Thomas Nagel is an American philosopher at NYU whose work concerns the limits of objective description — in philosophy of mind, in ethics, and in how a person relates to their own life.

What is it like to be a bat?

His 1974 paper argues that an organism has conscious experience if there is something it is like to be that organism. Bats navigate by echolocation, a mode of perception we do not have. We can describe the mechanism completely and still have no access to the character of the bat's experience.

The conclusion is not that consciousness is non-physical. It is that physical description proceeds by moving away from any particular point of view, and consciousness is defined by having one — so the usual method of explanation has nothing to grip. The paper reframed the subject and is the direct ancestor of the hard problem.

The view from nowhere

His 1986 book develops the same tension more broadly. Human beings can take an objective view of themselves, seeing their own life as one among many and their concerns as no more important than anyone else's. We also cannot stop living from the inside, where our own concerns are overwhelming.

Nagel argues that neither view can be discarded, and that many philosophical problems — free will, the meaning of life, the weight of morality — are what the collision between them looks like.

Ethics

In ethics he defends the view that reasons can be objective: that "it hurts" gives anyone a reason to help, not only the person hurt. The position is argued against the widespread assumption that reasons must ultimately trace back to someone's desires.