Thomas Nagel: "What Is It Like to Be a Bat?" - The Philosopher Who Exposed the Irreducibility of Consciousness

Key Takeaways

• "What it is like": Consciousness has an irreducible subjective character. No matter how far physics advances, third-person description cannot derive first-person experience. This is why the mind-body problem will never be stamped "solved."
• "The View from Nowhere": Science pursues objectivity, yet the more thoroughly we describe the world in objective terms, the more subjectivity vanishes from the picture. But we cannot understand the world without subjectivity. This tension cannot be dissolved. Philosophy is the discipline that inhabits it.
• Mind and Cosmos: Materialist naturalism cannot explain the emergence of consciousness. Mutation and natural selection alone leave unexplained why the universe produced consciousness at all. Without appealing to theism, Nagel proposed the heretical hypothesis that nature itself harbors a teleological tendency toward mind.

Life and Historical Context

Thomas Nagel was born on July 4, 1937, in Belgrade, Yugoslavia, into a German-Jewish family. As the Second World War loomed, the family emigrated to the United States. Nagel has disclosed almost nothing about his childhood in public. He has never written an autobiography. He does not court readers with biographical drama. He lets arguments do the work.

In 1958 he graduated from Cornell University with a bachelor's degree in philosophy, then crossed the Atlantic to Oxford. At Corpus Christi College he took his BPhil in 1960. Oxford at the time was still thick with the atmosphere of ordinary language philosophy: J. L. Austin's linguistic analysis, Gilbert Ryle's behaviorism. The dominant strategy was to recast problems of mind as problems of language and dissolve them. Nagel absorbed the techniques of analytic philosophy thoroughly. He was not, however, convinced. The problem of mind, he sensed, was not the kind of thing that evaporated once you tidied up the language.

He returned to the United States and entered the graduate program at Harvard. His supervisor was John Rawls, who would go on to transform twentieth-century political philosophy with A Theory of Justice (1971). Under Rawls, Nagel wrote a doctoral dissertation on ethics: the rationality of altruism, the claim that reason itself grounds the capacity to treat another person's suffering as one's own concern. This work was later published as The Possibility of Altruism (1970). Even before he turned to philosophy of mind, the thread running through Nagel's thinking was already visible: do not erase subjectivity.

He received his PhD in 1963. After a period at the University of California, Berkeley, he joined Princeton University as a professor of philosophy in 1966. In 1980 he moved to New York University, where he has remained ever since as professor of philosophy and law. There are no colorful anecdotes. No scandals. He wrote papers quietly and quietly changed the philosophical landscape.

The intellectual context matters. The 1960s and 1970s were a period in which physicalism dominated Anglo-American philosophy. Mental states are identical with brain states (mind-brain identity theory: Smart, Place). Or mental states are defined by their functional roles (functionalism: Putnam, early Lewis). Either way, the prevailing optimism held that the "subjective feel" of consciousness was a problem that scientific progress would eventually dissolve. Nagel threw cold water on that optimism.

Mini Timeline

• 1937: Born in Belgrade, Yugoslavia
• 1958: Graduates from Cornell University (BA)
• 1960: Receives BPhil from Oxford University
• 1963: Receives PhD from Harvard University (supervisor: John Rawls)
• 1966: Appointed professor of philosophy at Princeton University
• 1970: Publishes The Possibility of Altruism
• 1971: Publishes "The Absurd"
• 1974: Publishes "What Is It Like to Be a Bat?"
• 1979: Publishes Mortal Questions (essay collection)
• 1980: Moves to New York University (NYU)
• 1986: Publishes The View from Nowhere
• 1997: Publishes The Last Word
• 2008: Awarded the Balzan Prize for Moral Philosophy
• 2012: Publishes Mind and Cosmos, igniting fierce controversy

What Question Does This Philosopher Ask?

Can consciousness be explained as part of the physical world?

Why did this question carry such explosive force? In mid-twentieth-century Anglo-American philosophy, attempts to reduce mind to matter had been rolling out one after another. Logical behaviorism (Ryle) claimed that talk about mind is really talk about behavioral dispositions: "pain" just means screaming, grimacing, favoring the injured area. Mind-brain identity theory (Smart, Place) went a step further: pain simply is a particular brain state, the firing of C-fibers. Functionalism (Putnam, early Lewis) defined mental states by their causal relations to inputs, outputs, and other mental states.

All three programs pointed in the same direction: render the mind objectively describable, capture it in the language of science, put it in a form that a third party can verify. Backed by the stunning successes of science, this direction carried overwhelming persuasive force.

