Knowledge Argument Mary Room

Overview of the Knowledge Argument

The Knowledge Argument, often referred to through the thought experiment of Mary’s Room, is a central debate in contemporary philosophy of mind. Introduced by Frank Jackson in the early 1980s, it challenges physicalism—the view that all facts about the world, including mental facts, are ultimately physical facts.

Jackson imagines Mary, a brilliant color scientist confined for her entire life to a black-and-white room. Despite never having had a color experience, Mary learns all there is to know about the neurophysiology, optics, and physics of color vision. She knows every physical fact about how normal human beings see colors.

The crucial question is: When Mary leaves the room and sees red for the first time, does she learn something new? Jackson claims that she does—she learns what it is like to see red. If true, this suggests that there are non-physical facts (facts about subjective experience, or qualia) that are not captured by the totality of physical information, thereby casting doubt on physicalism.

Structure and Aims

The Mary thought experiment is designed as an argument by counterexample against the completeness of physicalism.

Key elements include:

• Mary’s knowledge condition:
  Mary knows all the physical facts about color vision. This is usually taken to include facts about brain processes, wavelengths, functional roles, and all scientific laws relevant to color perception.

• Mary’s experiential deficit:
  Mary has never experienced color herself due to her confinement to a monochrome environment (and, in some versions, color-filtered media).

• The transition:
  Upon release, Mary has her first color experience—for instance, seeing a red tomato.

The argument can be summarized:

1. Before leaving the room, Mary knows all the physical facts about color vision.
2. Upon seeing red for the first time, Mary learns something new—namely, what it is like to see red.
3. Learning something new implies that there are facts she did not previously know.
4. Therefore, there are facts about color experience (facts about qualia) that are not physical facts.
5. Hence, physicalism, as the thesis that all facts are physical facts, is incomplete or false.

The aim is not simply to highlight a psychological surprise, but to argue that first-person phenomenal knowledge—knowledge of what experiences are like—cannot be reduced to, or fully captured by, third-person physical descriptions.

Major Responses and Criticisms

Because the Knowledge Argument threatens physicalism, it has generated multiple sophisticated responses. These do not generally deny the story, but reinterpret what Mary gains when she leaves the room.

1. The Ability Hypothesis

David Lewis and Laurence Nemirow defend what is often called the Ability Hypothesis. They argue that Mary does not acquire new propositional knowledge (knowledge-that), but instead gains new abilities:

• the ability to recognize red experiences,
• the ability to remember and imagine colors,
• the ability to identify and classify her experiences in new ways.

On this view, Mary knew all the facts while in the room; her subsequent learning is a matter of acquiring know-how, not discovering new non-physical facts. Thus, physicalism can be preserved by distinguishing kinds of knowledge.

Critics of the Ability Hypothesis argue that Mary seems to learn a truth about the world—“So this is what red looks like”—and that this looks more like factual knowledge than mere skill acquisition.

2. The New-Concepts / Old-Facts Response

Another family of responses maintains that Mary gains new concepts rather than access to new facts. She always had access, in principle, to all the physical facts, but lacked the phenomenal concepts needed to represent some of them from the first-person perspective.

According to this Phenomenal Concepts Strategy:

• Mary acquires a new way of thinking about physical facts she already knew.
• Her new color experience allows her to deploy phenomenal concepts like “this kind of reddish experience,” without adding non-physical properties to her ontology.

Supporters claim this explains the intuition of discovery while keeping physicalism intact; the world does not gain new facts, but Mary gains a new conceptual scheme.

Opponents counter that if Mary’s prior “complete physical knowledge” left her unable to know what red is like, then something seems missing from any purely physical account, regardless of how it is conceptualized.

3. Denying the Intuition: No New Knowledge

Some philosophers reject the central intuition that Mary learns anything genuinely new. On this view, if Mary really did know all physical facts, and if physicalism is true, then she could, by imaginative reasoning, know what red would be like before seeing it.

This response often involves:

• questioning the coherence of claiming that Mary’s “physical knowledge” is truly complete, and
• suggesting that if such knowledge were possible, it would include perfect imaginative and representational capacities.

Critics argue that this move is dialectically costly because it clashes with strong and widespread intuitions about the gap between objective description and subjective experience.

4. Jackson’s Own Retraction

Interestingly, Frank Jackson later abandoned the anti-physicalist conclusion he originally drew from Mary’s Room. He came to endorse a form of physicalism, interpreting the argument as highlighting the complexity of representational content and the distinctive nature of phenomenal concepts, rather than the existence of non-physical properties.

This retraction has not ended debate, but it has influenced many physicalists to treat the Knowledge Argument as a problem of explanation and representation, rather than straightforward refutation of physicalism.

Philosophical Significance

Mary’s Room has become a canonical case in discussions of:

• Qualia: the subjective, “what-it-is-like” aspects of experience.
• Epistemic gaps vs. ontological gaps: whether the gap between physical description and phenomenal knowledge signals a genuine gap in being (non-physical properties) or merely in knowing (different modes of access to the same physical reality).
• Consciousness and reduction: whether conscious experience can, in principle, be reduced to or explained by physical science.
• Types of knowledge: distinctions between propositional knowledge, ability knowledge, and knowledge by acquaintance.

Proponents of the Knowledge Argument see it as strong evidence that conscious experience cannot be fully captured by physicalist theories, often linking it to property dualism or other non-reductive views of mind. Critics view it as a puzzle about epistemology and concepts, arguing that physicalism remains tenable once these distinctions are carefully drawn.

Regardless of which response one favors, the Mary case remains a central and widely discussed thought experiment, shaping how philosophers articulate the relationship between mind, brain, and experience. It continues to serve as a focal point for testing and refining theories about consciousness, representation, and the limits of physical explanation.