Monday 26 March 2018

Roger Penrose on Brain & Mind: From the Quantum Scale to the Large Scale (1)




i) Introduction
ii) The Quantum Scale and the Large Scale
iii) The Brain and Quantum Gravity
iv) Daniel Dennett's Quantum Car
v) Microtubules

Throughout Roger Penrose's writings on the brain, consciousness, physics and cosmology, the issue of the link between the quantum scale and the large (“classical”) scale is constantly broached. Indeed all this strongly links in with Penrose's attempt to tie general relativity/gravity and quantum mechanics together.

Penrose's own individualistic position on the relation between the quantum scale and the large scale is expressed in the following:

I am not concerned so much with the effects that quantum mechanics might have on our theory (Einstein’s general relativity) of the structure of space-time, but with the reverse: namely the effects that Einstein’s space-time theory might have on the very structure of quantum mechanics.”

This is (as Penrose himself puts it) “an unconventional view-point” - or it was in 1990!. It's

unconventional that general relativity should have any influence at all on the structure of quantum mechanics!”.

More basically, Penrose believes that “the problems within quantum theory itself are of a fundamental character”.

In terms of the brain and mind, Penrose concluded – again, 28 years ago - by saying that

any putative quantum gravity theory would surely be very remote from the phenomena governing the behaviour of brains”.

Nonetheless, the following is the crux of Penrose's current position:

i) Quantum gravity (or the “structure of space-time”) may have an impact on quantum mechanics.
ii) Therefore quantum gravity may affect the nature of the brain and mind.

At the most basic level, gravitation and general relativity aren't integrated into quantum theory. That alone makes Penrose's views on the brain, mind and consciousness speculative. 

In terms of the brain and mind/consciousness, most neuroscientists and many philosophers believe that quantum phenomena (or quantum events/effects/conditions/etc.) have very little affect on the brain and therefore on the mind/consciousness as a whole. Or, at the very least, that the differences they do make don't really make a difference.

The Quantum Scale & the Large Scale

As stated above, Penrose notes the micro-macro situation in ways which don't directly relate to the brain and mind. In the following, for example, he notes the contextual (i.e., micro or macro) nature of the notion of randomness (or probabilities). That is, Penrose notes how randomness is a consequence of scientists observing quantum effects/events/conditions/etc. at the “classical level”. In Penrose's own words:

Since randomness comes in, quantum theory is called probabilistic. But randomness only comes in when you go from the quantum to the classical level. If you stay down at the quantum level, there's no randomness. It's only when you magnify something up, and you do what people call 'make a measurement'. This consists of taking a small-scale quantum effect and magnifying it out to a level where you can see it. It's only in that process of magnification that probabilities come in.”

This can be deemed to be an epistemic problem, rather than an ontological one. That is, the probabilities (or randomness) arises not from the ontology of the quantum world, but from our epistemic access to it. (This conclusion, at least as it partly applies to quantum indeterminism, dates back to Albert Einstein and was elaborated upon by such people as David Bohm.)

The other point that's worth making about Penrose's position (as quoted above) is that it goes against the stress on quantum indeterminism as it's often used in reference to the brain and mind/consciousness. In other words, Penrose (at least in this context) is de-stressing the random (or indeterministic) nature of the quantum realm; whereas many others (at least in the debate about mind) play it up. (“Quantum indeterminism” is particularly stressed as one explanation of free will.) Of course it must be said here that the words “random” and “indeterminate” (or “randomness” and “indeterminacy”) aren't exactly synonyms. Nonetheless, in the debate about the “quantum mind” (as it's often put), these words are indeed often treated as synonyms (or, at the very least, as near-synonyms).

If we now return to the quantum scale and the large scale.

On a much broader level we can also take Brian Greene's (a Professor of Physics and Mathematics at Columbia University) general point about this micro-macro distinction:

It's not as though the universe comes equipped with a line in the sand separating things that are properly described by quantum mechanics from things properly described by general relativity. Dividing the universe into two separate realms seems both artificial and clumsy.”

This position seems to back up Penrose's previous points about how different levels of description (which are brought about by the effect of “measurement”/observation) determine Greene's “line in the sand” between the quantum realm and the “classical” realm.

