"The question is how to arrive at your opinions and not what your opinions are. The thing in which we believe is the supremacy of reason. If reason should lead you to orthodox conclusions, well and good; you are still a Rationalist. To my mind the essential thing is that one should base one's arguments upon the kind of grounds that are accepted in science, and one should not regard anything that one accepts as quite certain, but only as probable in a greater or a less degree. Not to be absolutely certain is, I think, one of the essential things in rationality."