Dennett and the “Little People” #3

Below is the David Hamill piece from the Free Thought Prophet blog that triggered the two … previousposts as well as a lot of comments and tweets. Most of my earlier thoughts concerned the Jerry Coyne post given as a reference and the linked Dan Dennett Big Think video. In addition to that, we have the inevitable “baying mob” of commenters around Coyne and the various linked YouTube videos on the topic. To paraphrase innumerable comments, the new-atheist scientistic world and its bulldogs believe:

“The behaviour of all matter and energy in the real world is determined by the laws of physics. Therefore free will does not exist, it is entirely illusory. End of.” (My own paraphrase. There is a major presumption, if not dogma, behind that “therefore”.)

Anyway, to the matter at hand. The quoted sections below are the full text of the Hamill piece, with my critique inserted between. I love the irony that a blog dedicated to free-thought is in denial of our freedom of will to think and act. But, let’s go …

Hamill’s text in blockquotes:

Richard Dawkins, Sam Harris, Daniel Dennett and Christopher Hitchens are often referred to as the ‘Four Horsemen Of Atheism’. They haven’t had too many public disagreements but perhaps the most prominent ongoing dispute, relates to free will. This is a topic that is not unrelated to religion, of course. Most of the world’s faithful are taught that the difference between eternal paradise and eternal agony, lies in how we each exercise our free will.

OK, not unrelated to religion, but there are two separate issues tangled-up since original Cartesian dualism as well as two further separate religious angles. The original reason for seeing “will” as something outside the “physical” world, was partly to give somewhere for will to reside since determinism appeared to have banished it from the natural world, particularly so that God’s will could be saved in this supernatural space. Exactly how the supernatural mental world could act upon the natural physical world is left unexplained – essentially, miraculous. Moral teachings on how we should use our will incentivised by the rewards & penalties in the this life or the next were another artificial religious device. Obviously these are connected, but it is not necessary to bring any religious interest into this human free-will debate, where our interest is really the question “does the natural physical world really banish free will?” The science vs religion wars have thrown the question into the spotlight, and raised the dogmatic stakes for the new-atheists, but …

Either there is free will in the natural world or there isn’t. This is not (need not be) a religious question.

Sam Harris is a strong determinist and he argues that free will is an illusion. That is, since the contents of the human skull are no more immune to the laws of physics than any other matter in the universe, our behaviour is always exactly commensurate with deterministic causality. Dan Dennett agrees that science comprehensively rejects the mind-body dualism on which religious ideas of free will are based. However, as a compatibilist he also argues that free will can be reconciled with the deterministic physical laws.

Fair enough. But the key thing here is the distinction between strong (or hard) determinism and the kind of determinism that might be compatible with free-will. It is a definitional question about what we really mean by determinism, and the kind of free-will whose existence is worth considering. [And in fact, contrary to polular myth, Harris doesn’t actually say that free will is an illusion …. but that will become apparent.]

As it happens, I’m convinced by the determinist argument and I find compatibilist positions to be rather slippery.

No surprise. I’m happy with determinism too, but open to working definitions of what we mean. Clearly with a hard – dare I say dogmatic – view of determinism, compatibilism looks like a slippery concept. That slipperiness simply shows that we have some work to do on agreeing definitions. (Let’s not forget that both philosophically and physically even causation is hard to get a fundamental handle on. Seems to me the slippery concept here is determinism itself.) Working on definitions as part of our discourse, rather than as pre-defined beforehand, is fundamental to Dennett’s ways of argument and explanation by exploration and discovery – the evolution of species of argument.

The conclusion that our decisions are determined by the matter in our brains obeying the laws of physics, rather than by some ethereal mind or soul, is one that is of great import. Since the dualism on which so much of religion depends is false, explaining the implications of that would seem to be a good use of any philosopher’s time. Instead, it seems that compatibilist philosophers quite often prefer to spend their time inventing new definitions of free will, which can accommodate determinism.

Not sure this adds anything to the free-will debate, except to express annoyance at philosophers. Obviously philosophers and theologians can debate the natural vs supernatural dualism of religion too, but our topic here is free-will in the natural world. Rather than “inventing” new definitions, the whole progress of natural science is one of discovering and evolving new definitions and explanations.

I think that a better analogue for our subjective experience of volition, is found not in new definitions of free will, but rather in computational intractability. When discussing this topic, philosophers often like to return to a famous Austin thought experiment involving a golfer.

