I’ll meet Sam’s challenge. Here’s something crazy that I believe in.
I believe it is impossible to have false beliefs. That is, I believe I cannot be wrong, though you can. I believe you believe that about yourself, and that you are right. This is, straightforwardly, a problem of the essential indexical. This time, however, the problem is not about content itself, but about the epistemic character of that content.
I presuppose that human psychology works in order to figure out the world. Having beliefs is a central part of this feat. I also presuppose that Pierce is right and that believing something is reaching a mental state of easiness, calm, and stability. Belief states are opposed to states of doubt and uncertainty. These ones force the organism to come up with some belief (i.e., to come up with some story that gets the easiness back, leaving out the worries and doubts). Thus, believing something is essentially a matter of having a story about the world, a matter of having figured out something such that easiness and tranquility governs the mind.
That’s why I can’t have false beliefs. Ascribing false beliefs is literally the same as doubting. When a false belief is ascribed, ignorance is given. Thus, no story about the world is around to be believed. In a sense, ascribing false beliefs is ill defined. It is something more like taking beliefs out of some organism, rather than positing them. This is why I cannot have false beliefs, but you can. I can believe in something that contradicts your belief, and so I go on and ascribe a false belief to you. And you do pretty much the same thing. This makes a lot of sense. What doesn’t make any sense is to go on ascribing false beliefs to your self. Self-ascription of beliefs is never a matter of ascribing false beliefs. False beliefs are essentially a third person invention; and a very useful one.
This creates a problem about belief revision. If self-ascribed beliefs are essentially ascribed as true beliefs, then no one can self-ascribe false beliefs. Belief revision, however, is a matter of self-ascribing false beliefs. Then belief revision appears to be impossible. No one can possibly believe that p and at the same time believe that p is false. Belief revision is supposed to be a matter of getting rid of false beliefs; but we cannot have them to begin with.
It seems then, that no belief revision process is a process of self-knowledge. Rather, it looks more like belief revision inherently involves ‘two’ minds, at least two slices of the same space-time worm. It couldn’t be otherwise, because I can’t be wrong, although you always can. And this does not, and cannot, translate into "Eduardo can’t be wrong, although M always can." As I said before, this is another problem with the essential indexical.