And, yet again, Penrose notes these different levels when he talks about Newtonian mechanics, relativity and quantum theory. He stresses the compatibility of these different levels of description/application and their respective “limits”. He says:

Current physics ideas will survive as limiting behavior, in the same sense that Newtonian mechanics survives relativity. Relativity modifies Newtonian mechanics, but it doesn't really supplant it. Newtonian mechanics is still there as a limit. In the same sense, quantum theory, as we now use it, and classical physics, which includes Einstein's general theory, are limits of some theory we don't yet have.”

In the above we can see that rather than measurement (or observation) splitting the universe into two realms, Penrose stresses the respective “limits” of these realms instead.

The Brain & Quantum Gravity

Roger Penrose was - and still is - deeply aware of the arguments against his central position on the brain and mind/consciousness. Indeed when he wrote The Emperor's New Mind (in 1990) he didn't have an original position on the quantum nature of the brain. Specifically, microtubules aren't mentioned in this well-known book. And even neurons and neurotransmitters only get four mentions.

This is what Penrose also had to say (in the same book) on the opposition's position on the brain, quantum mechanics and consciousness:

... they would argue that on a scale relevant to our brains the physical effects of any quantum gravity must be totally insignificant! They would say (very reasonably) that although such physical effects might indeed be important at the absurdly tiny distance scale known as the Planck length — which is 10 35 m, some 100000000000000000000 times smaller than the size of the tiniest subatomic particle — these effects should have no direct relevance whatever to phenomena at the far far larger ‘ordinary’ scales of, say, down only to 10 12 m, where the chemical or electrical processes that are important to brain activity hold sway.”

In fact Penrose went further by saying that his detractors would claim that not even ordinary gravity (as it were) can affect the brain. He wrote:

Indeed, even classical (i.e. non-quantum) gravity has almost no influence on these electrical and chemical activities.”

Penrose concluded with the following sceptical words. (At least as he then believed that they'd be expressed by his opponents.) He wrote:

If classical gravity is of no consequence, then how on earth could any tiny ‘quantum correction’ to the classical theory make any difference at all? Moreover, since deviations from quantum theory have never been observed, it would seem to be even more unreasonable to imagine that any tiny putative deviation from standard quantum theory could have any conceivable role to play in mental phenomena!”

Thus, at this period in Penrose's career (in the early 1990s), his position squared perfectly well with Murray Gell-Mann's later position when Gell-Mann wrote:

... what characterises [Roger Penrose's] proposal... is the notion that consciousness is somehow connected with quantum gravity – that is to say, the incorporation of Einsteinian general-relativistic gravitation into quantum field theory. I can see absolutely no reason for imagining such a thing.”

And all this brings us to Dennett's quantum car.

Daniel Dennett's Quantum Car

Daniel Dennett put this micro-macro quandary very well. He argues (to paraphrase):

Sure, there are quantum happenings in the brain or neurons. Then again, there are quantum happenings in your car, watch and computer.


Most biologists think that quantum effects all just cancel out in the brain, that there's no reason to think they're harnessed in any way. Of course they're there; quantum effects are there in your car, your watch, and your computer. But most things – most macroscopic objects – are, as it were, oblivious to quantum effects. They don't amplify them; they don't hinge on them. Roger thinks that the brain somehow exploits quantum effects...”

We will now need to know why “quantum effects” don't transfer – or apply - to the brain as a whole. Or, more specifically, we need to know why they don't cause (or help bring about) mental phenomena or consciousness. That is, why is there such a sharp dividing line between the micro (Dennett's “quantum effects”) and the macro (the brain or mind/consciousness)? Surely there can't be such a neat and tiny cutoff point between these two worlds. (Then again, it's not logically absurd to argue that there is indeed such a cutoff point.)

It's true that in order for Dennett's watch/car to be a watch/car, it doesn't depend on the quantum effects which are occurring inside it. However, why should that also be true of the brain and its relation to mind/consciousness? The nature and functioning of a car/watch is very different to the reality and functioning of the brain and mind/consciousness. A car/watch is oblivious to the quantum effects inside – though only if it isn't treated qua car/watch! However, it's of course the case that a car/watch can also be analysed as a medium of quantum effects (though not, again, qua car/watch). Then again, it is strictly true that a car/watch - qua car/watch! - doesn't depend on quantum effects/events/conditions? Surely it does so in the simple sense that if there were no quantum effects/events/conditions, then there would be no car/watch either. And, yes, it's true that this applies to literally all other natural objects - and artificial objects as well.

