CFS,

1. I think you're saying that Dr. Sampson has concluded CFS is psychological. I read him as expressing a bias or an expectation that CFS will, in most cases, be caused by psychological factors.

2. The problem with an unsconcious cause is non-falsifiability. Yet we know unconscious processes exist. So when no physical etiology is found, we're left with the possibility some unknown physical process accounts for the problem, or some unconscious process may be causing the problem.

3. Sometimes we can prove an emotional factor is associated with the symptoms. But sometimes we later discover a physical cause also. The reverse can be true, too.

4. I know of no good way to construct a "we don't know" category that does not convey a sense that unconscious factors may be involved.

5. One day this argument will be moot, as mind will reduce to body. But that's just my bias, not an assertion of fact.