"No serious thought can be constructed without assumptions, but recognizing them - in our own thinking as well as in others is vital if we are to avoid falling into serious error. Assumptions are beliefs; if they were proven they would not be assumptions. And they are beliefs so taken for granted that it is not deemed necessary to prove them. That makes them doubly seductive: first, because the careless or untrained are misled into accepting conclusions without recognizing their shaky foundation of unstated beliefs; and second, the very fact that the most dubious beliefs are so taken for granted by experts lends an aura of verisimilitude that beguiles the overly respectful into accepting them without question."
"Assumptions, in fact, are more powerful than assertions, because they bypass the critical faculty and thereby create prejudice.... The simple act of listening to an argument is almost enough to engage it.... That bypassed assumption is the pocket of enemy soldiers that was ignored in an effort to engage the main body of the adversary, and it lies in wait to strike from the rear. The false assumption is additionally beguiling because it often appeals to one of the worst instincts - the desire to be fashionable or at least to avoid being associated with the unfashionable or unpopular." (Herbert Schlossberg, Idols For Destructions. )