Nagel pushed back head-on. Suppose your tooth aches right now. C-fibers are firing. Behavioral patterns are present. Functional roles are being fulfilled. Is that all? Even after you have exhausted every possible description, the feel of pain still remains. Between brain states and subjective experience there is a gap that will not close.

What Nagel changed was not the claim that "consciousness is an unsolved problem." His claim was sharper: "Consciousness is a problem that is in principle unsolvable within the current framework." It was a challenge to the comfortable optimism that science would eventually take care of it. The deficit is not in our knowledge; it is in our very mode of knowing.

Core Theories

1. "What Is It Like to Be a Bat?": The Subjective Character of Consciousness

The 1974 paper opens with a formulation that has become canonical: "the fact that an organism has conscious experience at all means, basically, that there is something it is like to be that organism" (p. 436). This phrase, "what it is like," became the keyword that dominated philosophy of mind for the next half-century.

Why a bat? Nagel chose an animal whose sensory modality is radically alien to our own. Bats perceive the world through echolocation: they emit ultrasound and construct spatial information from the returning echoes. Is echolocation like seeing? Like touching? Neither. An experience mediated by a sense organ that humans lack cannot be translated into human concepts.

In the paper, Nagel tries three imaginative approaches and demolishes all three (p. 439). Imagine adding echolocation to your own experience. Imagine subtracting vision. Imagine gradually transforming your human senses into bat senses. Each attempt terminates in the same place: what I would feel if I behaved like a bat, not what a bat feels as a bat. The subject never switches. Here is the wall.

Suppose neuroscience were fully mature and could describe every neuron's activity in a bat's brain: the mapping of brain regions involved in echolocation, mathematical models of signal processing, correlations with behavior. All of it in hand. Still, "what it feels like to perceive the world through echolocation" would not appear anywhere in the description. No amount of objective information yields subjective experience.

Nagel adds a careful caveat at the end of the paper: "it would be a mistake to conclude that physicalism must be wrong" (p. 446). We do not yet possess the concepts needed to understand the mind-body relation. Physicalism might be true, but within the current framework we cannot even say what its truth would mean. Do not rush to a solution; face the depth of the problem. That is the paper's real message.

The point was not to bury physicalism wholesale. The target was more limited, and for that reason more troublesome. The language of physics is designed to be independent of any particular viewpoint. Consciousness exists only from a particular viewpoint. Try to catch the latter in the net of the former and it slips through the mesh. The problem is not insufficient technology; it is that the net is woven the wrong way.

The philosopher Joseph Levine later gave this gap a name: the "explanatory gap." In a 1983 paper, Levine argued that even if the identity claim "pain = C-fiber firing" is true, an explanation of why it is true will be permanently missing. With "water = H₂O," one can derive water's properties (boiling point, transparency, solvent power) from the molecular structure. With "pain = C-fiber firing," no such derivation of the "feel of pain" is available. There is no logical bridge between physical description and subjective experience. Levine formalized in the precise vocabulary of analytic philosophy the intuition Nagel had articulated.

2. "The View from Nowhere": The Tension Between Subjective and Objective

Nagel's 1986 masterwork, The View from Nowhere, expanded the bat paper's insight into a full-scale philosophical system across eleven chapters. From the mind-body problem (Chapters 2-3) through knowledge and reality (Chapters 4-6), free will (Chapter 7), the foundations of ethics (Chapters 8-9), and death and the meaning of life (Chapter 10), the collision between subjective and objective recurs with the same structure. A single principle runs through all of philosophy.

We live with two eyes. One peers out at the world from inside our own body: the morning light is blinding, the train seat is cold, someone's voice lingers in my ear. The other tries to look down on the world from outside, including ourselves within it. Science trains this second eye to its limit: a description that belongs to no one's viewpoint. "The view from nowhere."

But the more completely you achieve this view, the more you lose. Color vanishes. Sound vanishes. Pain vanishes. The world of physics contains wavelengths and frequencies but no "redness." It contains air-pressure fluctuations but no "beautiful melody." The more objective you become, the further you move from the world in which we actually live.

Nagel does not ask you to choose one side. Both are real. To abandon the subjective view and flee into objectivity is a mistake; to abandon objectivity and retreat into subjectivity is equally a mistake. Philosophy is the practice of remaining within the tension that these two viewpoints generate. Not resolution but sustained tension. It is uncomfortable. But that discomfort, Nagel holds, is the human intellectual condition.

