Aaronson on QM and Free Will

One thing that has frustrated me in the past is the fact that folks tend to think indeterministic means “just random”, where by random they mean some stochastic process (like a dice roll) where one can’t predict which outcome will be chosen from some probability distribution. Quantum indeterminism doesn’t work this way, but it’s a difficult subject and experts don’t agree on exactly how to characterize it. It seems clear one cannot simply use a “frequency" interpretation, the way you can with a classical stochastic system. There seems to be something more involved, something spontaneous which resists reduction, but I have a hard time being more precise about this.

Computation theorist Scott Aaronson (home page, blog) recently gave a presentation on free will (at an FQXi conference) which was very thought-provoking (see this Sciam piece with helpful links), and had an interesting take on this issue.

Causal Regularity is not Universal but Rare

The picture of our universe as a machine governed by deterministic laws is hard to shake. Physics has profoundly undermined this vision of course, but even before this was known, it is a bit surprising that philosophers and scientists were inspired by everyday macroscopic experience to form such a conception. Was Hume so talented at billiards that he experienced constant conjunction? I can’t come close! Certainly to build and maintain a machine which achieves any determined outcome with regularity takes a lot of human effort.

This last point was made by philosopher John Dupré in a 1995 paper called “A Solution to the Problem of the Freedom of the Will” (hat tip: tweet by Rani Lill Anjum). This paper has a number of thought-provoking insights: contrary to the title, it’s doesn’t put forth a full theory of free will, but argues that the way the world works makes human autonomy unsurprising. (Dupré, a philosopher of biology among other research interests, took part in an interesting debate regarding reduction and emergence on Philosophy TV here). Most assume the world is governed by global microphysical laws, such that autonomy would require an exception to these laws. Dupré argues that we actually have no reason to think the world is governed by such globally applicable laws. Using his terminology, the world is far from causally complete.

Balaguer on Free Will, Part Three

The last post discussed Mark Balaguer’s argument that that the question of libertarian freedom reduces to the question of indeterminism at the point of decision.  In this post, I’ll summarize his argument that the presence or absence of the indeterminism in question is an open scientific problem.

Balaguer on Free Will, Part Two

There are two steps in Mark Balaguer’s argument (contained in chapters 3 and 4 of his book, respectively).  In the first step, the subject of this post, he argues that the question of freedom reduces to a question of indeterminism in decision-making.  In the second step (to be discussed in the next post) he argues that the presence or absence of the relevant indeterminism is an open scientific problem.

Balaguer on Free Will, Part One

After reading and enjoying one of Mark Balaguer’s papers on free will I also ordered and read his book Free Will as an Open Scientific Problem.   Not only did I like his approach to the topic, but his opening arguments, discussed below, clarified for me the reasons for my own vague dissatisfaction with much of the contemporary literature on free will.

(Note:  In these posts I’ll present much of the discussion in my own words; Balaguer himself is very precise in defining his terms and setting forth the arguments.  So, I recommend the book for those interested, but also in the online domain take a look at this paper, "The Metaphysical Irrelevance of the Compatibilism Debate", which overlaps with the first two chapters of the book, as well as a discussion of the paper and then the book itself in several posts and comment sections at the “The Garden of Forking Paths” blog – here, here, here, and here.)

The Free Will of Fruit Flies

I liked this short essay in Nature by Martin Heisenberg on free will (HT). Heisenberg is a neurobiologist (and the son of Werner), and his perspective is shaped by the work he’s done on more primitive organisms – in the essay he talks about bacteria and also the fruit flies (the famous drosophilia) which have been the subject of his own work. In short, the combination of microscopic randomness (ultimately sourced from the quantum realm) and an adaptive self-directedness (primitive intentionality -- see also here) comprise freedom.

In the human case, the discussion is obscured by the focus on the will found via introspective self-consciousness and its relation to our actions. But introspection is an extreme latecomer in evolution. Heisenberg suggests we have a kind of real freedom, shared with many other organisms, irrespective of whether our introspective picture is accurate or flawed. He says: “I maintain that we need not be conscious of our decision-making to be free. What matters is that our actions are self-generated…Why should an action become free from one moment to the next simply because we reflect upon it?”

Conway and Kochen vs. Determinism

John Conway and Simon Kochen are out with a paper called "The Strong Free Will Theorem" (HT), updating and "strengthening" their earlier paper (discussed here). Recall that the theorem begins with axioms which, while idealized, flow from accepted aspects of quantum theory and relativity and then concludes that if humans are assumed to be free in setting up experiments, then particles have the same kind of freedom in selecting among experimental outcomes. The theorem also serves as another argument toward ruling out hidden-variable interpretations of QM.

