Nagel’s Bat and the Explanatory Gap

Nagel’s bat: preliminaries Phenomenal consciousness is what makes the mind-body problem hard Materialist analyses leave out what it is like

Nagel’s bat: preliminaries How do materialist analyses leave out what it is like?

Nagel’s bat: preliminaries Consider the type-identity theory: pain = c-fiber stimulation This leaves out what it’s like to feel pain. For I can imagine feeling pain without my c-fibers firing and vice versa. Or consider functionalism:

Nagel’s bat: preliminaries Pain = whatever plays causal-role X (is produced by damage to the body and produces avoidance behavior, and… This too leaves out what it’s like to feel pain, for something could play causal-role X without it feeling the way pain feels.

Nagel’s bat: the thread of the argument What is it like to be a bat? Can there be a physical account of what it is like?

Nagel’s bat: the thread of the argument Bats are alien: We can’t have bat experiences (e.g. echolocatory experiences), we can’t even imagine what such experiences are like.

Nagel’s bat: the thread of the argument You think you can imagine it because you can imagine what its like to hang upside down, emit high-pitched shrieks in order to navigate, etc. But this gets you only what it would be like for you to behave as a bat behaves. The question is: What it is like for a bat to be a bat?

Nagel’s bat: the thread of the argument Experiences are private. You can’t have my token experiences. Is this all that is being claimed? No. These what-it-is-likenesses are mental types that different subjects can instantiate. But they are subjective; they embody a point of view.

Nagel’s bat: the thread of the argument Physical facts, by contrast, are objective— accessible from many points of view. Thus the difficulty in seeing how the facts about what it’s like to be a bat could be physical. The clash between the subjective and the objective.

Nagel’s bat:the thread of the argument “…if the facts of experience-facts about what it is like for the experiencing organism-are accessible only from one point of view, then it is a mystery how the true character of experiences could be revealed in the physical operation of that organism. The latter is a domain of objective facts par excellence…” (p. 522)

Nagel’s bat:the thread of the argument The problem from another angle: Typical cases of theoretical reduction (the model for materialist analyses) proceed by excluding the phenomenological. Heat = molecular motion

Nagel’s bat:the thread of the argument Sensations play no role, except to fix the reference of the term for thing reduced. Heat is whatever produces heat-sensations in us and that property is, objectively, the motion of molecules.

Nagel’s bat:the thread of the argument But when it comes to reducing the sensations themselves, there is no excluding the phenomenological; there is no appearance/reality distinction with respect to the sensations: pains = feelings of pain.

Nagel’s bat: the conclusion Does Nagel think that we can conclude that materialism is false? No. It’s just that we have no conception of how it could be true.

The explanatory gap Inspired by Nagel, some philosophers say that even if materialism is true, we will never understand or explain the mind in physical terms.

The explanatory gap The focus for those who push versions of the thesis that there is an explanatory gap between the mental and the physical is phenomenal consciousness. The intuition is this: No matter how much we learn about the structure of the brain, nothing that we learn will explain to us why we have these sorts of experiences.

The explanatory gap Nothing will explain why we have these as opposed to completely different ones Or these as opposed to none at all. Spectrum inversion Zombies The connection between the physical and the phenomenal appears arbitrary.

The explanatory gap Van Gulick’s reply: If the explanatory gap intuition is supposed to be generated by the simplicity of experiences--by their having no structure--then the intuition can be met. Experiences do have structure. Binary vs. unary hues The affective dimension of phenomenal color.

The explanatory gap At best, Van Gulick’s reply succeeds against the spectrum inversion justification for the explanatory gap. But what about the zombie justification?