Free will makes the point vivid. From the subjective viewpoint, I "chose" to read this sentence. I could have closed the page. The sense of choice is visceral. But from the objective viewpoint, the viewpoint of neuroscience, my brain's states are simply transitioning in accordance with physical law. If determinism is correct, "choosing" is an illusion; if indeterminism is correct, randomness entered. Either way, objective description leaves no room for "I decided." Nagel presents this as a paradigm case of the failure of subjective and objective to mesh (The View from Nowhere, Chapter 7). To rescue free will, one must either compromise with compatibilism or admit the problem is unsolvable. Nagel takes the latter path. When a question cannot be answered, do not grab a cheap answer. That is his style.

3. Moral Realism: Reason Reaches Beyond the Self

The leap from consciousness to ethics may seem abrupt, but within Nagel's thought the two are continuous. The capacity to recognize that another person's pain is bad belongs, Nagel maintains, not to sentiment but to reason. Moral facts are not projections of the subject; they exist objectively.

The conceptual prototype appears in The Possibility of Altruism (1970): "agent-neutral reasons" (the term itself was established in The View from Nowhere). Just as my own hunger gives me a reason to eat, another person's hunger gives me, and every agent, a reason to act. Another's suffering is bad not because I happen to feel that way; suffering is bad whoever undergoes it. This "whoever" is agent-neutrality. The issue is not empathy. Reason, through its capacity to step outside one's own viewpoint and perceive structure, demands altruism.

This position is sharpened in The Last Word (1997). The relativist declares: "Reason has no universal authority; logic itself is a product of culture and history." Nagel's retort is clean: the very claim "reason has no universal authority" appeals to the universal authority of reason. Relativism undermines itself. To deny logic you must use logic. This self-refutation underwrites the authority of reason.

Here is the ethical application of "the view from nowhere." If you acknowledge that your own suffering is bad, then from the objective viewpoint you must also acknowledge that another person's suffering, structurally identical, is bad. The ground of altruism lies not in feeling but in the structure of reason itself.

In 1976, at a joint session of the Aristotelian Society, Nagel delivered "Moral Luck." At the same session Bernard Williams addressed the very same topic, and the two papers have been read as a pair ever since. The question: two drivers are equally careless, but a pedestrian steps into one car's path and not the other's. Outcomes differ, and so does moral judgment. Yet whether a pedestrian appeared was pure luck, beyond either driver's control. Moral assessment that hinges on factors outside the agent's control contradicts the principle at morality's root: that only what one can control is a proper target of moral evaluation. Morality's own premises collapse from within. The insight sent ripples through philosophy of law and criminal jurisprudence.

4. The Absurd: Self-Distancing as the Human Condition

Nagel's 1971 paper "The Absurd" approaches the theme from an angle quite different from Camus.

It opens by listing three popular reasons for calling life absurd and dismissing all three. (1) In a million years everything will be forgotten. But if what happens in a million years renders the present meaningless, then what happens now equally renders a million years hence meaningless. Temporal distance does not erase meaning. (2) We are tiny compared to the cosmos. But if humans were larger than the universe, would meaning materialize? Size and meaning are unrelated. (3) We could die at any time. Yet even immortality would not dissolve absurdity; it would make it permanent.

If none of the popular reasons hit the mark, where does absurdity actually come from? Nagel's answer locates it not in the universe but in us. Human beings possess the ability to "step back": to take one's life with full seriousness while simultaneously viewing that seriousness from outside and doubting it. Dogs and cats lack this capacity for self-distancing. That is why a dog is never tormented by absurdity. Only humans are. Camus located absurdity in the collision between the universe and the human being. Nagel locates it in a collision internal to the human being itself.

Consider a concrete case. You are desperately preparing for tomorrow's meeting, organizing materials, rehearsing your presentation. At the same time, somewhere in the back of your mind you think: "A hundred years from now, no one will remember." When these two viewpoints collide, the internal seriousness and the external doubt, absurdity arises.

Nagel's prescription is not heroic defiance. It is irony. After recognizing absurdity, we go on preparing for the meeting, packing the children's lunches, brushing our teeth. We carry on with daily life in full awareness of its cosmic pointlessness. Nagel writes: "If sub specie aeternitatis there is no reason to believe that anything matters, then that doesn't matter either, and we can approach our absurd lives with irony instead of heroism or despair" (p. 727).

5. Mind and Cosmos: A Declaration of War on Materialism

In 2012, Nagel dropped a bomb. Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False. The subtitle alone was a provocation.

