Writing twenty four years later, Nagel's position (1998) remains essentially similar. In a nuanced, concluding passage, Nagel is very careful to distinguish between causation and entailment. He posits the need for an entirely novel, “third conception”:

even though no transparent and direct explanatory connection is possible between the physiological and the phenomenological, but only an empirically established extensional correlation, we may hope and ought to try as part of a scientific theory of mind to form a third conception that does directly entail both the mental and the physical, and through which their actual necessary connection with one another can therefore become transparent to us.

For Nagel a new theory-driven “solution to the mind-body problem” remains “unimaginable,” but he has moved to state that “it may not be impossible.”  

 

Nagel, Thomas (1974)What Is it Like to Be a Bat? Philosophical Review, 83: 4, October 1974, pp. 435-50.

Nagel, Thomas (1998) Conceiving the Impossible and the Mind-Body Problem. Royal Institute of Philosophy annual lecture, London: February 18, 1998. Published in Philosophy73: 285, July 1998, pp. 337-352.

 

UMWELT

Thomas Nagel’s is a somewhat reluctant anti-reductionist. His famed contribution (1074) to the mind/body controversy was to pose the bewildering question: "What is it like to be a bat?" Nagel chose:

bats instead of wasps or flounders because if one travels too far down the phylogenetic tree, people gradually shed their faith that there is experience there at all. Bats, although more closely related to us than those other species, nevertheless present a range of activity and a sensory apparatus so different from ours that the problem… is exceptionally vivid.

Furthermore:

anyone who has spent some time in an enclosed space with an excited bat knows what it is to encounter a fundamentally alien form of life.

Nagel quickly reminds us that bats:

perceive the external world primarily by sonar, or echolocation, detecting the reflections, from objects within range, of their own rapid, subtly modulated, high-frequency shrieks. Their brains are designed to correlate the outgoing impulses with the subsequent echoes, and the information thus acquired enables bats to make precise discriminations of distance, size, shape, motion, and texture comparable to those we make by vision .

Nagel challenges us to imagine “that one has webbing on one's arms, which enables one to fly around at dusk” or that—almost blind—one “perceives the surrounding world by a system of reflected high-frequency sound signals.” For Nagel this only goes so far:

it tells me only what it would be like for me to behave as a bat behaves. But that is not the question. I want to know what it is like for a bat to be a bat.

Nagel declares that:

we have at present no conception of what an explanation of the physical nature of a mental phenomenon would be.

We may be justified in believing “that sensations are physical processes,” but we are a long way from being poised “to understand how.” He characterizes the current “ status of physicalism” as

similar to that which the hypothesis that matter is energy would have had if uttered by a pre-Socratic philosopher.