To whom it may concern:
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.
(After the critical success of part II, and the strong box office sales of part III in spite of mixed reviews, will part IV finally see the June Open Thread jump the shark?)
I don't have Searle's book, and may be missing some relevant context. Does Searle believe normal humans with unmodified brains can consciously affect their external behavior?
If yes, then there's a simple solution to this fear: do the experiment he describes, and then gradually return the test subject to his original, all-biological condition. Ask him to describe his experience. If he reports (now that he's free of non-biological computing substrate) that he actually lost his sight and then regained it, then we'll know Searle is right, and we won't upload. Nothing for Searle to fear.
But if, as I gather, Searle believes that our "consciousness" only experiences things and is never a cause of external behavior, then this is subject to the same criticism as Searle's support of zombies.
Namely: if Searle is right, then the reason he is giving us this warning isn't because he is conscious. Maybe in fact his consciousness is screaming inside his head, knowing that his thesis is false, but is unable to stop him from publishing his books. Maybe his consciousness is already blind, and has been blind from birth due to a rare developmental accident, and it doesn't know what words he types in his books at all. Why should we listen to him, if his words about conscious experience are not caused by conscious experience?
Searle thinks that consciousness does cause behavior. In the scary story, the normal cause of behavior is supplanted, causing the outward appearance of normality. Thus, it's not that consciousness doesn't affect things, but just that its effects can be mimicked.
Nisan's criticism is devastating, and has the advantage of not requiring technological marvels to assess. I do like the elegance of your simple solution, though.