Despite all that, according to Penrose, quantum effects/events/conditions do indeed have an effect on the large scale. He makes that plain here:

The very existence of solid bodies, the strengths and physical properties of materials, the nature of chemistry, the colours of substances, the phenomena of freezing and boiling, the reliability of inheritance — these, and many other familiar properties, require the quantum theory for their explanations.”

However, even though it's true that these “solid bodies”, etc. may “require the quantum theory for their explanations”; that doesn't also automatically mean that such quantum effects are in any way substantive. It simply means that quantum mechanics is a part of the whole picture. So, in the sense of supplying a complete picture of such “bodies” and “materials” - then, yes, of course quantum theory will be required.

Ironically enough, Dennett himself does accept that quantum events/effects/conditions/etc. influence (or affect) the large scale. He says that quantum mechanics is

stunningly successful at predicting and explaining many phenomena, including everyday phenomena such as the reflection and refraction of lights, and the operation of the proteins in our retinas that permit us to see”.

Of course it may still be the case that because

quantum mechanics can “predict and explain” (remember that Penrose also used the word “explanation”) such things as “the reflection and refraction of lights”

that this doesn't also mean that

quantum mechanics has an (causal) impact on these things.

.... Then again, surely it does mean that! 

And if all this is true of the aforementioned light and protein molecules, then why can it also be true of the brain and consciousness? Of course the parallels between

quantum mechanics and the reflection and refraction of light

and

quantum mechanics and the brain and mind/consciousness

may not be parallel (or equivalent) in every respect. However, surely that wouldn't matter too much in this case. What matters is whether or not quantum mechanics is having an impact on the brain and therefore on the mind/consciousness. It doesn't need to be the case that quantum mechanics does so in precisely the same way in which it impacts on (to use Penrose's words again)

solid bodies, the strengths and physical properties of materials, the nature of chemistry, the colours of substances, the phenomena of freezing and boiling, the reliability of inheritance”.

To repeat: perhaps the quantum-mechanical explanations of these phenomena are at a different level to actually arguing that quantum-mechanical events actually bring about (or cause) such phenomena. Again, is there a difference between 

quantum mechanics explaining consciousness 

and 

quantum-mechanical effects/events/states causing (or bringing about) consciousness? 

Surely if quantum mechanics can explain the mind/consciousness, it can only do so because quantum-mechanical events/effects/conditions also bring about (or cause) the mind/consciousness.

Microtubules

Having said all that, it's of course the case that Penrose is fully aware of the need to explain this micro-macro link. The following is just one example of him doing so:

For my picture, I need this quantum-level activity in the microtubules; the activity has to be a large-scale thing that goes not just from one microtubule to the next but from one nerve cell to the next, across large areas of the brain. We need some kind of coherent activity of a quantum nature which is weakly coupled to the computational activity that Hameroff argues is taking place along the microtubules.”

So Penrose acknowledges the need to tie the quantum scale to the (to use Penrose's own term) “large-scale”. Basically (as with Dennett's car/watch), there are indeed quantum effects/events/conditions in microtubules – as there are everywhere else. So how can we tie these microtubular quantum phenomena to the large-scale? That is, how can we tie them to nerves and indeed from “one nerve cell to the next, across larges areas of that brain”? In a sense, if quantum effects/events/conditions are happening at the level of microtubules, then (as stated) they must also be happening at the level of nerve cells and indeed across large areas of the brain. But, again, are these nerve cells or large areas of the brain in the same position as Dennett's car/watch? (The one obvious difference is that the former are biological and the latter aren't.)

In the quote above (at the least), Penrose doesn't offer us an answer to these questions. The questions are simply raised. Indeed to use Penrose's own words:

We need some kind of coherent activity of a quantum nature which is weakly coupled to the computational activity that [Stuart] Hameroff argues is taking place along the microtubules”.

In basic terms, the quantum effects/events/conditions which occur in individual microtubules need to be “coupled” with the quantum effects in other microtubules. This coupling, according to Penrose, is achieved through “quantum coherence” and “quantum superpositioning”. Clearly these ideas take us beyond neuroscience.

So isn't all this mere speculation?

Whatever the case is, Penrose's positions will require both quantum theory and neurobiological detail to stand their ground. That is, the quantum leap from the neurobiological quantum scale to the brain and mind/consciousness needs much quantum-theoretic, neurobiological and philosophical defence.

