Tuesday, January 11, 2011

Don’t Assume Quantum Physics Doesn’t Matter

85 years after the formulation of quantum mechanics, it is still often assumed that distinctively quantum phenomena have no role to play in explaining life or mind. I think this assumption is unjustified.

Clearly scientific models have done an excellent job across a variety of fields (including molecular biology and bio-chemistry) with no need to invoke quantum effects like superposition and entanglement. It’s almost as if nature was tempting us to believe we live in an essentially classical world -- with quantum physics safely relegated to the laboratory. But now we’re beginning to learn about the exploitation of quantum effects in biology. While we already had an in-depth understanding of photosynthesis, it turns out that the process is made much more efficient by utilizing quantum coherence. I think this example shows that progress in quantum biology is made challenging by the technological sophistication needed to detect such processes -- but it’s also true that we won’t discover them if we assume they don’t exist. Hopefully recent results will spur many new research programs in this area.

We can try to speculate in advance of the science: when done well this can suggest avenues for research (I think Stuart Kauffman, the subject of the last post, does a fine job of this). But I wonder if the ubiquity of a philosophical materialism seemingly inspired by classical physics holds us back. For example it’s surprising to me that scientifically-oriented philosophers would still defend the thesis that the human brain/body system is not only (for all practical purposes) classical but deterministic, despite our grounding in quantum physics. For example Daniel Dennett, in his book Freedom Evolves, argues for determinism and compatibilism about free will. In doing so he assumes at the outset that the details of microphysics do not matter until proven otherwise. I thought that was backwards: why wouldn’t natural selection exploit the indeterminism of quantum mechanics and its other distinctive features? The goal should be to figure out how and to what extent. (It’s also possible QM was needed to “get off the ground” – some ideas toward solving the problem of the origin of life suggest this).

Now I know part of the problem is that many of those who would invoke QM to explain the human mind in particular engage in rampant speculation or worse. In particular we are afflicted with some popular “new-age” authors who have an unfortunate propensity to link quantum mechanics to wishful thinking about paranormal abilities and the supernatural. This clearly taints the topic in the eyes of many. But there’s a false dichotomy at work here: the fact that QM fails to give us magical powers doesn’t make it irrelevant. On the topic of free will, a false dichotomy also seems to prevail: it’s true we have evidence that the folk conception of free will is deeply flawed, but it doesn’t follow that our brain/body systems have no freedom.

While the evidence is preliminary and the effects may be subtle, I predict that 85 years from now it will be well understood that non-trivial quantum effects play an important explanatory role in life and mind.

19 comments:

Crude said...

I suspect one problem with looking to the quantum realm to explain aspects of the mind is that said realm not only isn't as easy to understand as the classical, but there's the looming possibility that certain aspects of it are going to forever remain mysterious. Worse, it's a variety of 'mysterious' that may not establish spooky/weird concepts, but does seem to open the doors to such.

Henry Stapp, who normally seems to try hard to keep those "New Age" sorts at arm's length, did write a fairly recent paper speculating on 'post-mortem surival' with this conclusion:

In summary, the central point of this paper is merely to point out that the elaboration of orthodox quantum mechanics that achieves the most commonsensical solution to the biocentrism problem parallels an elaboration that naturally accommodates personality survival. Neither of these elaborations appears to require any basic change in the orthodox theory. But both require a relaxing of the idea that physical and mental events occur only when paired together.

In light of these considerations, strong doubts about personality survival based solely on the belief that postmortem survival is incompatible with the laws of physics are unfounded. Rational science-based opinion on this question must be based on the content and quality of the empirical data, not on a presumed incompatibility of such phenomena with our contemporary understanding of the workings of nature.


I suspect the problem isn't usually that "QM fails to give us magical powers", but that QM opens doors that classical physics seems to shut, and some people prefer certain doors to remain closed.

bloggerthinker said...

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I contacted you because your blog's focus seems to be philosophy and because "Building Stronger Communities" is intended to analyze the fundamental philosophies and goals of individuals and community. Perhaps you might be interested in such analysis.

The purpose of the analysis and for "Building Stronger Communities" is my experience that examining fundamental community philosophies seems to reveal overlooked conflicts between what we want in our communities and what we establish in them. Hopefully, better understanding of the two can enhance individuals' and communities' goal and strategy effectiveness and well-being.

I thank you for your time and hope you'll stop by "Building Stronger Communities" to weigh in on its perspectives. I look forward to hearing, or reading, from you and wish you the best.

Pierre

Steve said...

Hi Crude:
QM opens alot of logically possible doors, but it's up to the interpreter to decide what's probable or at least reasonable.

