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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I show that Nagel’s criticism of “reductionism” is sound, but this is no reason to reject physicalism, only an outdated and confused version of physicalism.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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Gilbert Ryle and the Proper Referents of Psychological Vocabulary

When we say “Bob sees a cat” or “I see a cat”, what does the term “see” refer to? If you are of a scientific bent, then you might say that verbs like “see” refer to internal physiological events such as patterns of brain activity. Alternatively, if you are of a psychologistic bent, you might think that the term “see” refers to internal mental events of some kind. Gilbert Ryle thinks both of these positions are mistaken.

Ryle uses the example of winning a race to illustrate his point. Imagine a hard-nosed materialistic scientist who was conducting a study of the physiological processes and cognitive functions intrinsic to a runner’s natural makeup. He studies the runner’s muscle tissues, brain fibers, sweat glands, heart function, etc. in painstaking detail. But now he begins to investigate whether or not that runner has won a race. He puts tissues under the microscope and inspects the entirety of the runner’s intrinsic physiological and psychological makeup but he just cannot find out whether or not the runner has won a race or not.

Ryle thinks that the scientist fails in his investigation of whether the runner has won a race because he is looking in the wrong place and the wrong way. The proper thing to do to tell if the runner has won a race is to investigate into whether the runner recently competed against rivals, did not cheat, and crossed a socially-recognized finish line. Likewise, Ryle thinks that, in determining whether or not Bob has seen the cat, one does not need to open up Bob’s body and brain to discover whether or not seeing has occurred. For Ryle, to look for “seeing” as if it were an internal physiological event or process would be like looking for “winning” by opening up the body and brain of a runner. A big motivation for Ryle’s view is the fact that a person ignorant of the physical details of his or her own brain can clearly still determine whether he or she is successfully seeing a cat. So, Ryle thinks, the verb “see” does not refer to inner physiological processes. Thus, Ryle thinks that seeing is not a process at all, but something else.

Ryle contends that because facts about psychological verbs like “see” are not discovered in the same way as facts are about physiological processes, it is a “mistaken assumption that perceiving is a bodily process” (109). There are at least two ways to read this claim: strong and weak. The strong version is that Ryle is making a bold metaphysical claim about how critters actually perceive the world. On this strong reading, internal bodily processes are just not involved in perceiving at all. This reading is untenable because Ryle probably did not mean to overturn any neurophysiological facts of perception. The weak reading is more plausible. It says that Ryle thought that psychological discourse is of an entirely different sort than physiological discourse. On the weak reading, when Ryle says “Perceiving is not a bodily process”, he means to say that talk about perception is not on par with talk about bodily processes.

In my opinion, the philosophical force of the weaker claim is reduced given the fact that psychological discourse is not fixed or stable or even universal. Given the almost certain possibility that human languages will continue to evolve, what is the philosophical significance of saying that right now the folk psychology of English speakers is different from our scientific psychology? Is this a necessary truth or a contingent historical fact? Following a Sellarsian line, if we could coherently imagine a society of techno-elites growing up with portable brain scanners permanently attached to their skulls and the schooling necessary to effortlessly interpret the scanning analyses displayed on their wrist-computers, then we could imagine a society where the way facts are discovered about the psychological world would essentially be no different from the way facts are discovered in the physical world.

Replicating such technology in the here and now isn’t completely fantastical either; it would only be a matter of sophisticated biofeedback making information available in a format accessible by our brains. However, if you were inclined to accept a higher-order theory of consciousness, then in a way we already have biofeedback of our brains insofar as what makes higher-order thought special is our brain’s way of reacting to itself, of perceiving its own perceptions. There is an analogous point to be made about thinking itself insofar as in some scientific circles it is fashionable to talk about conscious thought as overt speech that has been sufficiently internalized.

It seems then that Ryle’s contention that perceptual verbs do not refer to internal physiological processes and cognitive functions could turn out to be both metaphysically and grammatically incorrect given we specify the relative technological sophistication of the society in question. If we lived in a more scientifically literate society, we could easily imagine (à la Richard Rorty’s Myth of the Antipodeans) psychological verbs referring to internal physiological processes (available to view through portable brain scanners). And if this is true, the philosophical force of Ryle’s argument is diminished, for what else is Ryle doing except pointing out the merely sociological fact that right now our language games about psychology are dissimilar from our language games about physiology? If this is only a contingent fact of history, I take it that, following Sellars, the interesting philosophical point is not that we have such language games, but that the language games are not fixed, and in fact indicate an evolutionary trajectory. Just as a child eventually internalizes overt speech into conscious thought, a scientifically literate society could internalize computer generated analyses of brain scanning data.

It would only be a matter of adjusting to new methods of information extraction. If Ryle only wants to point out a sociological fact about current linguistic practice, then that is fine, and might still be philosophically illuminating in some respect. But such sociological commentary does nothing to diminish the metaphysical force of the physiologists who insists that perception is nothing but a bodily process in reaction to internal and external perturbations. And since we could imagine such bold metaphysical claims about perception catching fire and eventually establishing itself throughout the world’s language games, the facts Ryle discovers about psychological discourse are not necessary, but contingent.

