A Critical Review of Thomas Nagel’s latest book Mind and Cosmos

MindandCosmoscoverThomas Nagel’s book Mind and Cosmos has garnered a lot of attention since its publication, with the reaction being intense, heated, and of largely mixed opinion (For a nice overview and response to negative views, see here). Not surprisingly, those sympathetic to naturalism have been harsh in their assessment, and those not so sympathetic have been full of praise. My assessment is ultimately negative, but I think both the defenders and critics of Nagel’s book have relied on a set of shared assumptions that are deeply problematic and masked by ambiguity. By exposing the hidden assumptions framing the debate between “reductionism” and “non-reductionism”, I show that Nagel’s criticism of “reductionism” is sound, but this is no reason to reject physicalism, only an outdated and confused version of physicalism.

1. The Problem of Hierarchy: Two Views of Reduction

The controversial subtitle of Mind and Cosmos is “Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False”. Quite the claim! But what exactly is “Materialist Neo-Darwinism” and who really holds this view? More precisely, Nagel’s target for criticism is what he calls:

“A particular naturalistic Weltanshauung that postulates a hierarchical relation among the subjects of those sciences.”

I have a lot to say about this notion of a “hiearchical relation”, so bear with me! I propose Nagel’s invocation of a “hierarchy” is ambiguous between two senses of the term. First, there is a hierarchy of scale that is compositional e.g. Society is composed of individuals, which are composed of cells, which are composed of molecules, which are composed of atoms, etc. I take compositional hierarchy to be non-controversial.

The second sense of “hierarchy” is what John Heil calls a “hierarchy of being” or “hierarchy of reality”. On this view, you have lower-level “realizer bases” out of which higher-order properties “emerge”, in the sense of “strong” emergence where the whole is non-compositionally greater than the sum of the parts (whatever that means). For example, on the hierarchical view of reality, the mind “emerges”, “arises”, or is “generated” as a higher-order property “out of” the lower realizer bases, and is said to “supervene” on that lower base. Nagel is perfectly right to think this is a mysterious process, but that’s a good reason for physicalists to reject the entire hierarchical view of reality, not give up on physicalism.

The alternative picture is that reality is flat. There is one level of reality: it’s called reality! Within that level we can find hierarchies of scale and composition, but ultimately there are not two different levels or types of “being”, one physical and the other mental, with the latter “emerging” or “arising” out of the former. Nagel seems to think that physicalism is committed to this view, but ironically the problems he locates with reductionist physicalism stem from his own dualist intuitions about the existence of “higher” levels of reality. However, an ontologically serious physicalism has no room for different “levels” of reality, and thus it is not a “problem” to try and reduce the mental “level” to the physical “level” because that view of reduction relies on the problematic notion of there being a hierarchy of reality in the first place. In his book From an Ontological Point of View, John Heil recommends that

 …[W]e abandon the notion that reality is hierarchical. We can accept levels of organization, levels of complexity, levels of description, and levels of explanation, without commitment to levels of reality in the sense embraced by many self-proclaimed anti-reductionist philosophers today.The upshot is a conception of the world and our representations of it that is ontologically,but not analytically,reductive.

Agreed! This result generalizes to the entirety of Nagel’s critique of physicalist reductionism. While Nagel is right to argue that reductionism is problematic, the entire problematic of reducing higher levels of reality to lower levels of reality is a product of the dualist worldview, not the physicalist one. It bears repeating that on the physicalist view, there is no problem of “reducing” the mental to the physical because setting the problem up like that buys into the traditional dualist framework of reality as hierarchically layered. In a nutshell, Nagel is criticizing a dualistic view of physicalism, and thus his critique of physicalism says more about how Nagel views the world than it does about how physicalists do.

To be fair, many physicalists have unwittingly bought into the same “levels of being” view that is problematic, but insist that the “reduction” of the highest levels to the lowest is tractable. I agree entirely with Nagel that this project of reduction is doomed to failure, but not for the same reason Nagel does. My problem with the project of reduction is that it sets up the problem wrong, whereas Nagel think it reveals the truth of dualism (or at least the falsity of physicalism).

