How likely is it that a subset of the 6 billion people that can pass a turing test aren't conscious? That they don't have subjective conscious, but are fooling those of us that do? I suspect the odds reasonably would be greater than zero -and perhaps significantly greater. This is the flip side of the argument "if a computer program or an upload can pass a turing test, then it's subjectively conscious". Perhaps some of the 'people' we thnk are subjectively conscious because they pass our current, informal turing tests are not.
Note: 4/27/08 I just corrected the wording in the title and post to correct a typo that's been in this post for about 6 months. Of course I meant "that can pass a turing test aren't conscious", not "are turing machines". This was caught early in the comments, and I think the rest of the post made it clear what I meant, so I was in no rush to correct it.