*) To Follow: 'Roger Penrose on the Brain & Mind: Microtubules' (2)


Wednesday 21 March 2018

Paul Austin Murphy: Facebook Philosophy Debates (3)


   Evolutionary Theory, the Big Bang and Tests




        The Constants & the Laws of Nature



              "Reductionism" is a Dirty Word


             Determinism & Predictability



                 Eternal Physical Laws?



Friday 16 March 2018

Paul Austin Murphy: Facebook Philosophy Debates (2)



               Human Beings and Computers



                       Science and Proof


               Communication and Grammar



        The Laws of Physics and Universality


Paul Austin Murphy: Facebook Philosophy Debates (1)



                              Logic and the Constants of Nature




              Hameroff, the Afterlife & Panpsychism




                               Francis Crick and Reductionism






Friday 9 March 2018

Francis Crick's Deliberately Provocative Reductionism




i) Introduction
ii) Only Dependent on the Brain?
iii) Where in the Brain is an Ambition?
iv) Conclusion


In Francis Crick's 1994 book, The Astonishing Hypothesis: The Scientific Search for the Soul, he wrote the following oft-quoted passage:

'You', your joys and your sorrows, your memories and your ambitions, your sense of personal identity and free will, are in fact no more than the behavior of a vast assembly of nerve cells and their associated molecules.”

It's easy to believe that Francis Crick was being willfully provocative and rhetorical here. At the same time, he may also have been telling the truth – if only to a degree (as shall hopefully be shown).

In terms of the rhetoric and provocation, it's true that Crick's critical attitude towards religion was one motivation for writing The Astonishing Hypothesis. So, to put it in non-rhetorical terms, Crick certainly did believe that religions can be wrong about scientific issues (as do many religious people). He also claimed that it is science's job to rectify the false claims of these religions. (Or at least those claims which appear to have a scientific subject.)

Crick was also well aware that when he began studying consciousness he was tackling a subject which traditionally had been the sole property of religion and philosophy.

Another point that can be made about Crick's rhetoric and provocation is that he was simply attempting to get a point across. And the best and simplest way of doing that is to be poetic and rhetorical. After all, strongly-expressed views often attract a large audience. Nonetheless, the extremity of a view doesn't automatically mean that it's false  - at least not in every respect. Thus perhaps Crick enticed people in and then gave them a broader and more nuanced perspective on his extreme words (i.e., those quoted above). Though it's of course possible that this is to give Francis Crick the benefit of the doubt.

Despite the opening quote, Crick does express the same idea in a slightly less provocative (i.e., more technical) way. That is, he also wrote:

"A person's mental activities are entirely due to the behavior of nerve cells, glial cells, and the atoms, ions, and molecules that make them up and influence them.”

So is that any better?

As already hinted at, the prefix “seemingly” (as in “seemingly extreme”) is used because what Francis Crick says isn't really extreme at all. It's partly true (if, as stated, in a limited way) – at least in becomes truer when the rhetoric is stripped away and the position is both defended and criticised.

In addition, the very fact that Francis Crick decided to study consciousness in the first place may – or does – suggest that he couldn't have been a reductionist in any strict (or traditional) sense. After all, in much psychology, neuroscience/neurobiology and sometimes even in philosophy, consciousness had been reduced to brain/behavior or simply ignored. Then again, most of The Astonishing Hypothesis is about neurobiology. Thus, even though the opening quotation is in essence a philosophical position, the philosophical defence and implications of that passage are rarely fully developed in the book itself.

Only Dependent on the Brain? 

Let's put the central position in this very simple way.

If it weren't for the brain (or if it weren't for the “nerve cells” mentioned by Francis Crick), then it's indeed the case that we wouldn't have (to use Crick's own words) “memories, ambitions, personal identity, free will, sorrows”. All these things do depend on the brain. Isn't that blatantly obvious to most (though, of course, not all) people?

Now does it follow from this that joys, sorrows, memories, ambitions, personal identity and free will (taken individually) are identical to a group of neurons, a part of the brain, or even the entire brain taken “holistically”? Not really.

Indeed how can one thing actually be another thing? Or in terms of Leibniz's Law:

If x and y are identical, then everything true of x must also be true of y.

Is a group of neurons identical to your memory (to take just one example) of a cat drowning in a river in 2010? In Leibnizian terms again:

i) If your memory of a cat drowning in 2010 is identical to neuron set x (which is its “subvenience base”),
ii) then everything true of that memory (taken as a mental phenomenon) is also true of neuron set x.

Yet surely that can't be the case. 

