You unexpectedly find yourself sitting in a windowless room across from a gray-haired gentleman. You didn't wake up there; you were walking down the street and cut to camera two, a white windowless room with a table and two chairs. After a moment, the gentleman speaks:
"You are dead, killed instantly by a small meteorite. Incidentally," he smirks, "you have lost Pascal's Wager. You may 'cross-over' once you can accept that you are dead. I am here to help in that endeavor and can present any evidence you desire."
You, being a stone-cold rationalist, will only reach this conclusion on the basis of solid evidence. He, being extremely ethical, will neither present false evidence nor attempt to undermine your rationality. What can he do to convince you that you have died?
I suspect there is nothing he could say or do to convince you of this. Rather, for any sufficiently "final" definition of physical death, there's no way he can demonstrate that you have somehow come out the other side. That's my wager: there is no sound way to convince someone, even while in the afterlife, that there is such a thing; thus, we should never believe in an afterlife knowing that we could never accept it even if actually there.
Am I wrong? Has this been proposed before? Is there any thing which, while actually true, could never be demonstrated in this manner?
I think that, if correct, this may point to a special class of untruths. Sort of... Bayesian contradictions, things which could never be sufficiently demonstrated.
Naturally, lukeprog's earlier post has me thinking on religious lines.
Well, one question is to define specifically what death he wishes me to accept before I leave the room. So when he says "You are dead." And I ask "Which kinds of dead am I?" If he says:
"You are information theoretically dead. You're also brain dead and clinically dead." then that leads to an entirely different kind of much more confusing discussion. (What exactly is he arguing with? If the answer is my soul, what is the nature of my soul? An 'Elan Vital' style answer doesn't clarify anything unless learning to accept an 'Elan Vital' is the point of locking me into a room, in which case that will cause me to consider the room in an entirely different light.)
"You are information theoretically alive, but you are brain dead and clinically dead." (Your pattern of experiences has been teleported by some means to a locked room. You can resume experiencing things that are not the locked room when yoou have seen sufficient evidence that you accept you are brain dead and clinically dead.)
Or perhaps, "You're information theoretically dead, brain dead, but clinically alive." (You are a comatose vegetable with irreversible brain damage.)
Or perhaps even, "You're information theoretically dead, brain alive, but clinically dead." (It might be more accurate to say you've suffered massive trauma, exploding your body and head and throwing your intact brain from it's body. There is no state of affairs where you don't die, but technically your brain is still oxygenated for a few seconds and is producing a few last gasp hallucinations.)
Also, another question is "Do I even WANT to 'cross-over?' " I mean, he says he is here to help me in that endeavor, but I don't know if every rationalist would even necessarily be endeavoring to do that. Particularly not if told that by someone who also told them they lost Pascal's wager. If I HAVE been transported into something similar to the Christian afterlife, accepting what might be the Devil's implied axioms without double checking them seems likely to be a mistake.
Another pertinent question is "Which religion on earth is this situation in this afterlife closest to and how close is it?"
If the answer is "Catholicism. Mostly accurate with a few details wrong." That may also lead to an entirely different approach from "Atheism. And really, not even Atheism is that close."
I also want to note something else about your original post:
Gödel's first incompleteness theorem talks about things that relate to this concept. See http://en.wikipedia.org/wiki/G%C3%B6del%27s_incompleteness_theorems for details.