Nagel claims that his book is

“…[N]ot just about acknowledging the limits of what is actually understood but of trying to recognize what can and cannot in principle be understood by certain existing methods.”

Having cleared up the ambiguity of hierarchies, we can now analyze Nagel’s conclusions about what can and cannot be understood by the physical sciences. If the project is to say it is impossible for the physical sciences to “reduce” the “mental level” to the “physical level” then I agree entirely. But not because I doubt the truth of physicalism. The mental level cannot be reduced to the physical level because the whole idea of there being different levels is a product of the traditional dualist worldview where reality is divided into base terrestrial materials and higher spiritual realms.

Thus, when Nagel criticizes the project of “materialist reductionism,” he kind of has a point, but it’s impossible to see this unless we clear up ambiguities about how physicalists can think about reductionism. I propose there are essentially two types of materialist reductionism: call them Reductionism and Eliminativism. Reductionism is the confused view we have been discussing, where it’s acknowledged at the start there are two levels of being, and the problem is to reduce the mental level to the physical level or provide psycho-physical “bridge laws” between the two levels. In contrast, Eliminativism says all that exists is the physical level. Rather than starting with two levels, Eliminativism starts with one level and all phenomena as well as explanations of phenomena are framed in terms of this level of reality.

As I see it, Nagel is right to criticize Reductionism, but his arguments don’t apply to Eliminativism. Unfortunately, Nagel doesn’t make this distinction clear and doesn’t engage with the alternative one-level view of reality, which is the true competitor to the traditional dualist worldview. I can imagine what Nagel would say if he heard about this distinction. He might say it’s completely counter-intuitive because it denies the reality of “first person subjective experience”. But again, this talk of “denying reality” is ambiguous between denying that psychological phenomena “live” in the higher-realm of a two-level reality or denying that it exists at all. Physicalists don’t have to deny that psychological phenomena exist; they will just say that, whatever they are, they “are” just like everything else: existing in the complex, flat ontology that is our physical universe. Thus, physicalists only deny the reality of mental phenomena if it is assumed that mental phenomena “live” in a higher plane of existence in the two-level picture of reality.

Of course, given the complexity of the universe, physicalists have no expectation that humans will be cognitively comfortable (or even capable) of accounting for everything they want to explain in terms of the lowest compositional scales (atoms, quarks, etc). Rather, we abstract to higher compositional scales to deal with complex phenomena like human civilization. But all this abstraction is abstracted within a single level of reality. The psychological necessity of parsing the world into higher and lower scales is not a metaphysical proof of separate planes of reality. In fact, a physicalist understanding of human cognition would predict that humans would not be capable of handling reams of data without compressing it with language, graphs, equations, simulations, models, etc.

Thus, the following statement by Nagel is actually a prediction of the naturalistic concept of human cognition:

“For a long time I have found the materialist account of how we and our fellow organisms came to exist hard to believe.”

Of course such a massively complicated proposition is “hard to believe”. A lot of things are hard to believe because we are forced to use our puny primate brains to understand a large, scarily complex physical universe with weird things like black holes, quarks, and gravity. Why would we expect it to be easy to imagine abiogenesis? Essentially, Nagel’s argument that not-P is: “I don’t understand P, therefore not-P.” But if P is physicalism, and physicalism predicts that humans will have a hard time understanding complicated things, our lack of understanding (especially of nonscientists) is surely not a refutation of physicalism, merely a recognition of its cognitive complexity.

