Well... many posts after... im here again.
You are right, we (still) cant prove that we live (or dont) into a Matrix, or into some alien simulation, or whatever. Soon i will arrive there. But first:
Somebody mentioned self-consistency of the universe... well... i think its not a very good way for testing it... as we humans have a very bad tendence to close our eyes to what we cant understand, or dont want to see... for example, take the things called "paranormal", like psychokinesis, telepathy and such... or the so-called "miracles", present in every religion... well, most scientists will say that this things doenst even exist, so they wont bother to search and see if they are real or not. And it happens with everybody. When we see a thing that dont fit our view of world, we simply discard it as "illusion", "hallucination", and so. Doing this, we keep our world consistent, even if the proofs of its unconsistency were right before our eyes.

And we arrive at the matrix question... well... i dont know if we live in a computer-based simulation, but im sure (its my own belief, mind you) that we call "reality" is only a product of our minds, not a "real" thing. What we see is not the world itself, but the electromagnetic waves recieved by our eyes, and interpreted by our brain. So, we are very far from the "reality" itself. Its not my idea, it comes from long long ago... Buddha already said that the world is a illusion, Plato talked about its cave, don Juan Matus also said the same... and, interestingly enough, some days ago a member of cann.com had an very interesting experience, where he supposedly reached the nirvana and did see the "real" nature of the things... and his description is very similar to many other descriptions of this kind of experience, and thats why i really believe that he really did see the "true" nature of reality.
If you wish to read it, look at:
http://boards.cannabis.com/spiritual...iscussion.html

BTW, i know the discussion of the nature of the reality is endless, as well as the discussion of the nature of the past, as well as most (if not all) phylosophical discussions... anyway... if its our duty to discuss, then lets do it!