OK, now we’re getting onto the topic at hand. I personally use the Wegner example of a top-class tennis-player returning a serve, where not only the inevitable-repeatability aspect becomes apparent, but also the largely pre-determined and fine-tuned (supervisory free-won’t) aspects are also apparent.

If a great golfer misses a simple putt, should we consider that she could have holed it, based on some degree of freedom that she had? Alternatively, if every atom in the golfer is returned exactly as it was before the missed putt and the shot is replayed, must she miss it again, as the invariant laws of physics consistently produce the same results?

Not sure this is the key question affecting free-will. Although there appears to be an inevitability of the same deterministic result, everything hangs on the “if” thought-experiment in that second sentence. Not just if every atom, every blade of grass, every spec of earth, but how every atom not to mention every historically if and how of every entangled force and particle in the cosmos. Gödel might have something to say about this too. (I’m not heading to some mysterious “quantum” explanation for proto-consciousness, simply pointing out the enormity of that IF, especially since we’re about to consider tractability.)

Many debates around free will and determinism have considered this question (including the often heated exchanges between Harris and Dennett).

That was true in 2014, but don’t forget that the Dennett-Harris exchange returned to respectful dialogue in 2016.

Considering the issue from the perspective of computational intractability, may allow for a different starting point.

OK. Something new, and the particular point of this Hamill piece. Computational tractability and predictability.

For example, if a rain cloud moved over the golf course, could we calculate which blade of grass will be first to be struck by a raindrop? Certainly, the rain cloud does not have free will, so there will be one blade of grass that will be first to get wet and that will be the result of deterministic laws of physics acting on the relevant atoms and particles. If we were able to observe which blade of grass was struck by a raindrop first, and then replace all of the atoms in the atmosphere exactly as they were before the rain started, what would happen if we then replayed the events?

Of course, since the laws of physics don’t change, the same arrangement of atoms will give rise to the same results.

Hmmm. That’s some claim. Partly again, because of the enormous IF in that repeatable situation, partly because there will be chaotic aspects in predicting patterns of statistical distribution of trajectories of populations of raindrops, not just the same one raindrop, and partly because we are about to come to some tractability questions in any computation to predict the behaviour of raindrop(s).

Quantum indeterminacy can’t deliver free will either. Even if relevant at the scale of the particles and molecules that exist in human brains and rain clouds, quantum indeterminacy would offer some randomness but no free will.

Not sure where we’re headed here? Has anyone ever suggested clouds and raindrops have free-will? Some (Penrose-Hameroff) have proposed quantum-level mechanisms consciousness, but there’s nothing being suggested here by Dennett (or myself).

However, the vast number of particles and interactions involved in rain clouds, and the even greater complexity of human brains, means that any calculation to predict either outcome would be intractable.

I believe that to be true, as noted above, given the scale of variables and degrees of freedom.

Even if we could measure the position and momentum of every relevant atom in advance, there will be no more practical way to see where the raindrops fall, or where the putt comes to rest, than to allow the laws of physics to play out and just watch.

OK, good, so we’re agreed on this. Empiricism rules, and involves the same golfer – body and soul – on any given day, another day when the starting point can only be approximately the same, not the literal particle-level identical re-run. The tractability question applies just as much to that “even if” starting point as to running the computation.

Trying to prove mathematically whether the brain state of the golfer will result in her sinking her putt or not, is tangentially related to Hilbert’s Entscheidungsproblem (decision problem). In our case, the decision problem asks if we can analyse the complete configuration of the golfer’s brain along with the laws of physics, and prove in advance whether her putt will be holed or not. Alonso Church and Alan Turing showed that there is no solution to the Entscheidungsproblem (a previous blog on this site discussed Turing’s 1936 paper on the topic, which introduced the Turing Machine).

For example, if we view a rain cloud as a Universal Turing Machine that is configured to calculate the interactions between all of the relevant particles, then we cannot prove in advance which blade of grass will get wet first. The only practical approach is to ‘run the program’ on the machine (the cloud) and observe which blade of grass is first struck by a raindrop.

Similarly, if we consider the golfer to be a Universal Turing Machine, then Turing’s 1936 paper on computable numbers shows that even if we could know her complete configuration in advance, we still could not prove what the outcome of the putt would be.

OK, my preference is to translate Hilbert as “the decidability problem” (it’s about computational decidability, not about a mind making a decision, necessarily), but no issue with any of this.  Dennett too uses UTM machine views of ourselves and our minds, but this is saying nothing about free-will?

