qualia and the case against physicalism, including Jackson's knowledge argument and Nagel's bat

What this dot point is asking

VCAA wants you to explain what qualia are, reconstruct the two most famous arguments that they pose a problem for physicalism (Frank Jackson's knowledge argument and Thomas Nagel's bat), and evaluate the physicalist responses. The high-band answer states the knowledge argument as valid premises, identifies that physicalists must attack the premise that Mary learns a new fact, and weighs the ability and acquaintance replies.

What qualia are

Qualia (singular: quale) are the introspectible, qualitative characters of conscious experience: the particular way red looks, the way coffee tastes, the throb of a headache. They are what behaviourism leaves out and what the explanatory gap is a gap about. The case against physicalism is that no description in the vocabulary of physics, chemistry and neuroscience, however complete, seems to capture these felt qualities, which suggests there are facts about the mind that physicalism cannot accommodate.

Jackson's knowledge argument

Frank Jackson, in Epiphenomenal Qualia, presents the case of Mary. Mary is a brilliant scientist who has lived her whole life in a black-and-white room and learned, through black-and-white books and screens, every physical fact there is about colour and colour vision: wavelengths, retinal processing, the neuroscience of seeing red. Reconstructed:

1. Before release, Mary knows all the physical facts about colour vision.
2. On release, when she sees a red tomato for the first time, she learns something new: what it is like to see red.
3. So there was a fact she did not know before, despite knowing all the physical facts.
4. Therefore not all facts are physical facts.
5. Therefore physicalism is false.

The argument is valid. Its force is that step 2 seems undeniable: surely Mary gains something on seeing colour, and that something is not contained in any physics textbook.

Nagel's bat

Thomas Nagel, in What Is It Like to Be a Bat?, argues that an organism has conscious experience just in case there is something it is like to be that organism. A bat navigates by echolocation, a mode of perception utterly unlike ours. We can describe the physics and physiology of echolocation completely, yet we still have no idea what it is like, from the inside, to perceive the world by sonar. The point: physical descriptions are objective, available from any point of view, while consciousness is essentially subjective, tied to a single point of view. So a complete objective physical account necessarily omits the subjective character of experience, the very thing that makes it conscious.

Evaluation

The arguments share a structure: there is knowledge or a fact accessible only from the first-person standpoint, and physical descriptions are third-person, so physical descriptions are incomplete. The most effective physicalist replies attack premise 2 of the knowledge argument, denying that Mary learns a new fact.

The ability reply (Lewis, Nemirow) says Mary gains know-how, not knowledge-that. She acquires new abilities, to recognise, imagine and remember red, but no new propositional fact about the world. Learning what red is like is learning to do something, not learning that something is the case, so no non-physical fact is needed. This is the strongest response, though critics object that Mary plausibly does learn a new truth (so that is what they have been seeing), not merely a skill.

The acquaintance reply says Mary gains a new way of being acquainted with a fact she already knew, the old physical fact under a new, phenomenal mode of presentation, much as one can know that the morning star is bright without knowing the evening star is bright, though they are one planet. She gains no new fact, only a new mode of access. Jackson himself later abandoned the argument, partly worried that qualia so construed would be epiphenomenal and that an evolutionary explanation of why we believe in them would undercut the case.

Nagel's argument is harder to defeat because it does not claim qualia are non-physical, only that our current concepts cannot capture subjectivity. A physicalist can accept that there is something it is like to be a bat that we cannot know while still holding it is a physical fact, beyond our representational reach.

Judgement: the knowledge argument is valid and intuitively powerful, but it is not decisive, because the ability and acquaintance replies offer credible ways to grant that Mary changes on release without conceding a new non-physical fact. Nagel rightly shows that physical descriptions leave out the first-person perspective, but this establishes an epistemic gap in our knowledge, not necessarily an ontological gap in what exists. Qualia constitute the deepest standing challenge to physicalism, but whether they refute it depends on the contested claim that knowing-what-it-is-like is genuine factual knowledge.