Where are we with this whole free will thing?

Haim Sompolinsky has written an excellent book chapter on the scientific view of free will and choice, pulling in good ideas from physics and neuroscience along with contemporary philosophical commentary.

I think this chapter might be helpful for neuroscientists outside of the lab. Often a dinner table discussion has moved to the idea of “quantum consciousness” or “quantum free will”. Often, someone will mention Roger Penrose, who has become something of a poster boy for this idea that quantum indeterminacy (eg. Heisenberg’s uncertainty principle) is one possible way that free will is really free. And then, people look around and say, “Well, you’re a neuroscientist. Do we have free will?” (And that’s when I take another big drink or bite while I figure out something semi-coherent to say.)

Sompolinsky does a nice job of evaluating such claims (in the end, he says we cannot rule out the possibility that the brain is an indeterministic system but it seems unlikely) and provides nice scientific insight. In his view, it is far more likely that the brain’s apparent randomness (eg. individual cell spike rasters vary across repeated presentations of the same stimulus) is more simply explained by thermal noise (think of varying channel gating properties) and chaotic brain dynamics. (Recall, a chaotic system is still deterministic; it simply exhibits aperiodic behavior due to exquisite sensitivity to initial conditions. It is difficult to predict the long-term behavior of chaotic systems. The more we know the initial conditions in detail, the better our prediction.) On the other hand, he argues that the relevant length and time scales for neurons (micrometers and milliseconds) are far larger by many orders of magnitude than those of quantum noise. Chaos might amplify such quantum events, but this is far from being the simplest, most parsimonious explanation. Given the current level of neuroscience understanding, this is almost idle speculation. Regardless of the (in)determinacy of the world, Sompolinsky effectively argues against any non-physical, purely mental (ie. dualistic) agent of causation.

Thus, in sum, the world and our brains might not be determined but, even given that, there’s no reason to believe we have any causative ability to change things in the sense of traditional free will. These observations seem right on the mark to me. I hope they bring some insight for others. Or at least a way to fend off the dinner-table-free-will-conversation barrage of questions.

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5 thoughts on “Where are we with this whole free will thing?

  1. This does come up fairly frequently. Thanks for the link and summary.

    As Sompolinksy mentions, Sperry argues that the mind is ’emergent’ from the brain and has ‘top-down causal influences’ on the lower-level neural processes in the way, say, that a crystal constrains the locations of individual atoms in its structure. A while ago I was trying to make sense of this claim and compiled a list of putative examples that various authors, including Sperry, use as cases of emergent phenemena outside the controversial realm of the human mind.

    The fact that classical (i.e., Boltzmann) statistical mechanics is so good at predicting the voltages across cells suggests to me that even for such lower-level processes we can treat brain as classical. However, this is not to say that there aren’t other quantum influences. It just seems people who make such claims either a) don’t know any neuroscience and aren’t aware of the wealth of explanatory resources already available, or b) have a philosophical ax to grind regarding free-will, consciousness, mathematical cognition, or some such. That doesn’t mean they are wrong.

    With people outside of academia especially, it pays to be undogmatic about this. While we have no good reason to think that human behavioral selection will be some unique thing in biology that requires fundamental new laws, answering their questions in a satisfying way will require a hundred+ or so years of systems and computational neuroscience.

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  2. I genuinely enjoy this site, but I can’t help but comment on:

    …”there’s no reason to believe we have any causative ability to change things in the sense of traditional free will.”

    Do you honestly believe this? Yes, I am a non-dualist, but this is not mutually exclusive with free will. We are a process unfolding in time. That means we bring our experience to every new situation. We make decisions, some random, and then learn from those decisions. Eventually, we have prior experience that we can choose to follow or ignore. Have you never thought “screw it, I don’t care what I’ve done in the past or what others tell me”? If you have just once, then how exactly are you lacking “causative ability to change things”? This idea that we need quantum influences to have free will is just nonsense (thanks physicists). Free will could very well be an emergent property of any brutally complex system with attractors that mutually influence one another (and might actually be able to be modeled one day w/o any need for considering individual atoms and such). I’ve never understood why any neuroscientist who understands chaotic dynamics (not just the intro idea of uncertainty in initial conditions , but the larger idea of attractors and connectedness) considers free will such a problem. Just b/c we don’t understand it and can’t model it doesn’t mean we don’t have it.

    If you don’t have free will, than I feel pretty sorry for you b/c you must have never decided to wait to pee or not sleep w/ someone who offered it or stopped eating sweets when you got fat. Free will defines us more than anything else. I am free to argue this point until I’m blue in the face and then concede it tomorrow if some super smart physicist replies with something about a cat 🙂

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  3. Sir K: when he mentioned ‘traditional’ free will by definition that means causal powers that are outside of the realm of natural processes. When we say ‘screw it’ and do something “random” it is still just your brain evolving according to natural processes. He can correct me if I’m wrong, but I think that is all he meant.

    The article he links to discusses the various things you mention such as chaos and emergence as providing a possible basis for decision making. I’m not sure we need such exotica to explain the psychology of decision making, but we have no idea how it works so nothing can be conclusively rejected yet.

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