“What Is It Like to Be a Bat?”

Thomas Nagel, The Philosophical Review, vol. 83, no. 4, 1974

A being is conscious if there is something it is like to be it — and that subjective point of view resists every objective description.

There is something that it is like to be that organism.
Thomas Nagel, 1974

What the text says

Nagel chooses the bat because it is close enough to us to be almost certainly conscious, and far enough away for its experience to escape us: it perceives the world by echolocation. We can learn everything about its sonar, its neurons, its behaviour. We still will not know what it is like to be a bat.

The paper does not claim that physicalism is false. It argues that we do not yet understand what it could mean for it to be true: how a fact seen from the inside could be identical to a fact described from the outside.

Why read it now

Our machines are the exact reverse of the bat: we know everything about how they work, and they speak our language. Yet Nagel’s question remains untouched. Understanding how a system works does not tell us whether there is anyone there to experience it.

What remains open

What kind of evidence could tell us what it is like to be a machine — if it is like anything at all?