This paper presents a "stronger" version of the theorem, by showing it still works if one of the axioms is loosened, but otherwise the thrust is unchanged. In keeping with the earlier paper, though, the authors add to the formal argument some provocative philosophical comments, which I enjoy. Here's how the paper concludes:

"Although...determinism may formally be shown to be consistent, there is no longer any evidence that supports it, in view of the fact that classical physics has been superceded by quantum mechanics, a non-deterministic theory. The import of the free will theorem is that it is not only current quantum theory, but the world itself that is non-deterministic, so that no future theory can return us to a clockwork universe."

Common Sense: Both Wrong and Right

When it comes to our “folk” intuitions about the conscious self and free will, they can be wrong on the surface but still correct on a deeper level. I was reading Peter’s post on Conscious Entities about a neuroscientific paper on decision-making and conscious awareness (see additional discussion here). Like Libet’s work, the authors of the study appear to show that brain activity indicative of decision making precedes the subject’s awareness of making the choice. This again suggests the folk intuition that free will takes place at the level of reflective conscious awareness is flawed.

I concur with most of the commenters who expressed the view that this outcome has little bearing on the question of determinism and freedom at the metaphysical level. The human brain/body system is very complex and our higher order introspective awareness is a fragile construct embedded in this much larger context. And a simplistic division of the mind into a conscious and unconscious doesn’t do justice to the gradations of awareness.

When it comes to free will, our most fundamental theory of the natural world is indeterministic --it makes me wonder why we are even still debating determinism. There is no principle of quantum physics that states that indeterminism magically vanishes at macroscopic scales (the fact that we don’t observe macroscopic superpositions is not evidence that the large-scale world is described by classical physics). We may not be free in the way we think, but I think we are correct in viewing the future as open and believing that the sequence of natural events in which we participate is undetermined.

But does this imply that events are “just random”? Free choice on the part of a participating system would look like randomness from a third-person perspective. For a formal argument that there is a linkage between microscopic and human freedom, see this old post on the “Free-Will Theorem”.

[Update 4 June 2008: I changed the title of the post to the one I meant to have in the first place, swapping the order of 'right' and 'wrong']

Foundational Intuitions

I was thinking about the role intuitions play in philosophy and I found a nice paper by Steven D. Hales called “The Problem of Intuition”, which was published a few years ago. It contains a discussion of the role of intuition in philosophy and then presents an argument that philosophy is unavoidably founded on rational intuitions which have no external justification. This need not be viewed as a bad thing if we accept that some propositions can be self-justifying: they are the intuitive axioms upon which further reasoning is grounded. I thought Hales’ analysis in the paper made sense.

It’s worrisome, of course, that many of us seem to bring conflicting intuitions to philosophical debates. Yet I think we can still hope that we can find a secure shared foundation of at least some intuitive axioms.

So, what are they? What are yours? Famous philosophers of the past tried hard to base grand philosophical systems on carefully considered intuitive first principles. That style of philosophy is rare today. The long history of scientific advances overturning common sense intuition about empirical facts has inspired some philosophers to extrapolate further and argue that many of the deep intuitions we all presuppose in our daily lives are actually wrong and the result of illusion.

Two bedrock intuitions I view as axiomatic have been called into question by philosophers of a naturalistic bent. I maintain that there is no scientific finding or valid inference from the sciences that contravene these.

1. First-person experience is real. Because experiential facts accompany or precede all facts, experience cannot be completely grounded in non-experiential facts.

2. Possibilities are real. The future is open.

In considering these two I’m not saying that our common sense intuition about the nature of the conscious self and free will is accurate. Cognitive science and neuroscience will continue to reveal deep flaws in our “folk” conceptions of self and will. This is to be expected given that we are complicated composite organisms. But it is a mistake to infer from this that the axioms above are false.

Free Will: All the Way Down

I really enjoyed this paper: The Free Will Theorem, by Princeton Mathematics Dept. luminaries John H. Conway and Simon B. Kochen (HT: Clark’s sidebar, which linked to this Garden post, which linked in turn to this Times article).

