What Mary Didn’t Know

Exam results

Grade Distribution

Statistics Mean: 66.95 Median: 69 Mode: 74

The knowledge argument

Mary Brilliant scientist. Locked in a room with nothing red-colored since birth. Has never seen her own blood or anything else that’s red. Knows everything about color science and brain science.

“Real Life” Mary There’s a real vision scientist who can’t see colors: Knut Nordby. Read his story here: http://consc.net/misc/achromat.html

The Knowledge Argument Mary has all the physical information concerning human color vision before her release. But there is some information about human color vision that she does not have before her release. Therefore, not all information is physical information.

Horgan’s Distinction ‘Physical information’ can mean one of two things: X is [explicit] physical information = X is information expressed in the language of physics. X is [ontological] physical information = X is information about something that is completely made out of physical things.

Example ‘This is water’ is ontological physical information, because water is completely made out of physical stuff. But ‘this is water’ is not explicit physical information, because physics talks about “hydrogen” and “oxygen,” not “water.”

The Explicit Knowledge Argument #1 Mary has all the explicit physical information concerning human color vision before her release. But there is some information about human color vision that she does not have before her release. Therefore, not all information is explicit physical information.

#1 Good argument, but who cares? We already know that not all information is explicit physical information (for example info about “water”).

The Explicit Knowledge Argument #2 Mary has all the explicit physical information concerning human color vision before her release. But there is some information about human color vision that she does not have before her release. Therefore, not all information is ontological physical information.

Bad argument!

Analogy Distinguish two kinds of information about grades: X is [English-name] grade information = X is information about grades expressed using students’ English names. X is [ontological] grade information = X is information about grades.

The Explicit Knowledge Argument #2 Michael has all the English-name grade information. But there is some grade information Michael does not have. Therefore, not all grade information is ontological grade information.

Bad Argument! This is a bad argument. It’s possible that I know everyone’s grades, even though I don’t know everyone’s grades if they are stated with students’ English names.

The Explicit Knowledge Argument #3 Mary has all the ontological physical information concerning human color vision before her release. But there is some information about human color vision that she does not have before her release. Therefore, not all information is ontological physical information.

The ability hypothesis

Three Types of Knowing I know Jason Stanley. I know that Jason Stanley is a philosopher at Yale University. I know how to tickle Jason Stanley.

Knowing How vs. Knowing That Most philosophers think that knowing how to do something is not the same as knowing that _____. Where you can fill in the ______ with anything.

Knowing How vs. Knowing That Knowing that P is “propositional knowledge.” Knowing how to A is “practical knowledge.” A difference in propositional knowledge reflects a difference in the facts. But a difference in practical knowledge only represents a difference in one’s own skills.

Knowing How vs. Knowing That

Lewis and the Ability Hypothesis “Knowing what it is like is the possession of abilities: abilities to recognize, abilities to imagine, abilities to predict one's behavior by imaginative experiments.” – David Lewis, 1983

The Ability Response Mary learns how to do something new. She does not learn any new proposition. So there’s no reason to think there are additional non-physical facts.

Ability to Imagine But does Mary really only gain an ability, like the ability to imagine something? Suppose Mary can’t imagine anything, she can only experience what happens and think about her actual experience. Can’t she still know what it’s like to see red, and that this is what George experiences when he sees red?

Ability to Recognize Many color-blind individuals don’t know that they’re color-blind. They can still recognize different colors using context cues. We still want to say that they do not know what it’s like to see red.

Phenomenal concepts

Modes of Presentation The same facts can be presented in different ways: John Woo made Hard Boiled. Wu Yu-Sheng made Hard Boiled. Sometimes we know a fact presented one way, but don’t know the same fact presented a different way.

New Proposition/ Old Fact A common response to the knowledge argument is to say that Mary learns a new proposition, but that this proposition is just a different presentation of a fact she already new before leaving the room.

Example For example, if I learn German, I learn a new way to represent the fact that snow is white (“Der schnee ist weis”), but I don’t learn a new fact (I already know that snow is white).

Phenomenal Concepts So the general response to the knowledge argument goes: Mary learns a new way to represent the fact that roses are red. She already knew that fact, but now she has a new “language” to represent it in: the language of phenomenal concepts.

The Language of Thought Fodor (1975) argues that learning a language requires already being able to represent what’s learned. Thus, there must be able to represent everything we can learn to say before we learn to say it. The “language” that we use before we learn language is called the language of thought.

LOT and Word Learning To learn English ‘cow’ (for English-as-a-first-language-speakers) requires: hypothesizing that ‘cow’ means COW testing that hypothesis against the linguistic evidence and having the hypothesis confirmed by the evidence.

LOT vs. The Knowledge Argument So here’s the picture: the mind has a particular way of representing redness – the LOT word “RED.” The only way that word shows up in your thoughts is if light of a certain wavelength stimulates your L-cones. What Mary learns is how to represent redness with RED.