In recent years it has become apparent that “the mind-body problem” is not one problem but many, and that some of these problems have become amenable to scientific research (for a review, see Velmans 1996c). However, some of the ancient puzzles persist. Those discussed in Solms's thoughtful paper are among the most perplexing. What is consciousness? How does human consciousness fit into the complex dynamic of unconscious mental life? How could brain states produce subjective conscious experiences? And how could conscious experiences influence the activity of brains?

These problems interconnect. If conscious experiences are nothing more than brain states (as claimed by the “physicalists” within philosophy of mind), then their causal interaction with brain states presents no philosophical puzzle. It is hardly surprising that this position is popular