Nice one. I simply love paradoxes.
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But still: you can prove anything if you believe in it. It depends on the system "inside" which you prove. E.g. mathematics: I can prove that 7 + 7 = 2 (riddle for you). And I can even prove it INSIDE mathematics. In fact, I can prove anything in mathematics that is not in antagonism with definitions. And definitions are what? They are something we just believe in.
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