It is true that the memory (as a mental event/state) itself is about a cat's death in a river. Is neuron set x also about a cat drowning in a river? The memory itself relates to something which occurred in 2010. Does neuron set x also relate to an event in 2010 - at least in the same way as the (mental) memory does? Inversely, brain part x is grey-pink, fleshy and three-dimensional. Is the memory of a dying cat also grey-pink, fleshy and three-dimensional? And so on.

Nonetheless, it's certainly the case that the memory of a cat drowning in 2010 may be “encoded” (let's ignore the precise meaning of that word) in a part of the brain or even (somehow) in much of it. However, is the memory itself simply and purely a part of the brain?

The memory itself has some kind of relation to a past event which was evidently outside the brain. And even if we can say that a part of the brain itself (rather than the the mental content of the memory itself) also has a relation to something outside of it, it still can't be identical to what's outside of it – by definition

To repeat: although the memory is indeed dependent on a part of the brain, it can't be identical to it. To paraphrase Leibniz again:

There are things true of the memory of a dying cat that aren't true of the part of the brain which is its material subvenience base. (Let's ignore “externalist” or “broad content” arguments for now.)

One other such truth is the subvenience base of the memory is material – it's made out of neurons, glial cells, atoms, axons, dendrites, molecules, myelin, charged particles, electrical currents, neurotransmitters, etc. Surely the mental memory of a dying cat isn't made out of any of these things.

The Francis Crick quote is problematic in another way too.

Crick seems to be referring exclusively to the brain or to its “nerves cells”. However, joys, sorrows, memories, ambitions, personal identity, etc. also have physiological or bodily aspects which go beyond the brain. Being sorrowful, for example, can make you physically lethargic and even ill. It's true that these physiological or bodily effects are also related to the brain and therefore to Crick's nerve cells. However, like memories, etc., they aren't identical to them. Then again, there are nerve cells (e.g., motor, sensory and autonomic) throughout the body. That is, when you're tired (in the sense that your body becomes weaker, you become sleepy, etc.), even these physiological events/conditions outside the brain are related to neurons in the brain. (Such nerve cells outside the brain are sometimes classed as “projections of neurons”.) Then again, it's still the case that not all nerve cells are neurons.

Where in the Brain is an Ambition?

In the case of certain other examples cited by Francis Crick, it's hard to even conceive of what he means.

Francis Crick mentions “ambitions”. 

More accurately, take the case of a particular ambition of a particular person at a particular point in time.

The idea that a particular ambition is identical to a particular set of nerve cells (or a particular part of the brain) seems very odd. What could it mean?

Let's use Mr X's ambition to want to rule the universe as an example. 

Could that really be fully accounted for by the brain alone (or by a set of neurons)? If it were, then perhaps a neuroscientist could look at that set of neurons and literally either see the ambition or get to knows its content in some other way.

However, let's say that in principle an ambition (or another psychological attitude) is caused/brought about/etc. by a particular part of the brain which can be fully and successfully observed and investigated by magnetic resonance imaging (MRI), elctroencephalography (EEG), or by positron emission tomography (i.e., a “PET scan”). The neuroscientist still wouldn't observe - or get to know the content of - Mr X's ambition to want to rule the world. The only way he could know about the Mr X's ambition would be to ask him.

And even if a precise correlation between this ambition and a part of the brain existed, the neuroscientist would still need to question Mr X about it. 

Conclusion

So Francis Crick may well be confusing the fact that brain parts physically cause, bring about, or physically instantiate (as it were) memories, attitudes, etc. and even that such things can be strongly correlated (at least in principle) with brain parts. However, brain parts (or sets of nerve cells) aren't themselves memories, attitudes, etc. The two things are very different. 

(It's a little like the difference between the cause of a fire and the fire itself. A struck match was a necessary - though not sufficient - cause of a particular forest fire. However, the striking of the match  - or the lit match itself - and the forest fire were very different things.)

Again, the brain's parts are necessary for memories, sorrows, etc; though they aren't identical to - or sufficient for - them. That means that Crick's phrase “are in fact no more” is (strictly speaking) false.

Nonetheless, none of this extra detail (as it were) needs be non-natural, non-physical or “spiritual” in nature. That extra something will include mental states/events, other parts of the body (as well as bodily physiology), the external environment, personal and communal history, language, culture and many other things – all of which are indeed either physical/natural or abstractions from the physical/natural.