The book has five chapters. After an overview in Chapter 1, Chapter 2 lays out a general critique of reductionism, and the remaining three chapters hammer at three domains where materialism stumbles. Chapter 3, "Consciousness": why does subjective experience arise from matter? The question Nagel had carried since 1974. Chapter 4, "Cognition": why can our brains grasp the world correctly? Natural selection preserves beliefs that are useful for survival, but there is no guarantee that survival-useful beliefs are true. Chapter 5, "Value": can moral judgments be derived from physical facts? By mutation and selection alone, how did blind matter give rise to moral cognition? The three questions share a single root: within the causal motion of matter, there is no place for experience, truth, or goodness.

Nagel answers in the negative. Evolution brilliantly explains changes in form and adaptation. But "why a specific configuration of matter produces subjective experience" lies outside evolution's jurisdiction. That is a question for the laws of physics, and the laws of physics are silent on consciousness.

His alternative was bold. Nature itself harbors a tendency toward mind, a "teleological tendency." The universe is not driven by accident alone; the emergence of consciousness and reason is woven into the natural order. This is not an appeal to God. It is an immanent teleology of nature: a vision close to Aristotle, revived in a twenty-first-century context.

The book ignited a firestorm. Brian Leiter and Michael Weisberg wrote in their review that "it is rare for a sophisticated thinker to be so wrong." Steven Pinker on Twitter was barely short of telling Nagel to retire. A widespread misreading held that an atheist had sided with Intelligent Design (Nagel is an atheist and does not endorse Intelligent Design). But the question itself will not go away. Does current science truly explain how consciousness emerges from matter? If you face that question honestly, the answer is clear: not yet.

Guide to Major Works

• "What Is It Like to Be a Bat?" (1974): The sixteen-page paper that became a turning point in philosophy of mind. It argues that the subjective character of consciousness cannot be reduced to physical description. The single indispensable starting point for engaging with Nagel.
• Mortal Questions (1979): An essay collection that includes the bat paper alongside gems such as "The Absurd," "Moral Luck," and "Death." Remarkably lucid prose accessible even without philosophical training.
• The View from Nowhere (1986): Nagel's magnum opus. Develops the tension between subjective and objective across the mind-body problem, epistemology, ethics, and free will. The single volume that captures his philosophy as a whole.
• The Last Word (1997): A counterattack on relativism and subjectivism. Defends the objective authority of reason in logic, science, and ethics. Short and sharp.
• Mind and Cosmos (2012): His most controversial work. Argues that materialist naturalism cannot account for consciousness, cognition, or value, and proposes an immanent teleology in nature. Whatever one's verdict, the scope of the questions makes it worth the effort.
• What Does It All Mean? A Very Short Introduction to Philosophy (1987): A philosophy primer accessible to high-school students. In under a hundred pages it covers the mind-body problem, free will, death, justice, and the meaning of life. Its style of opening questions rather than closing them is pure Nagel. The ideal entry point for a first encounter with philosophy.

Major Critiques and Controversies

Daniel Dennett stands as Nagel's great antagonist: a near-contemporary who occupies the diametrically opposite position. Dennett denies the very existence of the "subjective feel" of consciousness. Qualia, the redness of red, the painfulness of pain, are an illusion. Consciousness is a mode of information processing in the brain; function is all there is. The "something it is like" is a fiction generated by the brain when it narrates its own processing. For Dennett, Nagel's argument merely "converts a failure of imagination into an ontological conclusion." The inability to imagine bat experience and the irreducibility of bat experience to objective description are two different things.

The disagreement runs deep. Dennett does not budge. The "hard problem" of consciousness is unsolvable because the question is malformed, he insists. Nagel shakes his head. When your tooth throbs right now, can you nod in agreement that "the pain is merely a mode of information processing in the brain"? If you cannot, you stand with Nagel. If you can, you stand with Dennett. Philosophy of mind splits in two at this seam.

The reaction to Mind and Cosmos was even more ferocious. Many scientists and philosophers accused Nagel of misunderstanding evolutionary theory. Evolutionary biologist Elliott Sober pointed out that Nagel underestimates the explanatory power of natural selection. A fair criticism. But Nagel's target is not internal to biology. Natural selection can explain why organisms with consciousness enjoy a survival advantage. It cannot explain why a configuration of matter gives rise to consciousness in the first place. The former is a question for biology; the latter is a question for metaphysics. Nagel is asking the latter.

In Japan, the philosopher Hitoshi Nagai developed Nagel's problematic in a distinctive direction. Nagai radicalized the question of the "I" (what he calls the unparalleled uniqueness of this "I"), pushing it further than Nagel into what he terms dokuzairon (the thesis of the solitary existent). Where Nagel asks about the general structure of consciousness, "what is it like to be an organism," Nagai asks: "Why is it I who am I, rather than anyone else?" The question drops one level deeper.