I've enjoyed reading Stapp's papers over the years, but I don't think it's a reasonable interpretation to think a measurement event can have an exclusively physical or mental trigger as he argues there.

Allen said...

I don't agree with Dennett on much, but I do agree with him to the extent that if determinism doesn't allow for free will, then neither does indeterminism.

Probabilistic rules increase the range of states that can potentially be reached from a given initial state...but that's all they add. Instead of one specific outcome per initial state, you have a range of outcomes, each with a probability dictated by the details of the governing rules.

If I roll a truly random dice, and it comes up 6...what explains that? Well, the fact that a dice only has 6 sides is part of the explanation...so "7" wasn't an option. Also, having the dice turn into a bird and fly away wasn't an option. And having it continue to roll for eternity wasn't an option either. The rules of thrown dice dictated that I'd get either a 1, 2, 3, 4, 5, or a 6. To the extent that the outcome wasn't determined by those rules, it's random...there is no reason for it.

So, to the extent that an event isn't governed by a law, then it's irreducibly random. But there's no freedom in randomness either.

I'll go further and say that if reductionist laws don't allow for free will, then neither will emergent laws.

If something happens according to a rule (or law), then it isn't free...it's occurrence is necessitated by the rule. And to the extent that it's not necessitated, then it's random...what else could it be?

Steve said...

Hi Allen:

We talked about this before, but classical indeterminism is not the same as the quantum variety. The latter kind is irreducibly relative to a point of view, and the actualization of the event cannot be interpreted from a frequentist perspective. This is why it can't be described as a product of a stochastic law.

What else could it be? It could be called random, but that is what we usually call the outcome of a classical probability distribution. It can also accurately be called spontaneous or free (albeit constrained by prior and adjacent events).

Allen said...

But how is "spontaneous" different from random, and how does either amount to "free will"?

Either there is a reason for what I choose to do, or there isn't.

If there is a reason, then the reason determined the choice. No free will.

If there is no reason, then the choice was random. No free will.

I don't see a third option.

===

As for quantum randomness, that the probabilities are relative to a point of view doesn't change the fact that they are described accurately using a quantum mechanical framework.

There are regularities, and if the regularities are to be explained they must be explained by reference to some set of rules or laws. Right?

If not, then what form will the explanation take?

So - I still don't see what you're getting at, but I'm interested, if you can clarify.

Steve said...

Either there is a reason for what I choose to do, or there isn't.

If there is a reason, then the reason determined the choice. No free will.

If there is no reason, then the choice was random. No free will.

I don't see a third option.


After dinner I have choice between cake and pie for dessert. I like them both equally. The reasons I have for liking them are equivalently strong. I freely choose pie. This macro-choice at that point turns out scientifically to be constituted by (not "caused by") a collapse of superposed states somewhere in my brain.

If you and I disagree as to whether this is worthy of being called "free will", then I think we might be getting into semantics.

For a more rigorous version along these lines I might recommend the recent book by Mark Balaguer which I posted on: http://guidetoreality.blogspot.com/search/label/Balaguer

PS: yes quantum mechanics has rules which constrain outcomes. But I think the indeterminism can underwrite something worth calling freedom.

Steve said...

Another thought on random vs. free:

What feels free in the first person may seem random to the third person observer. It might be necessary to believe in the non-reducibility of the first-person perspective to consider events free.

Also, it was interesting to me that Conway and Kochen, in their "Free Will Theorem" paper, established that it follows from QM that the application of the term "free" (if it makes sense at all) means the same thing in the context of a quantum particle choosing an outcome and a physicist choosing an experimental set-up. So whatever you want to call one, you should call the other.
http://guidetoreality.blogspot.com/2006/05/free-will-all-way-down.html

Allen said...

After dinner I have choice between cake and pie for dessert. I like them both equally. The reasons I have for liking them are equivalently strong. I freely choose pie. This macro-choice at that point turns out scientifically to be constituted by (not "caused by") a collapse of superposed states somewhere in my brain.

So if there is no reason that the superposed system collapsed into a "pie" state instead of a "cake" state, then the result was random...not free. How could something like this form the basis of free will and ultimate moral responsibility? I don't see it...?

Have you read any of Galen Strawson's work on free will?

I'm familiar with Dennett's position, which I think basically boils to just redefining a bunch of terms and then falsely claiming that the result is what people meant by "free will" all along.

Which is basically like unilaterally changing the definition of "unicorn" to mean "a horse with a horn glued to it's forehead" and then displaying such an animal and thereby claiming, "Unicorn's exist!"

There is no such thing as free will, but people have something definite in mind when they use the term...and what they have in mind is *not* what Dennett proposes.

