After leaving the black-and-white room, Mary says 'I now know something I didn't know before.' A physicalist defending the ability hypothesis responds. Which response best captures their position?
AMary is mistaken — if she truly had complete physical knowledge before, she cannot have learned anything new
BMary gained a new physical fact about color vision that her earlier knowledge was incomplete without
CMary didn't gain propositional knowledge of a new fact — she gained the ability to recognize, remember, and imagine red experiences, which is know-how rather than knowledge-that
DMary confirms dualism — her new knowledge is evidence of a non-physical aspect of consciousness
The ability hypothesis, developed by Nemirow and Lewis, accepts that something changed for Mary upon release but denies it was propositional knowledge of a new fact. What Mary gained was a cluster of abilities: to recognize red when she sees it, to remember the experience, to imagine it. This is know-how rather than knowledge-that — more like learning to ride a bike than learning a new theorem. The dualist conclusion is blocked because no new fact was learned; the physical facts were always complete.
Question 2 Multiple Choice
What is the conclusion of Jackson's knowledge argument as originally presented?
APhysicalism is false, because Mary's new knowledge upon seeing red reveals facts about consciousness not contained in any complete physical description
BConsciousness is an illusion, since Mary already knew all physical facts about color vision before release
CMary's case shows that color vision is too complex to be fully explained by current neuroscience
DPhenomenal knowledge and physical knowledge are identical once the right conceptual framework is applied
Jackson's argument has three steps: (1) Mary has complete physical knowledge of color vision before her release; (2) she learns something new when she sees red; (3) therefore not all facts are physical facts — physicalism is false. The argument targets physicalism directly, using the thought experiment to show that first-person phenomenal knowledge cannot be derived from third-person physical descriptions no matter how complete those descriptions are.
Question 3 True / False
Frank Jackson continued to defend the anti-physicalist conclusion of the knowledge argument throughout his career, maintaining that Mary's new knowledge proves consciousness involves non-physical facts.
TTrue
FFalse
Answer: False
Jackson later retracted the anti-physicalist conclusion, arguing that Mary learns only a new mode of presentation of facts she already knew — a new way of conceptually accessing the same physical states. Despite inventing the thought experiment, he did not remain committed to its original dualist implication. The argument continues to be influential not because Jackson endorses its conclusion but because it isolates the explanatory gap in a vivid way that physicalists must answer.
Question 4 True / False
The knowledge argument supports the claim that, even granting a complete physical description of the brain, there remain facts about phenomenal experience that are not derivable from that description.
TTrue
FFalse
Answer: True
This is the argument's core claim. Mary's completeness of physical knowledge is stipulated — she knows everything there is to know physically about color vision. The argument then shows (or attempts to show) that she still lacks something: knowledge of what red looks like from the inside. If the argument succeeds, phenomenal facts are not entailed by physical facts, which is precisely what physicalism denies. Whether or not one accepts the conclusion, the argument correctly identifies the explanatory gap that any complete physicalist account must close.
Question 5 Short Answer
What is the 'explanatory gap,' and why does the knowledge argument illustrate it even for someone who ultimately rejects the anti-physicalist conclusion?
Think about your answer, then reveal below.
Model answer: The explanatory gap is the apparent inability to derive facts about subjective experience — what it feels like to see red, feel pain, or taste coffee — from any purely physical description, however complete. Even if you accept the ability hypothesis (Mary gains know-how, not new facts), you still need to explain why phenomenal concepts give a different 'grip' on physical states than scientific descriptions do. The gap between neural state N and the feeling of redness doesn't disappear by relabeling it. The knowledge argument makes this vivid by asking: if all physical facts were known, what would still be missing? The answer — the felt quality of experience — is precisely what any physicalist account must explain.
The explanatory gap was named by Joseph Levine. It describes the puzzle that physical explanations, however detailed, don't seem to close the loop to explain why there is subjective experience at all, or why the experience has the particular quality it does. The knowledge argument dramatizes this gap by stipulating that all physical knowledge is in hand and asking whether anything remains.