What Is It Like to Be a Bat?

The paper addresses the mind-body problem by focusing on consciousness as its most intractable element. Nagel argues that prevailing reductionist and materialist approaches largely ignore or misconstrue the subjective character of experience—the fact that for any conscious organism there is something it is like to be that organism. He contends that without a clear account of this subjective character, attempts to reduce mental phenomena to physical descriptions are inadequate. The purpose is to show why standard models of scientific reduction (e.g., water=H2O, lightning=electrical discharge) fail to illuminate mind-brain relations and to motivate the need for new conceptual tools that can address consciousness’s essentially first-person character. The paper’s importance lies in reframing the mind-body problem around subjectivity and highlighting the current conceptual gap in physicalism.

Nagel engages with and critiques a wave of mid-20th-century reductionist and identity-theoretic accounts: J. J. C. Smart’s Philosophy and Scientific Realism; David K. Lewis’s argument for the identity theory; Hilary Putnam’s functionalism in "Psychological Predicates"/"The Nature of Mental States"; D. M. Armstrong’s A Materialist Theory of the Mind; and Daniel C. Dennett’s Content and Consciousness. He references his own earlier critiques of Armstrong and Dennett, and work on split-brain and unity of consciousness. He draws on Saul Kripke’s "Naming and Necessity" for arguments about the necessity of identity and the essential phenomenal character of experiences, and notes related concerns by M. T. Thornton. He cites Richard Rorty on mind-body identity and privacy. Later, he discusses Donald Davidson’s "Mental Events" (anomalous monism) as offering reasons to think mental events have physical descriptions even without strict psychophysical laws. Nagel also notes his own earlier paper "Physicalism" as related but still lacking a satisfactory conception of how psychophysical identity could be true.

Philosophical analysis and argumentation rather than empirical experimentation. The method includes: (1) conceptual clarification of the subjective character of experience as what it is like for an organism; (2) a thought experiment using bats—whose primary perceptual modality (sonar) is alien to humans—to illustrate limits of imaginative access and the essential tie between experience and a point of view; (3) comparison of mind-brain reduction with successful scientific reductions (e.g., lightning, rainbows) to demonstrate disanalogies; (4) analysis of subjectivity vs. objectivity and the role of viewpoint in constituting experience; (5) examination of identity statements and the deceptive clarity of "is" without a unifying theory; (6) consideration of Kripkean necessity/contingency issues and Davidson’s reasons for physical descriptions of mental events; and (7) a speculative proposal for an "objective phenomenology" capable of describing structural features of experiences in intersubjectively accessible terms.

- Conscious experience is essentially subjective: an organism is conscious iff there is something it is like for that organism to be that organism. This subjective character ties experience to a particular point of view. - Standard reductionist analyses (functional, intentional, causal-role, behaviorist) are logically compatible with the absence of subjective experience and therefore fail to capture what is distinctive about consciousness. - The bat example shows that human imaginative resources (even with detailed knowledge of bat physiology and behavior) yield at best a schematic, partial grasp of bat phenomenology. This illustrates the limits of extrapolating first-person concepts across radically different points of view. - There can be facts about experience that outstrip human conceptual and linguistic capacity; realism about subjective facts allows that there may be truths we cannot fully represent. - Objective physical theories characteristically abstract away from any specific point of view. Because experience’s essence is tied to a viewpoint, increasing objectivity (in the usual scientific sense) can move us farther from, not closer to, the nature of experience. - Successful reductions in science (e.g., lightning) preserve reference to a common external reality accessible from multiple viewpoints; by contrast, experience’s point of view is not merely a way of accessing an external object but is constitutive of the phenomenon itself, making standard reduction models inapplicable. - If mental processes are physical processes, then certain physical states would necessarily feel a certain way; however, we presently lack any conception of how such necessary connections could be true or explained. - Identity claims like "mental states are physical states" cannot be understood merely via the copula "is"; a theoretical framework is required to show how the referential paths converge. Without it, physicalism remains an unintelligible hypothesis despite possible indirect evidence. - There may be reasons (e.g., Davidson) to think mental events have physical descriptions, yet we still lack a theory that renders the psychophysical relation intelligible. - Proposal: develop an "objective phenomenology" to describe at least structural aspects of subjective experience in terms accessible to beings who do not share those experiences (e.g., explaining vision to someone blind from birth), potentially sharpening what aspects might admit physical explanation.

By foregrounding the subjective character of experience, Nagel reframes the mind-body problem: the central obstacle to reduction is not causation or function but the essentially perspectival nature of consciousness. The bat thought experiment demonstrates that experiential facts are bound to specific points of view, challenging the assumption that increased objectivity automatically yields a truer account of experience. This undermines analogies to standard scientific reductions and shows why existing materialist or functionalist theories leave the crucial phenomenon unaddressed. The discussion also connects to the problem of other minds: understanding how subjective experience could have an objective nature would clarify how other subjects’ experiences are possible and knowable. Nagel’s analysis suggests that physicalism may still be true, but we currently lack the conceptual resources to understand how; any adequate theory must explain how subjective character maps onto or is necessitated by physical states without erasing viewpoint-dependence. The proposed objective phenomenology offers a path to articulate structural features of experience that might be candidates for integration into objective (potentially physical) explanations.

Nagel concludes that current reductionist and physicalist accounts fail to address the subjective character of experience and thus cannot solve the mind-body problem. While physicalism might be true, we presently lack a conception of how it could be, given the inseparability of experience from a point of view. He calls for the development of an objective phenomenology to describe experiential structures in intersubjectively accessible terms as a prerequisite for any intelligible physical theory of mind. Future research should: (1) systematically analyze the subjective-objective divide; (2) develop descriptive frameworks for phenomenology that do not rely on empathy or direct imaginative transposition; and (3) explore theoretical models in which mental-physical relations are expressed using fundamental terms not neatly classifiable as purely physical or purely mental.

The paper offers no positive reduction or complete theory of consciousness; it is primarily negative and programmatic. It does not define "physical" precisely, sets aside detailed brain-level accounts, and relies on thought experiments that underscore epistemic limits rather than provide constructive mechanisms. The proposed objective phenomenology is speculative and acknowledged to be incomplete. The argument concedes that we may never fully access certain experiential facts due to human cognitive constraints, limiting generalizability and empirical testability.