Confusion about free will, reductionism and emergence

Psychology Today has just published: “Finding the Freedom in Free Will, with the subtitle: “New theoretical work suggests that human agency and physics are compatible”. The author is Bobby Azarian, a science writer with a PhD in neuroscience. The piece is not so much wrong — I actually agree with the main conclusions — but is, perhaps, rather confused. Too often discussion in this area is bedevilled by people meaning different things by the same terms. Here is my attempt to clarify the concepts. Azarian starts:

Some famous (and brilliant) physicists, particularly those clearly in the reductionist camp, have gone out of their way to ensure that the public believes there is no place for free will in a scientific worldview.

He names Sabine Hossenfelder and Brian Greene. The “free will” that such physicists deny is “dualistic soul” free will, the idea that a decision is made by something other than the computational playing out of the material processes in the brain. And they are right, there is no place for that sort of “free will” in a scientific worldview.

Azarian then says:

Other famous scientists—physicists, neuroscientists, and complexity scientists among them—have a position virtually opposite of Greene’s and Hossenfelder’s …

He names, among others, David Deutsch and the philosopher Dan Dennett. But the conception of “free will” that they espouse is indeed just the computational playing out of the material brain. Such brain activity generates a desire to do something (a “will”) and one can reasonably talk about a person’s “freedom” to act on their will. Philosophers call this a “compatibilist” account of free will.

Importantly, and contrary to Azarian’s statement, this position is not the opposite to Greene’s and Hossenfelder’s. They are not disagreeing on what the brain is doing nor about how the brain’s “choices” are arrived at. Rather, the main difference is in whether they describe such processes with the label “free will”, and that is largely an issue of semantics.

All the above named agree that a decision is arrived by the material processes in the brain, resulting from the prior state of the system. Any discussion of “free will” needs to distinguish between the dualistic, physics-violating conception of free will and the physics-compliant, compatibilist conception of free will. They are very different, and conflating them is just confused.

Do anti-agency reductionists believe that the theories of these scientists are not worth serious consideration?

No, they don’t! What they do think is that, when talking to a public who might interpret the term “free will” in terms of a dualistic soul operating independently of material causes, that it might be better to avoid the term “free will”. People can reasonably disagree on that, but, again, this issue of semantics is distinct from whether they agree on what the brain is doing.

Origins-of-life researcher Sara Walker, who is also a physicist, explains why mainstream physicists in the reductionist camp often take what most people would consider a nonsensical position: “It is often argued the idea of information with causal power is in conflict with our current understanding of physical reality, which is described in terms of fixed laws of motions and initial conditions.”

Is that often argued? Who? Where? This is more confusion, this time about “reductionism”. The only form of “reductionism” that reductionists actually hold to can be summed up as follows:

Imagine a Star-Trek-style transporter device that knows only about low-level entities, atoms and molecules, and about how they are arranged relative to their neighbouring atoms. This device knows nothing at all about high-level concepts such as “thoughts” and “intentions”.

If such a device made a complete and accurate replica of an animal — with every molecular-level and cellular-level aspect being identical — would the replica then manifest the same behaviour? And in manifesting the same behaviour, would it manifest the same high-level “thoughts” and “intentions”? [At least for a short-time; this qualification being necessary because, owing to deterministic chaos, two such systems could then diverge in behaviour.]

If you reply “yes” then you’re a reductionist. [Whereas someone who believed that human decisions are made by a dualistic soul would likely answer “no”.]

Note that the pattern, the arrangement of the low-level entities is absolutely crucial to this thought experiment and is central to how a reductionist thinks. A Star Trek transporter does not just deliver the atoms and molecules in a disordered heap, and then expect the heap to jump up and fight Klingons.

The caricature of a reductionist is someone who would see no difference between a living human brain and a human brain put through a food blender. It shouldn’t need saying that such a view is so obviously wrong that no-one thinks like that.

