The use of violence is justified only under a tyranny which makes reforms without violence impossible, and should have only one aim, that is, to bring about a state of affairs which makes reforms without violence possible.
Karl PopperNo rational argument will have a rational effect on a man who does not want to adopt a rational attitude.
Karl PopperEvolution is not a fact. Evolution doesn't even qualify as a theory or as a hypothesis. It is a metaphysical research program, and it is not really testable science.
Karl PopperCriticism of my alleged views was widespread and highly successful. I have yet to meet a criticism of my views.
Karl PopperThere is an almost universal tendency, perhaps an inborn tendency, to suspect the good faith of a man who holds opinions that differ from our own opinions. It obviously endangers the freedom and the objectivity of our discussion if we attack a person instead of attacking an opinion or, more precisely, a theory.
Karl Popper