Influence and Legacy

The ripples from those sixteen pages in 1974 are still spreading.

David Chalmers coined the "Hard Problem of consciousness" in 1995, essentially giving Nagel's explanatory gap a new banner. Why does subjective experience accompany the physical processes of the brain? This is qualitatively different from the "easy problems" of explaining function and behavior. Chalmers has since gone further, seriously considering panpsychism, the thesis that even the basic constituents of matter harbor a primitive form of consciousness, a direction that overlaps with the trajectory suggested in Nagel's Mind and Cosmos.

Frank Jackson's "Knowledge Argument" (1982) also stands in Nagel's shadow. Mary, a brilliant color scientist, has been confined to a black-and-white room her entire life. She knows every physical fact about color vision. But when she steps outside and sees red for the first time, does she learn something new? If she does, then physical knowledge is not everything. Nagel's bat and Jackson's Mary hit the same wall from different angles.

In ethics, Nagel's moral realism resonates with Derek Parfit's Reasons and Persons (1984) and On What Matters (2011): the shared conviction that reason can reach moral truths that transcend the individual subject. Parfit called Nagel "one of the most important living moral philosophers."

Beyond philosophy, Nagel's footprint extends into neuroscience and AI research. When neuroscientists search for the "neural correlates of consciousness" (NCC), the question of how to bridge the gap between "correlation" and "identity" is Nagel's question exactly. In artificial intelligence, the philosophical foundation of "does a machine have consciousness?" rests on Nagel's "what it is like."

Connection to the Present

The text you are reading right now might have been written by a large language model. It answers questions, cracks jokes, even composes poetry. From the outside it looks like "thinking." But is there something it is like to be that system? When it predicts the next token, does experience inhabit that process? No behavioral test can settle the matter. Without an inside view, "thinking" cannot be attributed. And there is no window into the inside. Nagel's question resonates in 2026 far more urgently than it did in 1974.

Brain science continues to pursue the "correlates" of consciousness. fMRI renders brain activity visible, pairing specific experiences with specific neural firing patterns. Yet "why that particular firing pattern is accompanied by the experience of red" remains, as ever, unwritten. Correlation is not explanation. The gap Nagel identified fifty years ago has, if anything, become more conspicuous as technology advances.

The debate over animal consciousness connects here as well. Do the pigs and chickens in factory farms experience suffering, a "feel" of pain? If they do, is it morally permissible to process them industrially while ignoring that suffering? Nagel's framework blocks the easy escape. "We cannot confirm it, therefore it does not exist" is not a valid inference. Precisely because we cannot peer inside, there are things we must not trample.

Questions for the Reader

• Is the "red" you see right now the same experience as the "red" the person beside you sees? Is there any way to verify this?
• When an AI outputs "I am conscious," what grounds do you have for denying it? How do those grounds differ from the grounds on which you believe the person next to you is conscious?
• Have you ever lived your life with full seriousness while simultaneously doubting that seriousness "from the outside"? When those two viewpoints collided, which self did you trust?

References

• (Primary text): Thomas Nagel, "What Is It Like to Be a Bat?", The Philosophical Review, Vol. 83, No. 4, 1974, pp. 435-450.
• (Primary text): Thomas Nagel, The View from Nowhere, Oxford University Press, 1986.
• (Primary text): Thomas Nagel, Mind and Cosmos: Why the Materialist Neo-Darwinian Conception of Nature Is Almost Certainly False, Oxford University Press, 2012.
• (Primary text): Thomas Nagel, The Last Word, Oxford University Press, 1997.
• (Primary text): Thomas Nagel, The Possibility of Altruism, Princeton University Press, 1970.
• (Study): David Chalmers, The Conscious Mind: In Search of a Fundamental Theory, Oxford University Press, 1996.
• (Article): Joseph Levine, "Materialism and Qualia: The Explanatory Gap", Pacific Philosophical Quarterly, Vol. 64, 1983, pp. 354-361.
• (Primary text): Thomas Nagel, Mortal Questions, Cambridge University Press, 1979.
• (Primary text): Thomas Nagel, What Does It All Mean? A Very Short Introduction to Philosophy, Oxford University Press, 1987.
• (Overview): "Thomas Nagel", Internet Encyclopedia of Philosophy.
• (Overview): "Thomas Nagel", Stanford Encyclopedia of Philosophy, https://plato.stanford.edu/entries/nagel/