I agree with the critics of compatibilism in this passage:

"Critics of compatibilism often focus on the definition of free will: Incompatibilists may agree that the compatibilists are showing something to be compatible with determinism, but they think that something ought not to be called 'free will'.

Compatibilists are sometimes accused (by Incompatibilists) of actually being Hard Determinists who are motivated by a lack of a coherent, consonant moral belief system.

Compatibilists are sometimes called 'soft determinists' pejoratively (William James's term). James accused them of creating a 'quagmire of evasion' by stealing the name of freedom to mask their underlying determinism. Immanuel Kant called it a 'wretched subterfuge' and 'word jugglery.'"

====

If you and I disagree as to whether this is worthy of being called "free will", then I think we might be getting into semantics.

I definitely, unambiguously, and wholeheartedly reject what you describe above as being worthy of the term "free will".

Based on discussions I've had with people over the years, I think this is what most people's conception of free will amounts to:

"The ability to make choices that are neither random nor caused."

Obviously there is no such ability, since "random" and "caused" exhaust the possibilities.

But some people believe in the existence of such an ability anyway.

Why? Well...either there's a reason that they do, or there isn't...

Allen said...

"What feels free in the first person may seem random to the third person observer. It might be necessary to believe in the non-reducibility of the first-person perspective to consider events free."

So the feeling of free choice certainly exists. But this is neither here nor there, and I don't accept it as evidence of anything except the existence of consciousness experience.

If something looks like randomness to a third-person observer, then why not just call it randomness???

If an event can't be reduced and explained in terms of lower level processes or prior events, and thus has no obvious cause...that sounds like irreducible randomness to me. It certainly doesn't sound like free will.

So what is your definition of "free will"?

===

"Also, it was interesting to me that Conway and Kochen, in their "Free Will Theorem" paper, established that it follows from QM that the application of the term "free" (if it makes sense at all) means the same thing in the context of a quantum particle choosing an outcome and a physicist choosing an experimental set-up. So whatever you want to call one, you should call the other."

Well, I'll go along with that. I wouldn't call either one free. Rather, I'd say that either *both* are caused by the universe's initial conditions and causal laws (which may have a probabilistic aspect) - OR both are entirely uncaused (a la Meillassoux and his principle of unreason).

It seems to me that you're starting with the belief that free will *must* exist, and then going looking for ways to justify that belief.

You're not arriving at the existence of free will as the logical consequence of any chain of reasoning.

Which seems very suspicious to me.

====

Also, from your comments on the free will paper:

They don't see how science could be taken seriously if its practitioners weren't free to investigate nature by choosing what experiments to perform.

I think this is an excellent, excellent, excellent point - which I've made many times myself. For example: here, here, here, here, here, and here.

Steve said...

Allen: thanks for your comments. I hate to get into semantic debates. And as you point out "free will" debates are plagued with them. And I’m not trying to say anything at all about moral responsibility.

So I shouldn’t really defend the use of the term "free will" because the common conception of it has lots of problems

But I still think we have some degrees of freedom which result from what we're made from.

I definitely disagree with your saying that "random" (in the sense of haphazard) and "caused" (in the deterministic sense) exhaust the possibilities. I’m not sure why you say that. An uncaused but directed free choice is a natural third option. I know it seems classically “unphysical”, but as a non-physicalist that wouldn’t bother you.

I think the measurement event is at the root of experience and intentionality as well as action. It is uncaused, but it is a directed choice. When you put enough of them together in the right way, they create us.

integralscience said...

Steve and Allen:

Interesting discussion! Here is something to consider that may be relevant:

Suppose that every night there is a probability of 50% that I'll choose cake for dessert and a probability of 50% that I'll choose pie. Because the actual outcome is not determined, it appears I am free to choose either one. But if that is true, then I am free to decide to always choose cake. Then I would be not only be selecting an actual outcome, but also altering the probabilities predicted by QM from 50% and 50% to 100% and 0%.

It seems from this that free will implies a violation of QM laws.

Comments?

Regards,
Tom

Steve said...

Hi Tom: that's a good question.

Based on some things I have read I don't think that's a violation per se. It's been argued that a frequentist interpretation of quantum probabiilty doesn't work, in which case any finite string of cakes doesn't formally demonstrate a violation- http://guidetoreality.blogspot.com/2006/06/interpreting-quantum-probability.html

Also, you have the idea that in a complex system you can't precisely repeat the same experiment anyway.

Finally, you have weird phenomena like the quantum zeno effect, where repeated trials seem to change the probability of an outcome.

So, I'm not sure it's incompatible with the rules.

Allen said...