What is the difference between a tree and an elephant? It is not the component parts. Trees and elephants are made of the same atoms (carbon, oxygen, nitrogen and hydrogen make up 96% of an organism’s weight, with the rest being a few other types of atoms). After all, elephants are made up of what they eat, which is trees. Indeed, by carefully controlling the water supply to a tree, one could, in principle, make its constituent atoms identical to those of a same-weight elephant.

So the difference between a tree and an elephant — and the cause of their different behaviour — is solely in the medium-scale and large-scale arrangement of the component parts. No reductionist (other than those constructed out of straw) disagrees.

Azarian then spends time contrasting a fully deterministic view of physics with the possibility of quantum-mechanical indeterminacy. This is more confusion. That topic is irrelevant here. Whether the state of the system at time t+1 is entirely specified by the state at time t, or whether there is also quantum dice throwing, is utterly irrelevant to concepts of “will”, “intention”, “agency” and “freedom” because quantum dice throwing doesn’t give you any of those.

Indeed, Azarian accepts this, saying: “quantum indeterminism alone does not help the notion of free will much since a reality with some randomness is not the same as one where an agent has control over that randomness”. But he then argues (quoting George Ellis) that: “While indeterminacy does not provide a mechanism for free will, it provides the “wiggle room” not afforded by Laplace’s model of reality; the necessary “causal slack” in the chain of cause-and-effect that could allow room for agency, …”.

I agree that we can sensibly talk about “agency”, and indeed we need that concept, but I don’t see any way in which quantum indeterminacy helps, not even in providing “wiggle room”. [And note that, after invoking this idea, Azarian does not then use it in what follows.]

If we want to talk about agency — which we do — let’s talk about the agency of a fully deterministic system, such as that of a chess-playing computer program that can easily outplay any human.

What else “chooses” the move if not the computer program? Yes, we can go on to explain how the computer and its program came to be, just as we can explain how an elephant came to be, but if we want to ascribe agency and “will” to an elephant (and, yes, we indeed do), then we can just as well ascribe the “choice” of move to the “intelligent agent” that is the chess-playing computer program. What else do you think an elephant’s brain is doing, if not something akin to the chess-playing computer, that is, assessing input information and computing a choice?

But, Azarian asserts:

The combination of the probabilistic nature of reality and the mechanism known as top-down causation explains how living systems can affect physical reality through intentional action.

Top-down causation is another phrase that means different things to different people. As I see it, “top-down causation” is the assertion that the above Star-Trek-style replication of an animal would not work. I’ve never seen an explanation of why it wouldn’t work, or what would happen instead, but surely “top-down causation” has to mean more than “the pattern, the arrangement of components is important in how the system behaves”, because of course it is!

Top-down causation is the opposite of bottom-up causation, and it refers to the ability of a high-level controller (like an organism or a brain) to influence the trajectories of its low-level components (the molecules that make up the organism).

Yes, the high-level pattern does indeed affect how the low-level components move. An elephant’s desire for leaves affects where the molecules in its trunk are. But equally, the low-level components and their arrangement give rise to the high-level behaviour. So this is just another way of looking at the system, an equally valid way of looking at the system that is. But it is not “the opposite of bottom-up causation”. Both views have to be fully valid at the same time. Unless you’re asserting that the Star-Trek-style replication would not work. And if you’re doing that, why wouldn’t it?

This means that biological agents are not slaves to the laws of physics and fundamental forces the way non-living systems are.

Well, no, this is wrong in two ways. First, the view that the low-level description gives rise to the high-level behaviour is still equally valid and correct, so the biological agents are still “slaves to the laws of physics and fundamental forces”. That is, unless you’re advocating something way more novel and weird than you’ve said so far. And, second, this would apply just as much to non-living systems that have purpose such as the chess-playing computer.

One might reply, but that “purpose” only arises as a product of the Darwinian evolution of life, and I may readily agree with that, but that’s a somewhat different distinction.

With the transition to life, macroscopic physical systems became freed from the fixed trajectories that we see with the movement of inanimate systems, which are predictable from simple laws of motion.

