Exactly -- that's the kind of thing I had in mind: the player has to navigate through rationalizations and be able to throw out unreliable claims against bold attempts to protect it from being proven wrong.
So is this game idea something feasible and which meets your criteria?
I think so, actually. When I start implementation, I'll probably use an Interactive Fiction engine as another person on this thread suggested, because (a) it makes implementation a lot easier and (b) I've enjoyed a lot of IF but I haven't ever made one of my own. That would imply removing a fair amount of the RPG-ness in your original suggestion, but the basic ideas would still stand. I'm also considering changing the setting to make it an alien world which just happens to be very much like 17th century England except filled with humorous Rubber Forehead A...
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.