Preliminary For our purposes, Physicalism = Materialism. Jackson is a “qualia freak”; he believes qualia are non-physical.

Mary and The Knowledge Argument Mary learns something new when she finally sees colored things. But prior to that time, Mary knew all of the physical facts about color experience. Therefore, what she learns when she finally sees color isn’t a physical fact. Therefore, there are nonphysical facts. Therefore, physicalism is false.

What will the physicalist say? Here’s one possibility: Seeing red is a certain physical state, R1. Knowing what it is like to see red is a certain physical state that typically results from R1—call this R2. Knowing all about the physical process involved in color vision involves a bunch of other states R3...Rn. Why should we expect that being in R3....Rn would cause R1 or R2?

The Knowledge argument restated? Mary was in R3...Rn (but not R1 or R2) which represent, among other things, facts about R1 and R2. Then Mary went outside and was in R2, caused by her being in R1. So...? Why should physical states whose contents are facts about R1 or R2 have any special power to cause physical state R2?

Diagnosis Jackson’s reasoning was airtight, though. Where does he go wrong in his assumptions? Jackson has a choice: 1. He can say that knowing all of the physical facts about color includes being in states R1 and R2 In which case Mary doesn’t know everything physical about color vision when in the room, and he has mis-described the example.

Or 2. Jackson can say that Mary, as he described here, knew everything physical to know about vision, explicitly excluding being in R1 and R2 from the original description; in which case, Mary’s “learning something new” (that is, her brain going into R1, then R2) doesn’t count against physicalism. On this interpretation, Jackson has constrained the set of physical facts, excluding certain states of the brain that are caused by interacting with colored things.

But what does Mary learn!? Possibility: She learns new facts about physical events in her own biography: “I was in R1” (which is partly expressed by the activation of R2). This is the content of R2. Obviously, it cannot be induced merely by knowing the facts about color vision, even if it is physical.

Physicalism and what it’s like to be a bat A human cannot know what it is like to echolocate. Humans can know all of the physical facts about echolocation. So, the physical facts leave something out. So, physicalism is false. Similar diagnosis to Mary’s case

The modal argument and zombies It is possible for there to exist a perfect physical duplicate of an actual human being that lacks conscious experience. Therefore, physicalism is false (the actual person must have a nonphysical aspect that’s being “left out”).