Thursday, January 31, 2019

Can free will be grounded in quantum mechanics?

Robert Kane famously physicalistically grounds free will in quantum events in the brain. Free choice, on Kane’s view, is constituted by rational deliberation involving conflicting motivational structures with a resolution by an indeterministic causal process—a causal process that Kane thinks is in fact physical.

Here is a problem. Suppose Kane’s view is true. But now imagine a possible world with a physics that is like our quantum physics, but where panpsychism is true. The particles are conscious, and some of them engage in libertarian free choices, with chances of choices exactly matching up with what quantum mechanics predicts. The world still has people with brains, in addition to particle-sized people. The people with brains have particles that are persons in their brains. Moreover, it turns out that those indeterministic causal processes in the brains that constitute free choice are in fact the free actions of the particle-sized people in the breains.

All of Kane’s conditions for freedom will be satisfied by the people with brains. For the only relevant difference is that the quantum-style causal processes are choice processes (of the particle people). But these processes are just as indeterministic as in our world, and it’s the indeterminism that matters.

But the actions of the brain possessors in that world wouldn’t be free, because they would be under the control of the particle people in the brains. We could even suppose, if we like, that the particle people know about brains and want to direct the big people in some particular direction.

One could add to Kane’s account the further condition that the indeterministic causal processes in the brain are not constituted by the free choices of another person. But this seems ad hoc, and it is not clear why this one particular way for the indeterministic causal processes to be constituted is forbidden while any other way for them to be constituted is acceptable. The details of how quantum indeterministic processes work, as long as they are truly indeterministic and follow the quantum statistics, should not matter for free will.

This problem applies to any physicalist account on which free choices are grounded in quantum processes.

There is a way out of the problem. One could accept a pair of Aristotelian dicta:

  1. All persons are substances.

  2. No substance is a part of another substance.

But it is not clear whether the acceptance of these dicta is plausible apart from the fuller Aristotelian metaphysics which holds that all substances are partially made of non-physical forms. In other words, it is not clear that acceptance of (1) and (2) can be well motivated within a physicalist metaphysics.

8 comments:

entirelyuseless said...

"But the actions of the brain possessors in that world wouldn’t be free, because they would be under the control of the particle people in the brains. We could even suppose, if we like, that the particle people know about brains and want to direct the big people in some particular direction."

No, it is the actions of the particle people that wouldn't be free, because they would be under the control of the normal people. We could even suppose, if we like that the normal people know about the particle people and want to direct them in some particular direction.

Neither argument works: both the particle people and the normal people would be free, if it is the indeterminism that matters. And either indeterminism matters or it doesn't. And if it doesn't, then it does not matter for free will if determinism is true.

Brian Cutter said...

Cool argument. An interesting variant of this sort of concern with Kane's view comes from thinking about cases where the particles in my head are entangled with the particles in your head in such a way that, although both our choices are physically indeterministic, there's a nomologically necessary connection between what I choose and what you choose. In this case, Kane's account predicts that we both act freely. But I think there's an intuition that if two choices are each non-derivatively free, then neither can be necessitated by the other.

Alexander R Pruss said...

Brian:

I think the entanglement case while interesting is different, because there my choice is significantly causally affected by something that isn't a part of me, namely your quantum system. (How the causal connections work is of course a hard phil of QM question.)

eu:

I am thinking that the particle-people's choices are explanatorily prior in the physical order of things, so there is an asymmetry.

Wesley C. said...

A few wonderings about free will:

1) One thing I've been thinking about is what the metaphysical principles are behind indeterminstic causality - at least for Thomistic accounts of free will, the will is free because it's goal is goodness in general, or infinite goodness, and so finite or particular goods can't determine it - the only object that determins the will is infinite goodness, which is God. So while the will can have particular goods as goals, by nature the will can't be determined to those. In other words, the will in acting isn't attracted with absolute force of necessity, instead the attraction isn't necessitated but finite.