Additionally, if the golfer actually wanted to perform the full calculation to work out what kind of putt her brain state would produce, that would take exponentially more time than just taking the putt.

True, but I believe this is irrelevant to how decisions to act are made. Much more stochastic, heuristic, statistical prioritisation of sub-conscious and consciously significant components of making a putt. (As I say, Wegner uses the speed of reaction of the receiving tennis-player to illustrate the enormous short-cuts to any actual calculation.)

That is, the problem is computationally intractable not just in practice but in principle. The only way to discover the outcome is to ‘run the program’ on the machine (the golfer) and watch where the ball goes.

Again we are talking about the intractable predictability of the problem. What about free-will?

In Programming the Universe, Seth Lloyd describes the implications of Turing’s Entscheidungsproblem proof as follows …

“… once we set a train of thought in motion, we do not know whether it will lead anywhere at all. Even if it does lead somewhere, we don’t know where that somewhere is until we get there.”

The reason why we can’t predict the actions of a human being with full confidence, is not because people have free will or an ethereal soul. It is because either under a classical deterministic universe or under a quantum probabilistic universe, the problem is computationally intractable.

OK. This simply says that this unpredictability has nothing to do with free-will. It says nothing about free-will?

Free will is an illusion and our actions are fully determined by the laws of physics.

How does this even remotely follow from the previous statement(s)? This is incidentally the position of all the bulldogs in the Coyne and YouTube comment threads noted above. A prejudiced statement, but no kind of proof or explanation.

The path of a golf ball rolling on an undulating green is also fully determined by the laws of physics and easily predictable.

I doubt that. Determined, but not easily and certainly not fully predictably. More reasonably, to some precision within statistical bounds of predictability and chaotic attractors. Even to build the set of would-be deterministic rules – eg, the possible states of every blade of grass? – would be intractable and need to involve judgemental and empirical short-cuts.

However, Turing distinguishes between some problems that are computable and others that are not. The path of a golf ball on an undulating green is an easily computable differential equation. The proof of a decision problem for the brain state of Austin’s golfer either sinking or missing a putt, is impossible in principle.

Austin’s golfer will miss the putt every time. Even if before each replay, a computer is given her complete configuration in advance, Turing shows that it will still always be impossible to prove the outcome beforehand. Each time we replace every atom in the golfer exactly as it was, we will still need to replay the putt by ‘running the program’ on the machine (Austin’s golfer) and watching her miss.

Even if true, this simply seems to say, she will always miss, even though we can’t prove it. Does it say anything about free-will?

Religion says that god gave man free will,

I think we’re well past this intelligent-design / creationist position in this debate? Anyone rational person who believes in free-will – certainly Dennett – believes it to be a naturally evolved capability of sentient beings.

Turing shows that it only seems like we have free will, because we’re computationally intractable and so we cannot know what we’re going to do next.

No he doesn’t. He simply shows that whatever free-will we do (or don’t) have, the outcomes of our decisions and actions, and all the deterministic processes of physics, are not fully predictable. Free-will or not.

Turing: “We can only see a short distance ahead, but we can see plenty there that needs to be done.”

And Turing agrees with me, it seems. How could anyone see free-will as some superhuman capability to direct and predict the entire future locus of every particle (and sentient being) in the universe. Obviously, that kind of free-will doesn’t exist outside some hypothetical omniscient god or thought experiment. It would be a straw man to suggest any rational person ever suggested it did.

The issue left unaddressed here is:

IF the universe is deterministic, how can we explain free-will?

Now that’s an interesting question.


[Post Note: A new source for me on this is Max Tegmark – on the trail of both AI and Consciousness – here on “Substrate Independence”.

“consciousness is substrate-independent twice over!”

Determinism crosses levels and achieves independence from earlier levels (Hofstadterian strange-loopy. Pirsigian too? Woohoo!).]

[Post Note: Another new source Fern Elsdon-Baker at Newman Uni. Confirming even atheist believers in Evolution struggle to accept evolutionary explanations of consciousness (and will) – but as I say that’s because the more extreme “scientistic” struggle to accept consciousness anyway.]

Also published on Medium.

5 thoughts on “Dennett and the “Little People” #3”

  1. This puts into words what’s been bugging me about the no-freewill claims for years now. I don’t trust my intuition about most subjects these days but hard determinism seemed to go against my own very nature and experience. This makes much more sense to me and is logically sound as far as I can tell. Thanks Ian.

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