Lecture 4 Summary

1 - Mary knows all the physical truths about seeing red without ever having seen red.

2 - Mary comes to know something new about seeing red when she leaves the room - she learns what it’s like to see red.

3 - Therefore, not all the truths about seeing red are physical.

Physicalism is refuted only if it’s construed as this thesis:

All the truths about every kind of conscious experience are truths about kinds of physical state.

Recall that a truth is an object of propositional knowledge. So on this construal of Physicalism, it’s the thesis that once one knows everything about conscious experiencing that can be learnt in science lessons, one cannot extend one’s knowledge of it. But Mary seems to do so. Therefore Physicalism is false.

But consider a world with 2 gods. Each knows all the physical truths, but neither knows which god He is. Each can advance His knowledge by coming to know which god He is. Nonetheless, each state of the world is a physical state. So we ought to distinguish:

- Each state of this world is physical - True.
- Each truth about this world is physical - False (given what ‘truth‘ means for us).

Similarly, perhaps each kind of conscious experience is really a kind of physical state, despite not all truths about conscious experiencing being physical truths. Mary may extend her knowledge by seeing the rose - just as our imagined god might extend His knowledge. Perhaps her new experience enables her to have new knowledge because it gives her new concepts. (Now she can think about red in terms of what it’s like to see.) The knowledge argument might undermine the above construal of Physicalism, but it doesn’t undermine this more interesting construal:

All kinds of conscious experience are kinds of physical state.