If we’re to believe science, we’re made of organs and cells. These cells are made up of organic matter. Organic matter is made up chemicals. This goes all the way down to strange entities like quarks and Higgs bosons. We’re also conscious, thinking things. You’re reading these words and making sense of them. We have the capacity to reason abstractly and grapple with various desires and values. It is the fact that we’re conscious and rational that led us to believe in things like Higgs bosons in the first place.
But what if science is fundamentally incapable of explaining our own existence as thinking things? What if it proves impossible to fit human beings neatly into the world of subatomic particles and laws of motion that science describes? In Mind and Cosmos (Oxford University Press), the prominent philosopher Thomas Nagel’s latest book, he argues that science alone will never be able to explain a reality that includes human beings. What is needed is a new way of looking at and explaining reality; one which makes mind and value as fundamental as atoms and evolution.
For most philosophers, and many people in general, this is a radical departure from the way we understand things. Nagel, according to his critics, has completely lost it. Linking to one particularly damning review in The Nation, Steven Pinker tweeted, “What has gotten into Thomas Nagel? Two philosophers expose the shoddy reasoning of a once-great thinker.”
Nagel’s pessimism about science’s ability to explain things like consciousness has a long history. In his seminal 1974 essay “What is it like to be a bat?”, he argues that even if you knew every single physical fact about someone, you’d still have no idea what it is like to be them. I could know everything there is to know about perception, but I’ll never know what it feels like to be colour-blind, save some horrible accident. Similarly no matter how much we know about bats' ability to use echolocation we can never really know what it is like to be a bat flying about in the dark, navigating with reverberating sound waves. So, given that we are all conscious beings, it seems science is missing out on something quite fundamental. There are facts, or parts of reality, it leaves behind.
Nagel’s argument has been criticised in a variety of ways. Philosophers like Daniel Dennett or Paul Churchland argue that Nagel’s whole approach is flawed. We are of course conscious, but consciousness is a phenomenon that can eventually be explained by science the same way heat and colour are. The residual “what-its-like-ness” is just an outdated term with no real meaning, rather like obsolete scientific theories about the “ether” or “phlogiston.”
But this line of attack is hard to accept. To us it really does feel as if there is something “it-is-like” to be conscious. Besides their strange account of consciousness, Nagel’s opponents also face the classic problem of how something physical like a brain can produce something like a mind. Take perception: photons bounce off objects and hit the eye, cones and rods translate this into a chemical reaction, this reaction moves into the neurons in our brain, some more reactions take place and then...you see something. Everything up until seeing something is subject to scientific laws, but, somewhere between neurons and experience, scientific explanation ends. There is no fact of the matter about how you see a chair as opposed to how I see it, or a colour-blind person sees it. The same goes for desires or emotions. We can look at all the pieces leading up to experience under a microscope, but there’s no way to look at your experience itself or subject it to proper scientific scrutiny.
Of course philosophers sympathetic to science have many ways to make this seem like a non-problem. But in the end Nagel argues that simply “the mind-body problem is difficult enough that we should be suspicious of attempts to solve it with the concepts and methods developed to account for very different kinds of things.” And I think many of us are sympathetic to this line of reasoning.
Nagel, however, goes much further, which is what makes Mind and Cosmos interesting. Even if we agree with him that consciousness presents a serious problem for the idea that science can explain all of reality, Nagel’s next move is more controversial. He asks what reason there can be for the existence of consciousness. He rules out intelligent design and God, and even evolution. Nagel concludes, in a vein similar to the German idealist philosophers of the late 18th and early 19th century, that the nature of reality is such that there is a natural progression towards consciousness.
By this stage Nagel’s argument might have begun to appear absurd. However, he begins with modest considerations. It seems reasonable to suppose that for every truth there must be an explanation for why it is the case, often called “the principle of sufficient reason.” One may be tempted to deny this. There may be some inexplicable truths. But then one is faced with justifying why no explanation is needed. Why not just accept the brute fact that objects fall rather than bothering with Newtonian physics? There may be inexplicable facts deep in the fabric of reality, but most of them need explanation. One such fact that needs explaining is that there are conscious beings.
What sort of explanations are there for human consciousness? One is that there is some God or supernatural entity out there who endowed us with consciousness. But this explanation comes with its own vast set of problems. What is the explanation for God’s existence? Is he a part of nature? If not how can he cause things? Is he omnipotent? Can he create a boulder so big he can’t move it, and so on.
Another explanation looks to the theory of evolution. Darwin’s account of evolution, broadly speaking, says that animals' traits will largely be determined by the environment they have existed in—namely the traits that allow one organism to survive and reproduce rather than another. Thicker furs in colder climates and sharper teeth for carnivores are good examples of adaptive traits. Consciousness could be like teeth or fur; a trait that allowed our ancestors to survive and reproduce. However, the principle of sufficient reason resurfaces. What does being conscious add, in terms of pure adaptability, over and above having really good adaptive behavioural patters? Why aren’t we unconscious primates who unreflectively go about our business?
