Scholastic apriorism vs experimental reasoning:
"Science in humbling our pride, proportionately increases our power.
[Apriorism] borrows from some irrational source, such as revelation, tradition, a convention or an arbitrary authority. The more modest experimenter, on the other hand, states an idea as a question... which, moment by moment, he confronts with reality by means of experiment. He advances, thus, from partial to more general truths, but without ever daring to assert that he has grasped the absolute truth.
One must doubt... an a priori certainty."
-excerpt from physiologist Claude Bernard's An introduction to the study of Experimental Medicine, 1927