2. Flubbing the Facts

Ontology aside, I do think Nagel makes some empirical gaffes exposing his ignorance of mainstream biological science, especially when discussing the state-of-the-art materialist conception of abiogenesis. He says, incredibly:

“The more details we learn about the chemical basis of life and the intricacy of the genetic code, the more unbelievable the standard historical account becomes”

If history has taught us anything, believability by non-scientists is not a good metric for the truth of scientific claims. For many non-scientists, Einsten’s theory of relativity is unbelievable, but that obviously has no bearing on its truth. Nagel continues:

“[Abiogenesis] flies in the face of common sense…

“….It is prima facie highly implausible that life as we know it is the result of a sequence of physical accidents together with the mechanism of natural selection

“…When we go back far enough, to the origin of life – of self-replicating systems capable of supporting evolution by natural selection- those actually engaged in research in the subject recognize that they are very far from even formulating a viable explanatory hypothesis of the traditional materialist kind”

It would behoove Nagel to google the phrase “hydrothermal origins of life” to find proposed models of abiogenesis that start from recent discoveries of deep-sea heat vents. A quick search on Wikipedia and you can find the “iron-sulfur world theory” of abiogenesis. There are probably other rival hydrothermal theories, and I have no idea whether any of them are true, but the point is that they seem, to me, like a “viable explanatory hypothesis of the traditional materialist kind”.

Perhaps there is an ambiguity in Nagel’s use of “formulation”. Maybe he means “nobody has formulated a complete explanation established to be almost certainly true”. This would be true, but that’s simply an argument from ignorance. You can’t infer from the fact that we haven’t yet formulated a “complete” explanation that there isn’t a complete explanation.

However, if Nagel means “nobody has even formulated a viable educated guess” about the origins of life, this is almost certainly false, unless he can show why hydrothermal models aren’t “viable” as possible explanations.

3. Good Darwinians vs Bad Darwinians

Another thing that confused me is who Nagel considers to be a “bad Darwinian materialist” and who is a “good” materialist. Right after harshly criticizing Richard Dawkins for explaining the evolution of the eye “merely as a result of chemical accident, without the operation of some other factors determining and restricting the forms of genetic variation”, Nagel gives an example in a footnote of presumably “good”, non-reductionist Darwinians, “who insist that the evidence calls for a more restricted account of the sources of variation in the genetic material.” Surprisingly, Nagel cites Stuart Kauffman has a “good” non-reductionist, saying in that same footnote “Stuart Kauffman suggests in several books that variation is not due to chance, and that principles of spontaneous self-organization play a more important role than natural selection in evolutionary history.”

This is confusing on multiple levels. Is Nagel implying that Kauffman is “on his side” merely because he denies that all variation is due to chance alone and not chance in addition to other factors like the material property of spontaneous self-organization? If big, bad “Darwinian materialism” is supposed to be the claim that chance alone is the full story, then Nagel is making a stink about a view that few biologists actually hold. It might be convenient to treat chance has the primary operator, but this is because dealing with the entire material evolution of cellular matter is absurdly complicated, and would require a ridiculous amount of computing power to simulate.

I can’t speak for Kauffman’s own ontological views, but Kauffman-esque “non-reductionism” is ambiguous between materialist Reductionism and materialist Eliminativism. It’s conceptually possible that all the “spontaneous” self-organization of matter is a property of the single level of reality that is the physical universe. This might be wildly complex, but why shouldn’t it be? It’s the universe itself we’re talking about here, not a toy model of it. But nothing about wild and strange self-organizing properties of matter is inconsistent with materialist Eliminativism. Thus, Nagel’s appeal to Kauffman has a counter-example to reductionism is ineffective as a genuine criticism of the physicalist worldview.

Conclusion

As a card-carrying “Darwinian materialist” who wears his naturalistic credentials proudly, I am sympathetic to the received criticisms of Nagel’s book. However, unlike other naturalists who have criticized Nagel’s book, I think Nagel’s criticism of Reductionism is sound: it is impossible to reduce the mental level to the physical level. Nagel’s critics have mistakenly limited their options to either joining Nagel in attacking Reductionism or accepting Reductionism as formulated by Nagel.

I reject both options in favor of Eliminativism. The reason why it’s impossible to reduce the mental level to the physical level is that this very way of setting up the problem belies the traditional view of reality as composed of “levels of being”, with the mental level “emerging out of” or “arising from” the physical level. For eliminativists, there is a single level: physical reality, and humans exist only on this level. But we certainly don’t talk or write this way. For good reason: we have puny primate brains with finite memory and processing power. It’d be futile to try to understand WWII in terms of Schroedinger’s equation, but this cognitive inability does not entail the falsity of quantum mechanics. Likewise with psychology.

