A good few years ago I read The Emperor's New Mind by Roger Penrose. Having recently read some philosopy primers I was wondering about the links between this book and the question of free will.

From what i remember the final (speculative) argument went

  1. (Roger thinks) there is free will
  2. Where might free will be located?
  3. There are microtubules in biological cells
  4. These are about the size where quantum physics becomes classical
  5. That's a mysterious part of physics that we really don't know much about
  6. Therefore that's a good candidate for free will

While that might seem a flippant summary - it isn't meant to be. I was quite taken with the argument at the time.

So my questions are

  1. Has Roger Penrose put forward a form of dualism there. Has he located a ghost in the machine or is this a different argument?
  2. Did this argument ever go anywhere. Did anyone build on this or was it just some speculation that went nowhere?

Also - it's possible (likely) that I have completely misunderstood the Emperor's New Mind conclusions. Please feel free to correct me.

  • I have no deep understanding of this discussion, but I if find this kind of argument contradictory. As.. if there is free will, it is determined by the nature of some physical reality. It reduces human beings to pure material (bio-physical) entities.
    – Tames
    Jul 19 '12 at 16:57

Penrose's idea fell afoul of well-verified contradictory information. First, the mechanisms for functioning of neurons are quite well worked out, and do not require microtubules for signaling (only for structural properties, which change meaningfully on time scales longer than a choice that we percieve). Second, microtubules in cells are at relatively high temperature, immersed in solvent, and connected to all sorts of proteins and other gunk--in short, an absolutely terrible place to maintain any interesting properties not well-described classically, and an even worse place to transmit that state over any interesting distance. I'm not sure whether Penrose is even bothering to propose the theory any more; that seems to have fallen mainly to Hameroff. The various hypotheses (perhaps that is too generous--pseudoscientific babblings is nearer to the mark at this point) are generally regarded among both physicists and neuroscientists (those whose opinion I know, anyway) as wrong.

Since the hypothesis is, so far as we can tell, completely baseless, it is hard to know whether it's dualistic or not--unless Penrose comes right out and states what he intended, it's rather hard to infer such things from an incorrect theory, because the answer may depend on the fix. (For example, one could "save" a broken non-dualist theory by becoming a dualist.)

  • That's great. Satisfies my curiosity and all that. I noticed that Penrose continued with these theories in his Shadows of the Mind follow up but looks like neither of the books would now be worth reading in the light of your comments. The stuff on the Turing machine (and Godel) in ENM are really excellent IMHO but sadly the central premise is blown out of the water. Still interesting to see how these kinds of theories wax and wane. Science I guess. Jul 24 '12 at 8:07

As far as I understand, in Emperor's New Mind, Roger Penrose puts forward the idea that certain elements of the laws of physics, yet unknown, might be deterministic but not computable. Deterministic in the sense that future is uniquely determined by present. Non-computable in the sense that no computer can calculate the future.

Penrose suggests that physics of the mind must borrow from these deterministic but non-computable laws.

As a hypothetical example of such a law of physics, Penrose uses Turing's halting problem. Suppose the state of a hypothetical universe at time t depends upon two natural numbers (m,n). Let the state of the universe the next second evolve according to a physical law which says- If mth Turing machine halts when fed with the number n, then the new state of the universe will be (m+1,n+1), and if it does not halt, then the new state will be (m+2,n+3). Since there does not exist any algorithm that can solve the halting problem for all m's and n's, hence the future of this universe, although completely deterministic, cannot be simulated on any computer program.

Now coming to free will, Penrose suggests that the human mind is deterministic but not computable. So, the only way to know how a person will behave in a situation is to put them in that situation.

It is interesting to note that if such non-computable laws exist in our universe then prediction of future will become impossible for anybody relying on computation. The only way to know the future would be to wait for it, unless one can somehow harness these computation defying physical laws to build a 'next level computer'.


It turns out that Penrose is an incompatibilist. Compatibilists have various proposed ways that indeterminacy might not be required for free will at all.

I was an incompatibilist for a long time, certainly when I read Penrose's book. I didn't even know there were compatibilists at that time, and it is not obvious to me that Penrose knew there were compatibilists.

The thing that finally knocked me off my incompatibilist horse was that MOST of free will doesn't feel like random or arbitrary choice. Certainly I can argue that my particular choice to type an extra % in the middle of my document was pure free will. But what about my choice to not eat the box of cookies that looked so appealing? Or my choice to try a shorter pilot code when I am trying to make a radio acquisition system that works even when it is moving? These are intelligent choices. I want my choices to be right. Right compared to what? Presumably I run my best internal model of what would be right in order to "choose" those choices.

Reading Penrose, it seemed to me unlikely that a phenomenon as robust as human and animal choice would depend on some carefully balanced physics that allowed the randomness of a quantum process to make the final "choice." Further, it was clear that most of my "choices" are made in highly constrained ways, at least when I am doing it right. And so I am not sure I concluded to be a compatibilist, as much as I retreated to a position of agnostic, but probably compatibilist. It is easy enough to build deterministic processes that look like random number generators (all computer languages have random number generators like this). Further, "free" choice is harcly "random" choice.

You can find some interesting modern discussion on this topic over here. Free will vs determinism may be a question that needs to be dissolved more than it needs to be answerd.

  • I think it'd be pretty unfair to label as someone, in this instance Penrose, under an umbrella term of -IST. Jul 20 '12 at 8:15
  • @Mahmud I wonder if Penrose would agree?
    – mwengler
    Jul 20 '12 at 13:18
  • 1
    Thanks for the answer. I'm now not convinced his argument was free will. He was arguing that you couldn't artificially recontruct a mind due to the indeterminant nature of the human mind as outlined above. As you say - just because something is interdeminant doesn't mean it's free will. But i do think he was arguing for a non-mechanist somekind of something somewhere in the human mind. Dualism without free will? I don't know. Jul 23 '12 at 13:12

I did not read Penrose's book. Maybe the following thoughts are of use.

According to Intequinism today, it is not possible to generalise about free will and determinism. It is different for each person and place in the sense that, the more fake news exists in a mind, the less free will that person has. The less fake news exists, the more free will exists. By the way, a realisation in Intequinism was, to say "never generalise", is a generalisation, and is therefore a contradiction (fallacy).

Part of post-modernism's paradigm is fake news, because post-modernists usually argue against the idea Truth (that truths are correspondences). They also, if i comprehend them correctly, argue free will doesn't exist because they usually do not respect laws about not-doing evil to all. When laws about not-doing are transgressed, they have conviction that punishment cannot be motivated because of no free will. "The" conviction for no free will is partly caused by their motivation for no punishment. I think fake news reduces free will because without sufficient true information, informed decision cannot be taken. In a sense thus post-modernists have partly succeeded in their project of causing chaos, in which free will is less relevant than in ordered societies.

Minds full of fake news react more with instinct than with thinking, because true thinking can only be done with true puzzle pieces in mind.

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