Category: consciousness
Associated thinker(s): Thomas Nagel
Original publication or approximate period: What Is It Like to Be a Bat? (1974)
Difficulty: Beginner
Themes: subjectivity, perspective, explanation
Related experiments: marys-room, zombies
Kind: thought experiment
Research checked: 2026-10-30
Try to understand a bat’s experience of navigating through echolocation. You can learn about sound emissions, neural pathways, and flight. You can imagine hanging upside down or possessing wings. But imagining yourself behaving like a bat is not necessarily grasping how the world is experienced by a bat. Nagel uses this contrast to examine the subjective character that an account of consciousness must explain.
Can an objective description fully capture an experience available only from a particular point of view?
The example challenges the assumption that successful physical explanation can simply omit perspective. It asks what an adequate explanation of consciousness would need to preserve, while allowing that scientific understanding can improve.
Compare understanding an explanation of flight with acquiring the ability to fly. Science can explain flight without giving the reader wings; perhaps something similar holds for understanding experience without inhabiting another perspective. But the analogy may fail if subjectivity is part of the target phenomenon in a distinctive way. Identifying that difference is more productive than insisting either that descriptions must create experiences or that first-person facts are automatically irrelevant. The case invites a precise account of what successful explanation should provide and what limitations belong to the explainer.
Nagel emphasizes the difficulty of reducing subjective character to a perspective-independent description. Physicalist responses distinguish knowing all the facts from occupying the relevant perspective or possessing a practical imaginative capacity. Others seek scientific models that describe experiential structure without promising that reading a description produces the experience.
Nagel’s question is not whether humans can learn anything about bats. Nor is it simply a demand to feel exactly what another animal feels before studying it. The argument identifies a problem for reductive explanation; it is not a finished demonstration of a particular alternative metaphysics.
The knowledge argument gives the perspectival gap a different form by granting Mary all physical knowledge before a new experience. Comparisons with unfamiliar human senses help separate species differences from the general challenge of subjective understanding.
Stanford Encyclopedia of Philosophy, Qualia: The Knowledge Argument
Historical association: What Is It Like to Be a Bat? (1974). The sources above support the scenario and its intellectual context. Where an original work was not retrieved in full, its account is mediated by the named academic reference; no claim of full primary-source verification is made. The explanation and reflection questions here are original editorial prose.