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12 Comments

Filed under Books, Consciousness, Philosophy, Psychology

12 responses to “A Critical Review of Thomas Nagel’s latest book Mind and Cosmos

  1. VicP

    My take Gary as an electrical engineer is that you could reduce the computer to the storage of electrons and timing of electrical circuits at the component level but what we see on our computer screens is still electron states, but the display aspect of the computer has been slowed down to our time domain so we can read it.

    The issue may be that our biology operates in a much slower time domain than the physical levels which science delves. Although light impinges our retina, our internal visual system flicker fuses in the same time domain as our speech and hearing.

    Because our muscles and bodies move around in this physical time domain of reality, our mental matches it.

    Biology has little problem explaining most time domain functions and physical structures in the body from the physical level up. The problem is still how nature goes from the time domain of the physical to the time domain of the mental which leads to Nagel’s philosophical language.

  2. Hi Vic,

    “The problem is still how nature goes from the time domain of the physical to the time domain of the mental which leads to Nagel’s philosophical language.”

    I agree that the limitations of biology lead to Nagelian-type language, but I don’t see why the practical necessity of using certain forms of language describing different “levels” of reality has any metaphysical significance unless we are prepared to “read off” our ontology from our language.

  3. Gary,

    The law of the conservation of energy applies at both the particle level and for a car rolling down the highway and we can work out the mathematics for each. A car is just a more complex collection of particles so the “bridging laws” and intuitive bridge is obvious. I see your point that for the mental and physical both levels should be obvious but there is some psychological block. Well from the psychological perspective there may be certain fundamental functions that cause qualia and other fundamental functions in the neocortex that detect qualia, sort qualia, talk about qualia etc. Scott Bakker thinks the brain is fundamentally blind to understand itself but I say this is just a starting point to saying that we still need to reverse engineer or unravel the brain in a more orderly fashion. Qualia may be a basic function which we share with every species but as you say I doubt the amoeba can taste the sweetness of a sugar molecule. But it’s that big folded umbrella of a neocortex that nature has given which is rooted in that big amoeba we call a body that you and your friends are constantly researching, reading and talking about. Alot of great work has been done on this complex challenge.

    Vic

  4. Han

    Great post! I completely agree with you on the idea of a flat ontology. Are you familiar with Manuel De Landa’s take on Deleuze? In “Intensive Science and Virtual Philosophy” he does a great job of linking this kind of flat conception with your compositional hierarchy idea, using ideas borrowed from the theory of dynamical systems.

    One thing that I find slightly frustrating about philosophers’ engagement with science is the fixation on “truth” as opposed to usefulness. What I mean is that one can also look at the most successful physical sciences — physics and chemistry — in terms of their powers of prediction, and their ability to facilitate controlled, premeditated manipulations of nature. Philosophers sometimes juxtapose truth with believability/plausibility/conceivability, but I think for many people within and outside science, power contributes to both. Ideas are hard to believe until the processes they engender become commonplace in technology. Think of humans flying, or the recording of sounds.

    From the perspective of usefulness, one might say that (so far) the monist/physicalist conception of mind can be taken as true or false without reliably contributing to physical power over the mental. A psychologist or neurologist cannot yet work with these positions to manipulate minds. Or alternatively, they might believe in either without changing anything practical.

    If we expect more from science than true propositions, but in addition physical tools that can convince us that the propositions carry real force (outside of the chattering classes), then we might say that cognitive science is not yet a science at all. In which case declaring its truth or falsehood is premature.

  5. Hey Han,

    Thanks for the comment!

    “Are you familiar with Manuel De Landa’s take on Deleuze? In “Intensive Science and Virtual Philosophy” he does a great job of linking this kind of flat conception with your compositional hierarchy idea, using ideas borrowed from the theory of dynamical systems.”