If that is saying only that life evolved to be more complex than non-living things, and thus their behaviour is more complex (and can be sensibly described as “purposeful”), then yes, sure, agreed.

The emergence of top-down causation is an example of what philosophers call a “strong emergence” because there is a fundamental change in the kind of causality we see in the world.

Well, no. Provided you agree that the Star-Trek-style replication would work, then this counts as weak emergence. “Strong” emergence has to be something more than that, entailing the replication not working.

Again, words can mean different things to different people, but the whole point of “strong” emergence is that “reductionism” fails, and reductionism (the sort that anyone actually holds to, that is) is summed up by the Star-Trek-style replication thought experiment.

[I’m aware that philosophers might regard the view summed up by that thought experiment as being “supervenience physicalism”, and assert that “reductionism” entails something more, but that’s not what “reductionism” means to physicists.]

And if by “a fundamental change in the kind of causality we see in the world” one means that Darwinian evolution leads to hyper-complex entities to which we can usefully ascribe purpose, intention and agency, then ok, yes, that is indeed an important way of understanding the world.

But it is not really “a fundamental change in the kind of causality we see in the world” because the bottom-up view, the view that these are collections of atoms behaving in accordance with the laws of physics, remains fully valid at the same time!

I’m actually fully on board with viewing living creatures as entities that have intentions and which exhibit purpose, and fully agree that such high-level modes of analysis are, for many purposes, the best and only ways of understanding their behaviour.

But it is wrong to see this as a rejection of reductionism or of a bottom-up way of seeing things. Both perspectives are true simultaneously and are fully compatible. I agree with the view that Azarian is arriving at here, but regard his explanation of how it is arrived at as confused.

… agency emerges when the information encoded in the patterned interactions of molecules begins telling the molecules what to do.

True, but it always did. Even within physics, the pattern, the arrangement of matter determines how it behaves, and hence the arrangement will “tell molecules what to do”. Even in a system as simple as a hydrogen atom, the arrangement of having the electron spin aligned with the proton spin will lead to different behaviour from the arrangement where the spins are anti-aligned.

Towards the end of the piece, Azarian’s and my views are perhaps converging:

The bottom-up flow of causation is never disrupted — it is just harnessed and directed toward a goal. We still inhabit a cause-and-effect cosmos, but now the picture is more nuanced, with high-level causes being every bit as real as the low-level ones.

Agreed. Azarian then explains that, when it comes to biological systems, what matters for behaviour is the macrostate of the system (the high-level “pattern”) rather than the microstate (all the low-level details).

Yes, agreed. But that is also just as true in physics. Analysing a physical system in terms of its macrostate (where many different microstates could constitute the same macrostate), is exactly the mode of analysis of “statistical mechanics”, which is at the heart of modern physics.

Azarian quotes neurogeneticist Kevin Mitchell in (correctly) saying that:

The macroscopic state as a whole does depend on some particular microstate, of course, but there may be a set of such microstates that corresponds to the same macrostate …

But he goes slightly wrong in quoting neuroscientist Erik Hoel saying:

Recent research has argued exactly this by demonstrating the possibility of causal emergence: when a macroscale contains more information and does more causal work than its underlying microscale.

The macrostate cannot contain more information (and cannot “do more causal work”) than the underlying microstate, since one can reconstruct the macrostate from the microstate. Again, that is the point of the Star Trek thought experiment, and if that is wrong then we’ll need to overturn a lot of science. (Though no-one has ever given a coherent account of why it would be wrong, or of how things would work instead.)

So, where are we? I basically agree with the view that Azarian arrives at. So maybe we’re just disagreeing about what terms such as “reductionism”, “strong/weak emergence” and “top-down” causation actually mean. It wouldn’t be the first time! As I see it, though, this view is not a new and novel way of thinking, but is pretty much what the hidebound, reductionist physicists (like myself) have been advocating all along. None of us ever thought that a living human brain behaves the same as that same brain put through a food blender.