Using axioms which implement an idealized EPR-style quantum spin measurement experiment (and assuming relativity), the authors set out to prove that:

If the choice of directions in which to perform spin 1 experiments is not a function of the information accessible to the experimenters, then the responses of the particles are equally not functions of the information accessible to them.

They call this the Free Will theorem since we in practice assume experimenters are free to set up the experiment the way they wish. So, the authors are not proving free will exists, they are proving that if free will exists at the human level, then the outcome exhibited by elementary particles will also be free.

The proof seems fairly straightforward once one accepts the earlier Kochen-Specker theorem (it can’t be said that the spin values for each direction already exist prior to measurement).

Following the presentation of the proof, the authors show (by discussing a way to modify Bohm’s theory) that QM is logically consistent if one assumes the assumption of particles expressing free will in a relativistic framework. Next, they relax some of the idealized assumptions to establish the robustness of the result in a more real world context.

The next section discusses how this result furthers the process (earlier marked by the K-S theorem and Bell's Theorem) of making hidden variable theories unworkable. They also argue it is an obstacle for GRW-type collapse models.

Further tidbits:

The authors argue that it is incorrect to interpret EPR-style experiments as meaning there is faster-than-light communication between particles; the particles are entangled as a collective system, but one will not confirm the predicted correlation until the future measurement of the other member of the pair. This is congruent with the perspective of Smerlak and Rovelli’s recent paper which interprets EPR from the perspective of relational quantum mechanics (RQM).

In terms of interpreting quantum mechanics: the authors argue quantum states (between measurements) are merely predictors (with probabilities) of what will happen if various measurements are performed. It is a mistake to ascribe concrete reality to the quantum states. This again is consistent with RQM’s perspective that it is the measurement events which are concretely real. The authors also state briefly that they don’t believe a conscious human mind is needed for collapse, but they don’t discuss in detail what they think is necessary. They think a future physics will explain what sort of “texture” surrounding a system will cause collapse.

The authors offer some philosophical remarks on free will. First, they remind the reader that they don’t claim to prove free will. They say “determinism, like solipsism, is logically possible.” They themselves do subscribe, however, to what a philosopher would call a naïve folk conception of libertarian free will. They don’t see how science could be taken seriously if its practitioners weren’t free to investigate nature by choosing what experiments to perform.

In any case, the linking of free will at the human level to free or spontaneous outcomes at the level of elementary quantum systems is an important result. It is also an especially appealing idea to a panexperientialist like me. While I appreciate the substantial problems which afflict the folk conception of free will, the results of this paper fit with my view that the conscious experience, intentionality, and (at least limited) free agency of human beings are all sourced from fundamental and ubiquitous properties of the natural world.

I also want to comment on a section toward the end entitled “Free versus Random?” It is extremely common to interpret QM as meaning the universe contains a fundamental indeterminism, but it is unusual to say it implies the existence of a fundamental freedom. Here’s a point the authors make in favor of the latter:

“Although we find ourselves unable to give an operational definition of either “free” or “random,” we have managed to distinguish between them in our context, because free behavior can be twinned, while random behavior cannot (a remark that might also interest some philosophers of free will).”

“Twinned” here refers to the entanglement of two particles. The measurement of the first of the twinned pair enables us to predict the outcome of the measurement of the second, so they aren’t individually random events. But I’m not sure this is a good argument: are we conflating the idea of a particle’s randomness with its independence? I’ll have to give this more thought.

I’m very interested in arguments which support my contention that the worldview implied by QM is richer and much more interesting than just classical physics plus an overlay of randomness. It isn’t just that the measurement outcome is random vs. determined. The quantum measurement event has intrinsically more to it than a classical billiard-ball notion of a causal event. It is an interaction between two systems where one system’s propensity toward an outcome is actualized by the second (measuring) system. I believe this actualization event or process carries with it the raw material of agency (as well as experience).

My Free Will Problem

I recently read Daniel Dennett’s book Freedom Evolves. In it, Dennett argues from his perspective of scientific naturalism that determinism is true. A large part of the book also offers a well-reasoned “compatibilist” argument that we shouldn’t think this conclusion compromises the effective existence of moral responsibility in our human social/cultural domain. I am comfortable with compatibilism, at least in the sense that I think human morality and responsibility can have a natural basis which doesn’t require believing we have some sort of absolute freedom. But I want to explore the argument for determinism itself here.

