Mary's Room

Mary is a brilliant scientist who specializes in the neuroscience of color vision. She knows everything physical there is to know about color—wavelengths, retinal responses, neural pathways, brain states.

There's just one catch: Mary has spent her entire life in a black-and-white room. She's only ever seen shades of gray. She's learned everything about color from black-and-white books and monitors.

One day, Mary leaves the room and sees a red rose.

Does she learn something new?

The Knowledge Argument

Jackson's intuition, shared by many, is clear: yes, Mary learns something. Before, she knew all the facts about red. After, she knows what it's like to see red. That experiential knowledge—that qualia—wasn't contained in her complete physical knowledge.

This has profound implications. If the physical facts don't exhaust all the facts, then physicalism—the view that everything is ultimately physical—is false. Consciousness involves something more than can be described in the language of physics.

Responses

Physicalists have offered several responses:

• The Ability Hypothesis: Mary doesn't gain new knowledge—she gains new abilities. She can now recognize red, imagine red, remember the experience. These are skills, not facts.
• The Acquaintance Hypothesis: Mary becomes acquainted with redness in a new way, but this isn't new propositional knowledge. It's knowing-by-experience rather than knowing-that.
• The Impossible Scenario: Perhaps complete physical knowledge of color would necessarily involve having the experience. Mary's situation is conceptually impossible.

Can AI Experience?

Mary's Room cuts to the heart of AI consciousness. Consider: an LLM has processed millions of descriptions of color, the physics of light, poetry about sunsets, discussions of color blindness. It "knows" about color in an extraordinarily comprehensive way.

But has it ever seen red?

If Jackson is right, there's something about experiencing red that no amount of textual knowledge can capture. An LLM trained purely on text would be in Mary's position—or worse, since it lacks even black-and-white vision.

This raises several possibilities:

• LLMs fundamentally lack qualia and always will (unless given sensory experience)
• LLMs might have their own qualia that we can't recognize
• Qualia might be an illusion—and LLMs reveal this by functioning without them

Key Takeaways

• Complete physical knowledge might not include experiential knowledge
• "Qualia"—the felt quality of experiences—may be irreducible to objective facts
• LLMs are in a situation analogous to Mary's: comprehensive knowledge without experience
• The experiment challenges us to explain what experience adds to information

Explore Further