Thursday, June 20, 2019

The Physics of Free Will

I know the topic of free will has been debated endlessly for millennia, and everyone has their own opinion.  However, I’ve read and searched endlessly, and I can’t find anyone who addresses or answers the following problem.

Let’s say that I perceive that I have the choice to press button A or B.  There are only three possibilities:
a) There is no actual branching event.  The perception is an illusion.  The button I press is entirely predetermined.  (That doesn’t imply that the universe as a whole is deterministic, but that indeterminacy is irrelevant to my perception of a free choice.)
b) There is a branching event, but it is quantum mechanical in nature.  In other words, the button I press actually depends on some QM event (whether you call it measurement, reduction, or collapse), so while the outcome is not predetermined, it is random.  The perception that a branching event was about to happen was correct, but the perception that I can control it is an illusion.
c) There is a branching event, and my free will caused the outcome.

In case a), my “choice” is simply a prediction about the future.  But there are several problems with this:
1) Why would I ever perceive as possible an event that is actually impossible?  (If pressing button A was predetermined, then pressing B is an impossible event.)
2) What is the advantage of making a prediction if awareness of the predicted outcome will not affect anything that will happen in the future?  In other words, if I can’t DO anything to change anything (because I don’t have free will), what’s the point in predicting? 
3) What is the advantage of perceiving free will when I am actually making a prediction?  When I drop a ball, I predict it will accelerate downward toward the Earth.  But imagine if I (falsely) believed I had free will over that ball... “OK, am I going to drop the ball UP or DOWN?  Hmmm... today I’ll decide to drop it DOWN.”  What would be the point of that false perception? 

The case of b) isn’t much better, because my “choice” is, again, just a prediction about the future (possibly coupled with measurement of a random QM event).  The same problems arise.

Note that my perception of free will is limited to my body, and not even my entire body (for example, I don’t think I can consciously control my digestion process).  In fact, I only perceive “free will” with regard to a few aspects of my body, such as motions of my hands and fingers.  But what is true is that I have never EVER once observed the experience of NOT having free will over those parts.  For example, I have never decided to raise my right hand, but then my left hand rises instead.  I never raise my hand and then say, “I didn’t do that!” 

But that COULD have been the case.  I could have been born into a world in which I just observed things happening... where my body was no different from a dropping ball or a planet orbiting a star... where it’s just an object that moves on its own and I experience it.  In other words, why am I not just experiencing the world through a body that moves on its own as if I were just watching an immersive (five-sense) movie?  It’s not like we need to believe in free will.  For example, we are perfectly fine watching movies or riding roller coasters, full well knowing that we can’t control them.  Why couldn’t we just be passing through the world moment-to-moment, just experiencing the ride, without any perception that we have free choices?  In other words, if a) or b) above is true, we need to explain WHY I perceive the freedom to press button A or B, but also why my choices are always 100% consistent with the outcome.

That’s a real problem.  Because now we have to explain why the universe would conspire to:
* Fool me into believing that I have a choice when I don’t; AND
* Fool me into believing that the outcome is always consistent with what I (mistakenly) thought I chose!

Why would the universe fool us like that? 

As an aside, please don’t answer with “compatibilism,” which is the philosopher’s way of avoiding the question of free will.  You can look it up, but I regard it as a non-answer.  Even famed philosopher JohnSearle agrees that philosophers haven’t made any progress on the free will question in the past hundred years.


  1. I was blown away by your papers on Arxiv this year and just found your blog. Like you, I also wonder why everyone isn’t discussing this more seriously, although I am sure they will eventually. I also subscribe to Penrose’s theory (and yours) that consciousness must be related to the quantum realm. To me, that is the only way “free” will could ever exist and I don’t see why the universe would trick us or any lifeform either. That said, that idea of the universe tricking us makes my mind go down some very strange paths about the nature of reality.

  2. Thanks for your comments! Physicists felt much freer to discuss the deep issues a century ago, but because there really isn't any funding for these questions (outside of philosophy), few if any physicists are seriously working on these problems. But they're big and important problems, so it's just a matter of time before the winds change.

  3. It's not clear what you mean by option (c), "There is a branching event, and my free will caused the outcome." If an outcome has a sufficient cause it means that if the cause occurs the outcome necessarily occurs, so there is no branching. It doesn't matter to the logic of the argument if the cause is natural or supernatural: either the outcome is caused or it is not caused.

    1. Interesting point. My point in option (c) is that my free will IS the cause. Of course, if you want to argue all my free choices are caused by other things, then you've just argued for Compatibilism, which (as I stated in the posting) I regard as the philosopher's non-answer. You are right -- if free will is itself not a cause, then option (c) simplifies to option (a)… in which case there is no branching and the world is deterministic. But that still doesn't answer the questions I posed... e.g., why would the universe fool me into believing that I have free will (or, if you like, that my free will is a cause and that I could have chosen otherwise) when I don't?

  4. Firstly, the universe is not under any obligation to avoid fooling us. Because the Earth looks flat does not mean it is flat.

    Secondly, I don’t think we are fooled in thinking we could do otherwise when we make our choice. We COULD do otherwise under different conditions, such as if we want to do otherwise. If we could do otherwise under the SAME conditions that would mean our choice is random. Random choices might be OK if we are choosing a flavour of ice cream but in general we could not survive if this is how our brains worked.

  5. "I never raise my hand and then say, “I didn’t do that!” " Have you read about split brain patients experiments ? You make a freaking lot of assumptions based on your own perceptions, how scientific is that ? Have you ever looked at cognitive biases ?

    "Why would I ever perceive as possible an event that is actually impossible ?"
    Because our brain are very limited at guessing correctly the outcome of events ! If pressing button A was predetermined, maybe I just don't have enough knowledge about the environment to predict it ?

    "What is the advantage of making a prediction if awareness of the predicted outcome will not affect anything that will happen in the future ?"
    This is not the right question to ask on many levels, first of all we already know our predictions are affecting our environment, the useful question is: do we predict and choose out of freewill or randomness, or do we have a predictable consciousness (and we already know our mind is partially predictable at least !) ?

    "What is the advantage of perceiving free will when I am actually making a prediction ?
    Do you have the choice of perceiving it or not ? Indeed, what difference does it make ? Getting to improve the probability of success of our predictions is a mean to become more relevant, powerful and effective. What's more ?

    Were you raised in a religious or spiritual family ? Why do you even research all this stuff ?


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