If you are only skeptical, then no new ideas make it through to you. You become a crotchety old person convinced that nonsense is ruling the world. (There is, of course, much data to support you.) But every now and then, a new idea turns out to be on the mark, valid and wonderful. If you are too much in the habit of being skeptical about everything, you are going to miss or resent it, and either way you will be standing in the way of understanding and progress.
Carl SaganOne of the great commandments of science is, 'Mistrust arguments from authority'. (Scientists, being primates, and thus given to dominance hierarchies, of course do not always follow this commandment.)
Carl SaganThere are no forbidden questions in science, no matters too sensitive or delicate to be probed, no sacred truths.
Carl Sagan[Kepler] preferred the hard truth to his dearest illusions, and that is the heart of science.
Carl SaganWhat a splendid perspective contact with a profoundly different civilization might provide! In a cosmic setting vast and old beyond ordinary human understanding we are a little lonely, and we ponder the ultimate significance, if any, of our tiny but exquisite blue planet, the Earth.... In the deepest sense the search for extraterrestrial intelligence is a search for ourselves.
Carl SaganWhen a honeybee dies it releases a death pheromone, a characteristic odour that signals the survivors to remove it from the hive. The corpse is promptly pushed and tugged out of the hive. The death pheromone is oleic acid. What happens if a live bee is dabbed with a drop of oleic acid? Then no matter how strapping and vigourous it might be, it is carried kicking and screaming out of the hive.
Carl Sagan