as well as their social circumstances. Where we differ on this point is that I think it is perfectly possible to take such factors into account in moral or legal considerations, without having to take an absolutist metaphysical position that these prior causes preclude any capacity of decision-making whatsoever on the part of the individual. 


Clearly, then, we see much of the evidence regarding the nature of the world and the nature of human beings as entities the same way. Nevertheless, we end up with different conclusions. One explanation for this could be that we start with different premises, perhaps implicit or tacit ones. It is thus worth exploring the assumptions and stances we bring to bear that inform our thinking.



Closet dualism


Sapolsky rightly criticises the position of dualism – the idea, inherited from Descartes, that there are two separate kinds of stuff, physical and mental. Under this view, the mental realm is where we make decisions, thus freeing us from the confines of physical determinism. This implies the existence of a “ghost in the machine” – an immaterial self that somehow inhabits your brain and body and pushes things around. Sapolsky derides this view as unscientific, which it obviously is, and rightly says that it provides no solution to the problem of free will – at least none that any scientist committed to the idea of physicalism (basically, no magic allowed) should accept.


However, his own position is dualist through and through. Right from the get-go, he frames the idea that a human being – as a whole entity – could be a cause of something as ludicrous and supernatural. On page 2, he writes, in relation to any behavior, that we can ask:


Why did that behavior occur? If you believe that turtles can float in the air, the answer is that it just happened, that there was no cause besides that person having simply de­cided to create that behavior. Science has recently provided a much more accurate answer, and when I say “recently,” I mean in the last few centu­ries. The answer is that the behavior happened because something that preceded it caused it to happen.


I guess I’d better explain the reference to turtles! This refers to an anecdote about a woman arguing with William James that he had his cosmology all wrong and the earth really rested on the back of a turtle. When he asked her what the turtle rested on, she said “another turtle”. And when he asked the inevitable question of what that turtle rested on, she replied: “It’s no use, Professor James. It’s turtles all the way down!” I gather Sapolsky is sympathising with the woman in the story, in the sense that every cause that we might give for an action inevitably has the same kind of regress of prior causes that it “rests on”. (There is also a hint here of the reductionist instincts that permeate the book – looking down instead of up).


The framing of the issues in the cited paragraph is firmly, though implicitly, dualist. First, there is the odd idea that a behavior occurring because the person “simply” decided to do something is basically identical to it having “just happened”, as if for no reason. But the whole point is that we can do things for our reasons, not at random. And as we will see, there is nothing “simple” about our decision-making processes. Nor is there any reason, a priori, to rule out the possibility of the person themselves being a cause of things – that’s the very question under debate.


Then there’s the implication that any such causation would require a miracle (the floating turtle) and is thus patently absurd. This only follows from the dualist position that when we say something is up to you, the “you” must be some kind of immaterial soul or ghost in the machine – as opposed to just your holistic self. Again, this rules out from the get-go a more naturalistic explanation – the very thing we’re after.


And finally, there is the assertion that science can replace – and indeed has replaced – such superstitious absurdities with the real explanation, which is couched in a linear chain of inexorable and inevitable causes of the respectable sciencey kind.


These themes are repeated throughout the book. On multiple occasions, Sapolsky implies that if biological factors are at work, these can’t provide the explanation or the vehicle for any real kind of free will, just by definition.


Each prior influence flows without a break from the effects of the influences before. As such, there’s no point in the sequence where you can insert a freedom of will that will be in that biological world but not of it. (Page 46)


The image of “inserting” a freedom of the will into the biological world, so that it is “in it, but not of it” is a clear articulation of a dualist position.


Again, on page 83:


In order to prove there’s free will, you have to show that some behavior just happened out of thin air in the sense of considering all these biologi­cal precursors.


Why “out of thin air”, as if this requires magic? This just assumes that the individual cannot be a cause of their own behavior – exactly the question at hand. If you set up the problem such that the only solution that would meet the threshold of free will is one involving this kind of supernatural interference in the normal run of physical causation, then of course you will never be satisfied by any naturalistic claim that explicates behavioural control as an evolved capacity of living organisms.



God of the gaps


This dualistic framing is also evident in Sapolsky’s repeated assertion that the only place where “you” can reside is in the gaps in our current knowledge of biology. Science is seen as revealing the real causes of what happens, at deeper and deeper mechanistic levels. As this occurs, there seems less and less for you to do, less and less room for any kind of holistic or top-down causation. All the causal power is located at the lowest levels (whatever they are taken to be) and the notion of higher-order causation by the self, as a whole entity, is eliminated in the process.


This is, of course, how atheist scholars characterise religion, as having to stage strategic retreats with every advance of science, taking refuge in whatever mysteries remain – hence, the god of the gaps. The implication is that science will eventually close all these gaps and the need to invoke a deity to explain anything at all will disappear.


Sapolsky’s eliminative reductionism similarly seeks a full causal explanation of behavior in the biological mechanisms that science is laying bare. This is thus the flip side of his implicit dualism – if the only thing that would be real free will is control by an immaterial self, apparently without involving any mechanism, then of course the more mechanisms biology reveals, the less room there is for the self to wield any influence, or even to exist at all.


My own position is one of non-reductive materialism. We don’t need to invoke any supernatural forces to explain how organisms can control their actions and how agents can have causal power in the world. There are plenty of resources available to us in the various sciences of systems that give perfectly naturalised concepts of holistic or top-down causation. Sapolsky considers some of these ideas in later chapters, but in a disappointingly dismissive way that, in my view, fails to fully engage with them. As such, I think he misses the very ideas we need to understand how causal agency can exist. It may be turtles all the way down, but it’s not turtles all the way up.



“Don’t look up!”


In eliminating the possibility of the whole self being a causal entity, Sapolsky offers a different challenge to proponents of free will, one that looks down, instead of up. In the first chapter, for example, he describes a scenario where a man pulls the trigger of a gun. He describes the set of causes of this event as the series of nerve impulses, working backwards from the ones that caused his trigger finger to contract, to the ones that caused those neurons to fire, and so on. (Note the purely mechanistic, driving framing – more on that later). He then says:  


Here’s the challenge to a free willer: Find me the neuron that started this process in this man’s brain, the neuron that had an action potential for no reason, where no neuron spoke to it just before. (page 14)


The idea is that if you could show him “a neuron being a causeless cause in this sense”, then you would have proven free will. This just strikes me as such an odd set-up. Why would some neuron firing at random and thereby causing a behavior constitute an instance of free will? Why look for such a reductive explanation, at the level of specific neurons? We know that’s not how the brain works. He goes on to say:


The prominent compatibilist philosopher Alfred Mele of Florida State University emphatically feels that requiring something like that of free will is setting the bar “absurdly high.” (page 15)


I disagree. It’s not that the bar is too high. It’s just the wrong bar. We’re on the wrong playground. What he’s asking for would not in fact satisfy anyone’s concept of free will, including his own (because it would not give any causal power to the individual). He’s looking down when he should be looking up (but not up so far that the explanation has to sit somehow outside our heads in a ghostly self).


So, we differ in some of our philosophical stances in ways that provide at least some explanation for why our interpretation of the scientific evidence also differs so profoundly.


As to that evidence itself, most reviewers have taken Sapolsky’s presentation of it as a fair assessment of the profound influence that a whole range of biological factors can have on our behavior. Here, I am in an odd position: I agree that such factors can influence our behavior – of course they can – but I find the actual evidence that Sapolsky marshals to support this notion to be highly flawed. Indeed, the types of studies that he leans on to make this argument are literally ones that I (and many others) use as prime examples in lectures about irreproducible science and the “replication crisis”.


More on that in Part 2.


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