What Is It Like to Be a Bat?

One of the most famous questions in philosophy of mind sounds almost strange at first. What is it like to be a bat?

This question comes from a well known paper by philosopher Thomas Nagel (https://philosophy.uconn.edu/wp-content/uploads/sites/365/2020/03/Nagel-What-is-it-like-to-be-a-bat.pdf). In it, he argues that even if science could explain every physical fact about a bat’s brain and body, there might still be something missing. That missing piece is the subjective experience of being that creature.

We can study bats from the outside. We can measure their brain activity, analyze their behavior, and understand how their sensory systems work. But Nagel asks whether that kind of knowledge can ever tell us what it actually feels like to exist as a bat.

His argument is not really about bats. It is about the limits of objective knowledge and the nature of conscious experience itself.

The Problem of Subjective Experience

Modern science is very good at explaining systems objectively. It describes the world in terms of physical structures, processes, and measurable interactions. This approach has worked remarkably well for physics, biology, and neuroscience.

But conscious experience seems different. When you see the color red, hear music, or feel pain, there is something it is like to have that experience. This inner perspective is sometimes called subjective experience.

Nagel’s claim is that subjective experience cannot be fully captured by objective descriptions. A scientific explanation can tell us how neurons fire or how signals move through the brain. It can describe the mechanisms behind perception. Yet those descriptions still seem to leave out the actual feeling of the experience.

The challenge is that science usually explains systems from the outside. Consciousness, however, seems to involve a perspective from the inside.

Why a Bat?

Nagel chose bats because their sensory world is very different from ours. Humans rely mostly on vision. Bats rely heavily on echolocation, a system where they emit high frequency sounds and interpret the echoes that bounce back from objects around them.

From a scientific point of view, we can understand echolocation quite well. Researchers can measure the sounds bats produce, study how their brains process echoes, and model the information they receive about their environment.

But even with that knowledge, we still cannot imagine what echolocation actually feels like. Our brains are built for vision and hearing in the human range. We cannot simply translate a bat’s sensory experience into our own.

This is exactly Nagel’s point. Understanding the mechanisms of a system does not automatically give us access to the experience associated with that system.

Bats navigate using echolocation. They emit high frequency sounds and analyze the returning echoes to detect objects and movement. Although scientists understand this process in detail, the subjective experience of perceiving the world through echolocation remains impossible for humans to imagine directly.
"What is Echolocation?", ASU - Ask A Biologist, Nov 4 2009. https://askabiologist.asu.edu/echolocation

Objective Knowledge and Its Limits

Nagel argues that science aims for objectivity. It tries to describe the world in ways that do not depend on any particular observer. The more objective a description becomes, the more it removes the perspective of individual experience.

This works well for many kinds of problems. Physics describes motion and energy without needing to refer to anyone’s personal viewpoint. Chemistry explains reactions without describing how molecules feel from the inside.

But consciousness seems tied to perspective. Every experience belongs to a specific point of view. It exists only for the organism having it.

Because of this, Nagel suggests that an entirely objective science may always leave something out when it tries to explain consciousness. The inner character of experience might not be reducible to physical descriptions alone.

This does not mean neuroscience is wrong. It means that explaining mechanisms and explaining experience might be different kinds of understanding.

The Gap Between Explanation and Experience

To see the gap Nagel describes, imagine learning everything about color vision from textbooks. You might study wavelengths of light, retinal cells, and neural pathways in the brain. You could know every scientific fact about how color perception works.

But if you had never actually seen color, those facts might still feel incomplete. The moment you finally saw red for the first time, something new would appear in your understanding. You would know what the experience is like. (This is essentially the Mary's room thought experiment.)

Nagel believes this gap between description and experience is not just temporary. It reflects a deeper feature of consciousness. Some aspects of reality might only be accessible from the perspective of the organism experiencing them.

What This Means for the Study of Mind

Nagel’s argument does not claim that consciousness is supernatural or beyond science. Instead, it challenges the assumption that objective explanations alone can capture everything about the mind.

If subjective experience is an essential feature of consciousness, then understanding the mind may require more than just describing physical processes. It may also require recognizing that some aspects of reality are tied to perspective.

This idea has influenced many debates in philosophy of mind, including discussions about qualia, artificial intelligence, and the possibility of understanding other minds.

Nagel’s bat reminds us that even with all our scientific knowledge, there may still be dimensions of experience that cannot be fully translated into objective language.