    Yes, I studied that book a few years ago when I was studying Deleuze with John Protevi at LSU, but in writing this review I had forgotten how close the connection is with Deleuzian metaphysics. But you’re right: they’re very closely related (especially Deleuze’s critique of hylomorphism and his positive replacement of double articulation i.e. “God is a lobster” ).

    “From the perspective of usefulness, one might say that (so far) the monist/physicalist conception of mind can be taken as true or false without reliably contributing to physical power over the mental. ”

    Well said! I agree entirely. Sometimes when I press for these strong monist/physicalist ontologies people accuse me of wanting to “halt” the useful progress of the neuro/cognitive sciences, or to somehow place restrictions on the type of concepts/vocabulary scientists employ in their day-to-day practice, including writing up papers and books.

    However, my aspiration in pressing for these ontologies is, to put it poetically, more religious in nature than it is scientifically useful. That is to say, my goal in pressing for these “austere” ontologies is not to aid the physical sciences (they seem to be doing fine all on their own), but rather, to get the general intelligent reader to think differently about how the manifest image of reality interacts with the scientific image, to provide an alternative metaphysical/cosmological picture for when we contemplate our place in the universe.

  6. Gary-

    When it comes right down to it, I am an elimitavist too. There is only one level. We like to chunk things into “higher level” things like economies, Chevrolets, and World War II because of our cognitive and perceptual limitations, but as the universe clanks along, moment to moment, it only deals with the One True Level as it decides what to do. I have not read Nagel’s book, but the quotes you pulled out were pretty damning, kind of embarrassing. He seems to be begging to be accused of a simple failure of imagination, a failure to grasp the huge scales we are talking about when we describe primordial earth, the size of the oceans, and the hundreds of millions of years evolution had to play with.

    We part ways, however, when it comes to qualitative consciousness, which I think contitutes a counterexample of a certain strict version of naturalism. It does not bother me that we can not define consciousness preciesly – precise defintion usually being the last step, the capstone of the pyramid. There is still only One True Level at which the universe operates, but that level is less neat, less easily characterized (a handful of fundamental particles, behaving in ways described by a handful of laws, couched in terms of a handful of constants) than we might like. Nature, it turns out, is more baroque, even ugly. Our preference for tidy, neat little systems, however, is not binding upon nature.

    I kind of wonder if the eliminativism (which you like) and the reductionism (which you don’t like) are just different ways of talking about the same things. If I say that WWII can be reduced to quantum foam, is my ontology really all that different from someone who says that in a sense there is no separate WWII, just quantum foam? Tomayto/tomahto?

    -John Gregg
    http://www.jrg3.net/mind/

    “Physics is the only real science. The rest are just stamp collecting.”
    -Ernest Rutherford

  7. Hi John,

    Thanks for the comment!

    “I kind of wonder if the eliminativism (which you like) and the reductionism (which you don’t like) are just different ways of talking about the same things. If I say that WWII can be reduced to quantum foam, is my ontology really all that different from someone who says that in a sense there is no separate WWII, just quantum foam? Tomayto/tomahto?”

    In order to answer your question, I think it’s important to distinguish between two types of reduction: ontological reduction and epistemic reduction. The difference between the two is that epistemic reductions must be comprehended by humans at some realistic level.

    With that said, I believe WWII can be ontologically reduced to quantum foam, but not epistemically reduced. We can utter the sentence “WWII is really just quantum foam arranged WWII-wise” and believe this statement is true but no human could really wrap their head around this. Not only would this analysis be too incomprehensible, it wouldn’t be useful for teaching, prediction, manipulation, or understanding.

    So what’s the purpose of giving ontological reduction if we can’t understand it? Good question. What’s the purpose of anything? Suppose I just find ontological reduction philosophically interesting. That’s enough for me.

  8. Thank you for this write up, Gary. This is the first time in a long time that I read a complex and sophisticated analysis and agreed with every single point. Lucid, compelling and (in my opinion) absolutely correct. Well done.

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  12. trehub

    Gary, what are your thoughts about the approach advocated in “A Foundation for the Scientific Study of Consciousness”? The chapter can be seen here:

    https://www.researchgate.net/profile/Arnold_Trehub

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