Here is a short caricature of Dennett’s argument for determinism:
1. Assume micro-physics doesn’t matter. Assume the fundamental units comprising humans and their environment are small but macroscopic and obey Newtonian classical physics. Of course rule out any supernatural influences.
2. Explain that determinism is true given these assumptions (it’s true pretty much by definition).
3. Put the burden of proof on anyone arguing for free will to explain why the features of quantum mechanics (QM) or some other non-classical aspect of nature can get you out from under the deterministic model.
4. Since nobody has done this convincingly, determinism is true.

Now I’ve made the point that a shortcoming of the worldview usually associated with science is its continued adoption of precisely this kind of outdated classical physical picture of the world. I’ve said we need to expand the naturalistic perspective beyond this picture.

But it still could be that even an expanded naturalism entails determinism. Specifically, I have argued that philosophical and scientific investigations (specifically QM) lead to a revised naturalistic worldview which includes a role for subjective experience at the most fundamental level of reality. But does this mean anything in terms of the free will debate?

Before going further, I should mention one method of using modern physics to argue for free will which I do not endorse. This idea, offered by Roger Penrose, Stuart Hameroff, and Henry Stapp, is that the human brain (uniquely in the macroscopic world) establishes and maintains quantum coherence (through a proposed feature of the structure of neurons), and this explains human consciousness and establishes free will. I don’t buy into this partly because many critics have made a persuasive case that the mechanisms won’t work. But also, I’m skeptical such a capability would have uniquely emerged in we humans (if neurons can “do it”, why not other cells or even single-celled organisms?). Rather, I am inclined to think that while human capabilities result from a special and complex mode of organization, they share a nature which is continuous with the rest of the world, grounded in the most fundamental level of reality. If we do have free will, it may be developed in us to a unique degree, but the kernel of what makes it work will exist in animals, plants, and so on, “all the way down.”

So, returning to the question: given what I believe we know about the nature of reality, including the fundamental role of subjective experience, is there true free will in the world?

Another way to frame the issue is this: if one accepts that there is are good reasons to believe all systems in the world have an element of subjective experience, do those experiences do any work?

I will take these questions up again shortly.

A Quick Take on Free Will

While I'm bringing up old philosophical problems, I want to also address the free-will/determinism debate. On the one hand, we experience ourselves as having free will in all facets of our lives. Scientific analysis, on the other hand, seeks to explain everything in a deterministic way. So yet again we have a seemingly irreconcilable divide based on the duality of perspectives between the subjective and objective views.

Now, my first problem with determinism is that human beings (and many other natural processes) are too complex for anyone to really be able to compute what happens next. There are just too many parts to the puzzle (and I think the problem goes beyond just developing faster computers). A key point to remember is that systems do not exist in isolation; a human being is incessantly acting on and reacting to an incredibly diverse environment, both physical and societal. So you would really need to model the environmental factors as well. In fact it may be that you need to have a model of the whole universe to get it right. Finally on this point, the idea of modeling the universe down it its most minute level of organization takes us back into the realm of quantum physics, where strict determinism appears to break down.

But, let me leave this sort of argument aside for now. Let’s assume that I could predict a human being’s behavior – perhaps a model of the brain at the level of the neuron is used and let’s say there is no need to look further down the scale or out into the environment. Would the success of this predictive model mean that free will is an illusion? I would say no. That conclusion would unduly elevate the third person explanation at the expense of the first person experience. Following from my earlier arguments, the first-person perspective is a fundamental, irreducible feature of the universe. It is as valid a source of knowledge as any. This argument leads one to say that both determinism and free will are correct (in philosophy, this position is called “compatibilism”). This is a difficult conclusion to hold in your head, of course. However, I think it helps in explaining again why the perceived dichotomies we keep running into aren’t necessarily real divisions in the universe, but rather they simply stem from the fact that we are a part of the universe trying to understand the universe from the inside. We simultaneously live the universe while also looking at it from the simulated objective perspective.

At the end of the day, I am sympathetic to this compatibilist “solution” to the free will/determinism debate, but I don’t think it is the whole story. The shortcoming in how this problem is posed is the implied determinist assumption that the “billiard-ball” view of physics I've mentioned before essentially holds. One assumes human behavior stems from biology which in turn is based on chemistry which is then based on physics; then we assume we understand what’s happening in physics. I don’t think we do yet. For a more complete understanding of how first person experience really reconciles with scientific explanations we need to have a theory of how this works at the most fundamental level of the universe. For now, I assert that while the particulars of the history leading up to a given moment certainly constrain our choices, how the next moment unfolds will reflect an element of genuine free will.