On page 123 of The Conscious Mind (1996) Chalmers gave us his ‘basic argument’ against materialism.

(1)   In our world, there are conscious experiences.

(2)   There is a logically possible world physically identical to ours, in which the positive facts about consciousness in our world do not hold.

(3)   Therefore, facts about consciousness are further facts about our world, over and above the physical facts.

(4)   So materialism is false.

[The logically possible world he had in mind is, of course, a zombie world.]

Time has passed. That was 14 years ago.  His rich, and beautifully developed, line of thought has been studied by lots of smart and well-informed philosophers, many of whom, no doubt, disagreed with him. How well has his argument withstood the barrage?

For what it ‘s worth, I find premise (2) difficult to believe. I’m not at all sure that zombies are logically possible (i.e. ‘epistemically possible’.)

On the other hand, I find the story about Mary (p.103) quite persuasive. If she escapes from the black and white room, and, for the first time sees some red roses, she gains a kind of knowledge she didn’t have before. She learns something about a feature of the world she didn’t know before.

Somewhere in the book (I forget where) Chalmers moves from Mary to the zombies. I think his suggestion is, if you buy the Mary story you should regard the zombies as logically possible.

Perhaps I should, on the other hand…

As an additional worry, I am inclined to think that Scott Soames is right about Ambitious Two-Dimensionalism [see Reference and Description ch. 9]

To tell the truth, I would like to accept Chalmers’ argument. But (obviously) like Allan, I suffer from scruples.