I definitely disagree with your saying that "random" (in the sense of haphazard) and "caused" (in the deterministic sense) exhaust the possibilities.

I use random in two senses:

1) Without definite pattern, order, direction, rule, process, or method. Haphazard.

2) Relating to, having, or being elements or events with definite probability of occurrence.

So when I use random in the first sense, I basically mean "uncaused".

But I also use random in the second sense when referring to probabilistic laws, which I consider a kind of "cause". More on that here (which I think I've mentioned before).

I'm not sure why you say that.

Because "caused" and "not caused" don't seem to leave any room for anything else, due to the law of the excluded middle. See my definition of "cause" below.

An uncaused but directed free choice is a natural third option.

Uncaused. Directed. Free. Choice.

Okay, let's make sure we're on the same page as to what those terms mean.

===

"Uncaused" - this one I think I understand.

Cause: That which in any way gives existence to, or contributes towards the existence of, any thing; which produces a result; to which the origin of any thing is to be ascribed.

Therefore...

Uncaused: That which has no cause. Nothing gave it existence or contributed to it's existence; it is not a result of anything else; there is nothing to which it's origin can be ascribed.

===

"Directed" - This one I'm fuzzy on. Directed in what sense? From where does the direction come? What explains being directed in one way rather than being directed in a different way?

===

"Free" - Free from what? Is this the same as uncaused? If it's different, how is it different?

===

"Choice" - This one is sort of tricky too. To choose is to select among alternatives. But why is one alternative chosen over another? If you choose A instead of B, *why* did you choose A instead of B?

You said that the choice is uncaused and free. But still directed.

However, to me, "directed" sounds a lot like "caused"...?

===

I know it seems classically "unphysical", but as a non-physicalist that wouldn't bother you.

Right. I'm still in the accidentalist/idealist camp. Just trying to get a better understanding of what your position is.

Allen said...

Tom, interesting comment. I'm out of time tonight, but I'll respond asap!

integralscience said...

Steve:

If there were 100 choices of cake in a row, and a predicted probability of 50/50, it seems this would be considered by most as a violation of the prediction, even though it is not strictly speaking impossible.

As for quantum zeno, this has to do with repeated measurements made in such quick succession that it don't allow the system to evolve in between them. I'm not sure how that would apply to this example.

A person is indeed a complex system that in practice could not be prepared in exactly the same way every day, so precisely repeating the same experiment every evening would be impossible. But in that case, without exact preparation, how could one even distinguish between a result of free will and a result that is simply randomly selected by God's dice, as it were?

-Tom

Steve said...

Tom –Clearly you’re right that if a photon went through the right slit 100 times in double slit set-up, we’d think something is fishy. In the complex case of the human brain/body system I think there’s room to work within the rules. But maybe it’s a silly example.

Tom/Allen: With regard to “free” vs. “random”.

I guess I can be accused of anthropomorphizing the quantum measurement event in calling it free. But let me make a couple of comments.

First as we discussed, Conway and Kochen show (and I think the idea goes back to Bohr) the “freedom” of the experimenter is linked in a precise way to the “freedom” of the collapsing particle. (So perhaps there is some excuse for the anthropomorphizing).

But there may also be a more precise way to distinguish the quantum case from the classically random case: the resolving of the indeterminacy via collapse is different from classical indeterminism in that it adds information to the universe.
Here’s a passage where C and K discuss the fact that freedom means not utilizing any information available to the system:

We are left with the case in which some of the information used (by a, say) is spontaneous, that is to say, is itself not determined by any earlier information whatever. Then there will be a time t0 after x, y, z are chosen with the property that for each time t < t0 no such bit is available, but for every t > t0 some such bit is available.

But in this case the universe has taken a free decision at time t0, because the information about it after t0 is, by definition, not a function of the information
available before t0! So if a’s response really depends on any such spontaneous information-bit, it is not a function of the triple x, y, z and the state of the universe before the choice of that triple


Here, when discussing why they think GRW-collapse models can’t work, they distinguish the quantum case from the classically stochastic:

To see why, let the stochastic element in a putatively relativistic GRW theory be a sequence of random numbers …
It is true that particles respond in a stochastic way. But this stochasticity of response cannot be explained by putting a stochastic element into any reduction mechanism that determines their behavior, because this behavior is
not in fact determined by any information (even stochastic information!) in their past light cones.


I'll think about this aspect some more.

Allen said...

Gerard 't Hooft's thoughts on the "free will axiom" as it relates to quantum mechanics.

Steve said...

Gerard 't Hooft is about the only prominent hidden variable determinist interpreter of QM left. He eminently deserves careful attention, but I suspect it's a losing battle.