Fine, with our current knowledge knowledge of physics the Alien trick would be almost impossible. But shouldn't we rather estimate the probability that future physicists would discover something radically new? And isn't this proposition significantly harder to estimate? Making your secondary evidence less strong?
"You asked elsewhere why you are getting downvotes, and the brief answer is that you are dramatically over-weighing the strength of the relevant evidence."
That's why I said that my belief was not of much interest :) The topic of this thread really shouldn't be about my belief. It would be just as interesting as discussing the aesthetic merits of my left little toe.
Beliefs don't exist outside of people (and other animals). If we want to talk about beliefs, we have to point inside at least one person's head.
Recently I've been struck with a belief in Aliens being present on this Earth. It happened after I watched this documenary (and subsequently several others). My feeling of belief is not particular interesting in itself - I could be lunatic or otherwise psychological dysfunctional. What I'm interested in knowing is to what extend other people, who consider themselves rationalists, feel belief in the existence of aliens on this earth, after watching this documentary. Is anyone willing to try and watch it and then report back?
Another question arising in this matter is how to treat evidence of extraordinary things. Should one require 'extraordinary evidence for extraordinary claims'? I somehow feel that this notion is misguided - it discriminates evidence prior to observation. That is not the right time to start discriminating. At most we should ascribe a prior probability of zero and then do some Bayesian updating to get a posterior. Hmm, if no one has seen a black swan and some bayesian thinking person then sees a black swan a) in the distance or b) up front, what will his a posterior probability of the existence of black swans then be?