Mind and body · Quiz question 4/35
Mary's Room (The Knowledge Argument)
Mary knows every physical fact about color. When she finally sees red, does she learn something new? Frank Jackson's knowledge argument and the physicalist replies.
Mary has spent her whole life in a black-and-white room, but she knows all the physics and neuroscience of color. One day she steps outside and sees a red apple for the first time.
In that moment, Mary learns something new.
Australian philosopher Frank Jackson introduced it in his 1982 paper "Epiphenomenal Qualia." Mary, a neuroscientist raised in a black-and-white room, learns every physical fact about color vision. If she learns something new when she steps out and sees red for the first time, then physical information isn't everything — so physicalism is false. That's the "knowledge argument." Fun fact: Jackson himself later changed his mind and accepted physicalism in the late 1990s.
If you agreed, you think conscious experience has something physical explanations don't capture — "what seeing red is like" (qualia). That points toward dualism or non-reductive views.
Physicalists answer in a few ways. David Lewis and Laurence Nemirow say Mary gains a new ability (to imagine and recognize red), not a new fact. Brian Loar and others say Mary grasps a fact she already knew under a new, phenomenal concept. Daniel Dennett argued that if Mary truly knew every physical fact, she wouldn't even be surprised by red — we just can't properly imagine that situation.
Even knowing every physical fact leaves out what experience is like. So physicalism is incomplete.
Key names: Jackson (1982), David Chalmers, Thomas NagelWhat Mary gains is a new ability, or a new way of grasping the same fact.
Key names: David Lewis, Laurence Nemirow, Brian LoarTake "knows every physical fact" seriously and Mary isn't surprised at all.
Key names: Daniel Dennett, Paul Churchland