Seeing these problems Nagel concludes that the Darwinian answer is irreparably flawed. Ruling out divine intervention or design, evolution, and inexplicability, what reason is there left to explain consciousness? The only remaining answer, Nagel argues, is that on a fundamental level there is an end towards which the cosmos is naturally inclined: a natural teleology. Part of this natural teleology is a tendency for there to be creatures that are conscious. The universe, in a way of speaking, wants to become conscious. This conclusion may look no less strange or absurd than when I first introduced it, but it is at least clear that Nagel did not pluck it out of thin air. And even if we do not agree with his conclusion, the route he takes to arrive there raises many serious questions for philosophical naturalism (the theory that science exhaustively explains the universe).
I have overlooked two significant aspects of Nagel’s book. In addition to all the problems surrounding consciousness, Nagel argues that things like the laws of mathematics and moral values are real (as real, that is, as cars and cats and chairs) and that they present even more problems for science. It is harder to explain these chapters largely because they followed less travelled paths of inquiry. Often Nagel’s argument rests on the assumption that it is absurd to deny the objective reality, or mind-independence, of certain basic moral values (that extreme and deliberate cruelty to children is wrong, for instance) or the laws of logic. Whether this is convincing or not, depends on what you think is absurd and what is explainable. Regardless, this gives a sense of the framework of Nagel’s argument and his general approach.
As often happens when a philosopher deviates from scientific orthodoxy, Nagel’s book has been thoroughly denounced. Brian Leiter and Michael Weisberg, in their highly critical review for The Nation, led the charge, asking, “Are we really supposed to abandon a massively successful scientific research program because Nagel finds some scientific claims hard to square with what he thinks is obvious?” Elliott Sober, in the Boston Review, wrote “[Nagel] argues that evolutionary biology is fundamentally flawed and that physics also needs to be rethought—that we need a new way to do science.” Nonetheless, says Sober, “Nagel acknowledges that he has no teleological theory of his own to offer. His job, as he sees it, is to point to a need; creative scientists, he hopes, will do the heavy lifting.”
Now to my knowledge at no point in Mind and Cosmos (or elsewhere) does Nagel suggest that scientists put down their microscopes, shut down their particle accelerators, and abandon their research programmes. In fact he explicitly states that “For all I know, most practicing scientists may have no opinion about the overarching cosmological questions...their detailed research and substantive findings do not in general depend on or imply [materialist reductionism] or any other answer to such questions.”
What Nagel does suggest is that philosophers, or scientists who wish to provide philosophical insight look at the relationship between mind and nature in a different way. In particular, philosophers should stop assuming that reality will one day be exhaustively explained by science, and start trying to incorporate other methods of explanation into our worldview.
In response, philosophers like Weisberg and Leiter and Sober tend to dig their heels in, reiterate the pragmatic values of science, and conclude that these values are sufficient to justify philosophical naturalism. But this is not a satisfactory counterargument. Nagel and most critics of naturalism agree that our best methodology for predicting and manipulating natural phenomena is science. But why suppose that reality is exhaustively described by science in its current form? There are plenty of things that aren’t obviously describable in scientific terms which are part of reality: mathematics, logic, language, history, and, here we go again, consciousness. It is never going to be possible to put these under a microscope.
There is also no obvious reason why the scientific method (granting that there is a coherent singular scientific method and content, which is itself dubious) warrants one picture of reality over another. A scientist might share Nagel’s philosophical perspective, but this won’t make any difference in the lab. There s/he will get along just fine with scientists who hold the more common materialist/naturalist metaphysical viewpoint. They’ll both have the same conditions for falsification and crafting a hypothesis and they’ll both read the same studies and keep the same standards for accuracy. In fact it’s hard to see if they’d ever know each other’s respective worldviews unless during a lunch break an impromptu debate on metaphysics breaks out.
Of course Weisberg-Leiter, Sober, and others have answers to these criticisms. These debates are not new, and they’ve generated mountains of books and papers in the philosophy of science, mind, metaphysics, and epistemology. Regardless, one of the motivating factors behind Nagel’s book, one largely glossed over by his critics so far, is that even with the extraordinary success of science, there is no obvious way it could account for things like consciousness, rationality, or moral values. We can disagree with Nagel that those things need to be part of our picture of reality. We can disagree with Nagel that there must be one coherent way of describing reality. We can even disagree with Nagel that there is an appearance-reality distinction. But we can’t keep gesturing to science’s great pragmatic value as a way of papering over its incomplete metaphysics.
Mind and Cosmos is ambitious in scope, philosophically creative, decently written, and, most importantly, short. This makes it more enjoyable and readable than most philosophy titles out there, which are getting worryingly larger in volume and narrower in scope. Nagel’s arguments against naturalism as an account of reality are powerful and demand close consideration, even if his positive arguments for a natural teleology end up looking every bit as intuitively implausible as a description of reality that leaves out consciousness.
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