Keeping an open mind on the mind-body problem, part 1

I've been thinking about the mind-body problem. One oddity about the problem is that, as Descartes famously recognized, the very act of "thinking" about it provides you with evidence that ties directly into the problem -- namely evidence of the fact that you have mental states.

But Thomas Nagel says (in his essay "Why We Are Not Computers," from Other Minds):

The power of Descartes's intuitive argument is considerable, but dualism of either kind [substance dualism or property dualism] is now a rare view among philosophers, most of whom accept some kind of materialism. They believe that everything there is and everything that happens in the world must be capable of description by physical science.

That last sentence is deeply disturbing to me. There's an obvious problem and a less obvious problem with the assumption that the mind-body problem can be solved purely through physical science.

The obvious problem is: why should we assume we can know everything?

When I was a little kid, I would tell people, "I know everything, and you know neverything." Clearly I had an instinctive desire to "know everything," and I'm sure the feeling is common. But as I say, I was a kid. You're supposed to outgrow that. I don't see the point in doing philosophy if you don't acknowledge there might be things you just can't know about the world. Maybe most philosophers do assume science can explain everything, but if so, then most philosophers are being childish.

The less obvious problem is (again quoting Nagel from the same book):

all materialist theories deny the reality of the mind, but most of them disguise the fact (from themselves as well as from others) by identifying the mind with something else.

UPDATE: Continued here.