Another way of putting this is that the will doesn't give itself completely to that thing in an absolute sense, or that it can't fully end in it. So couldn't something similar be said of indeterminism in general - including physical objects such as electrons or 6-sided die? Even though they don't have inherently immaterial powers, nor are they alive, something about them makes it such that they aren't determined to any particular effect, but the inclination or attraction is finite or less-than-necessary.

What do you think?

2) A similar but opposing idea would be that indeterministic causation is a higher perfection that only immaterial things possess - the will's immateriality, including it's higher goals of universal or infinite goodness, is what allows for indeterminism, so material things like electrons or dies can't have it. Might as well say the apparent indeterinism is really just evidence of angels governing the world.

But on the other hand, indeterministic causation might be a universal perfection that all grades of being can possess, which reflect God's freedom.

Scotus for example argued that self-motion wasn't just a trait possessed by the immaterial will, but material substances could also have it - an example is rocks which fall down after being thrown, due to an internal active power actualising an internal passive power. He did though distinguish the self-motion of the will from the self-motion of material substances, arguing that they don't have free will or the immediate higher self-motivity that the immaterial will has since it isn't composed of material parts. But self-motion would in general is conducive to dignity insofar as getting something for yourself and by your own power is a higher perfection than having to rely on something else to actualise your needs.

In a similar way, couldn't it be argued that indeterministic power is also something even material things can possess, just like self-motion, especially if we view indeterministm as being a higher perfection than determinism because it reflects God's freedom, power and creativity more?

Of course, free will would be radically different from the motion of electrons, or the results of 6-sided dies - those are indeterministic only in some respects (i.e. when to shoot out a photon, or being limited to only two movements such as up or down), while the will is much higher as a faculty, being not only alive but also is a genuine power over different causal events, and is a limit case that can't be analysed through anything else.

What do you think?

Wesley C. said...

Now after thinking about indeterminism a bit, I think a possible account of the principle that makes quantum events and fair dies indeterministic could be similar to what makes the will indeterministic - including multiple effects under a greater unity in some way.

So the will is directed towards goodness in general, as well as infinite goodness, and finite particular goods fit into the category of goodness universally, or are related to it in some way, which is why the will is determined towards God alone, and indetermined towards created goods. You could say that finite particular goods are all united under the aspect of goodness as such, or are seen under that aspect or background, and it's this primary orientation towards goodness as such which incorporates particular goods under its roof, which allows for indeterministic choices.

Something similar may be going on with lower-level indeterminism, which might help explain it --- an electron is determined to shoot out a photon in 10 seconds, and any particular second of that is united under the more general roof of those 10 seconds, which is why the electron isn't determined towards any individual second, though it can and will choose one of them. So what allows the electron to be indeterministic is the primary generality of its final cause, which unites the specific seconds under its roof. This can be applied to any other indeterministic material cause.

If this is true, it looks like the reason why indeterministic causes are indeterministic is because they possess their final causes and effects more intimately and eminently, and with a greater union or principle of unity enveloping them. The will would then be a much higher example of this general principle, where the will is oriented towards goodness in general and so is much more universal in scope than electrons. Even more importantly, it's also alive and possesses its final causes and effects with much more immanence and substantial unity - it's literally a faculty of a self-aware personal being whose essence requires greater whole-to-parts union than non-living things. And what's more, the will is closely related to the intellect, which possesses the very forms of things in an immaterial manner and can know indefinitely many things in principle, which is far superior to merely having a general final cause that includes a few specific instances within it.

In other words, the indeterminism of free will seems more perfect than the indeterminism of quantum physics.

What's more, this may even imply that a cause is more truly a cause the more indeterministic it is - precisely because it possesses its final causes and effects in a more eminent and united way than a deterministic cause ever could. God would then be the ultimate apex of all of this, since He is the most excellent indeterministic cause there is as He possesses all possible beings and effects in the most intimate, eminent and united way possible.


What do you think?

Wesley C. said...
This comment has been removed by the author.
Wesley C. said...

What do you think of this possibility as a potential explanation of the metaphysics of indeterminism as described in the above comment?

Alexander R Pruss said...

It sounds fairly plausible.