“What Is It Like to Be a Bat?” is an essay by the philosopher Thomas Nagel, published in The Philosophical Review in 1974. It is one of the most cited papers in the philosophy of mind, and it gave the field a durable way to talk about consciousness: the idea that an organism is conscious if there is “something it is like” to be that organism, from the inside. This subjective, first-person character of experience is what Nagel argues a complete science of the brain still leaves unexplained.
Nagel uses the bat deliberately because bats are mammals, clearly conscious, yet navigate the world through echolocation, a sense humans do not have. We can study a bat’s nervous system in full physical detail and still have no grasp of what its experience is actually like. Nagel’s point is not that bat minds are mysterious in some mystical sense, but that objective, third-person description - the only kind physical science offers - seems structurally unable to capture the subjective point of view that defines an experience.
The essay sharpened a problem that runs through later debates about machine consciousness. If understanding a brain in physical terms does not tell us what it is like to be that brain, then building or scanning an artificial system that behaves intelligently would not, by itself, tell us whether there is anything it is like to be that system. Nagel’s framing fed directly into David Chalmers’s “hard problem” of consciousness and the philosophical zombie argument, both of which press the gap between physical function and felt experience.
Why a general reader should care: as AI systems grow more capable and more humanlike in conversation, people increasingly ask whether they have inner experience. Nagel’s essay is the classic reason that question is hard - behavior and even full physical knowledge may not settle whether anyone is home.