In a way then, I have not shown that Ryle is wrong in his analysis of ordinary English use of verbs like “seeing”. Obviously Ryle is right that a peasant farmer is not referring to his or her inner brain states when proclaiming “I see the cows in the field”. But this is a contingent fact of history. If the farmer had been born in a different technological society, it is plausible that the facts might be different. Ryle’s point is that the current criteria for successful perception do not depend on any knowledge of physiology; we can know we or others have seen something without knowing anything about brain states. Acknowledging this, my point is that despite this current fact of how we understand the concept “seeing”, it does nothing to diminish the philosophical force of the materialist who insists that perceiving really is just an internal bodily process. The thing standing in the way of the materialist changing our language games then is not metaphysical truth, but only convention and inconvenience.

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Some thoughts on materialism, ontology, and the philosophy of mind

In my estimation, materialist or physicalist philosophy of mind has always occupied a rather strange place in the hierarchy of ideas since its coming to force in the 20th century and peaking with the “hard nosed” scientific reductionism and mind-brain identity theories in the 1950s. The strangeness arises because so many well respected scientific types accept  materialism and scientific reductionism dogmatically, yet it has a more problematic reputation in the philosophy of mind. David Chalmers is but one example of the sustained philosophical attack on the philosophical coherency of materialistic philosophy of mind. Of course, Chalmers would certainly consider himself to be a scientific monist of some sort and no doubt accepts the edicts of neuroscience without hesitation. Yet when it comes right down to it, he thinks materialism will fail as an explanation of certain mental phenomena, namely, qualia. The essence of these qualities is simply irreducible to materialistic ontology, and that’s that. Moreover, the dialectic in philosophy of mind has branched into a thousand debates about type vs token materialism, supervenience, emergentism, reductionistic physicalism vs nonreductionistic physicalism, identity theory, functionalism, and, of course, qualia, subjectivity, consciousness, experience, thoughts, beliefs, personal identity, action, and so on.

Reflecting on this twisted tangle of ideas is dizzying.  One feels as if in a labyrinth constructed entirely of neatly typed philosophy articles, all disagreeing with each other in very nuanced ways. The lack of consensus is overwhelming and, frankly, quite dispiriting. There are always revolutions within revolutions, counter-revolutions, and temporary intellectual victories, but, inevitably, the younger generations find “devastating flaws” in all preceding philosophical work. Every ten years you hear the great battle cry of “Start over!” and “Shake up the foundations!” It seems the mind sciences have always been this way.The radical shift between Jamesian psychology and Watsonian behaviorism is but one example to illustrate the “revolutionary” cliche that has crippled philosophy of mind. The once popular enterprise of exploring “deep generative grammar” is another example of rapid intellectual shifts that inevitably oversell themselves and overgeneralize their models at the expense of capturing genuine phenomena being discovered in rival labs (Chomsky’s hubris at trying to formally prove learning theories false is  embarrassing)

Everywhere we turn in the philosophy of mind we see various talk of “revolution”. I admit that I have, at times, given into the easy temptation to “turn the rugs over” and declare a sweeping intellectual coup, having at least grasped “what is truly the case”. Don’t get me wrong, I do think that a lot of “underbrush” needs to be swept away from our Cartesian and ontotheological heritage. We need to, for example, thoroughly expunge homuncular thinking, no easy task given that ontotheology is built into our linguistic forms of life. It is hard conceptual work to develop theoretical vocabularies that move away from that heritage, yet make enough sense as to be understood and accepted by the mind that is constructed by that heritage (since it is precisely  that mind which is faced with the task of consciously understanding the world around it).

Philosophy of mind then can be seen as a kind of exercise in conceptual experimentation or concept construction. Science investigates reality and philosophy generates the conceptual framework to talk about and understand that investigation. This is not an original statement. Thinkers before me (such as Deleuze) have accepted similar conceptions of what philosophy can and should do for science. When asked about his research in an interview, it is reported that Deleuze answered by saying “Bergson lamented that modern science lacked a metaphysics. I want to provide that metaphysics, and hence, I think of myself as a pure metaphysician.”

Metaphysics has a bad rap because of its historical associations with ontotheology and speculative pseudoscience. But I agree with Deleuze that we need to rehabilitate metaphysics. The classic essentialist ways of thinking simply cannot handle the complexity and dynamical properties being discovered in modern science, especially the life sciences. It seems that life has formed a brilliant habit of breaking all previous habits in the way it sustains itself through time. I contend, along with Deleuze and other developmentally oriented thinkers, that the problem of speciation and morphogenetic individuation is a paradigm model for thinking about the philosophy of mind. Deleuze helps us avoid problematic questions like, “What is the essence of the mind?”. Rather than talking about necessary and sufficient conditions, Deleuze wants to ask, “How did the mind evolve over time? What were the singularities and highest points of intensity that pushed/pulled humans into our contingent historical pathway?”

Some of my favorite points of highest intensity in human history include bipedalism, opposable thumbs, joint attention, tool construction, singing and music, symbolic thinking (systematicity in reference and compositionality), meta-awareness, introspection, theory of mind, philosophy, the scientific revolution, the information age, and, last but not least, the internet: the very tool that is allowing you, the reader, to hopefully receive these words as a stimulus for the development of interesting ideas in your brain many miles away. What do my readers think? What are the highest points of intensity for human evolution?

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