Every work of science great enough to be well remembered for a few generations affords some exemplification of the defective state of the art of reasoning of the time when it was written; and each chief step in science has been a lesson in logic.
Charles Sanders PeirceThe percept is the reality. It is not in propositional form. But the most immediate judgment concerning it is abstract. It is therefore essentially unlike the reality, although it must be accepted as true to that reality. Its truth consists in the fact that it is impossible to correct it, and in the fact that it only professes to consider one aspect of the percept.
Charles Sanders PeirceThe one [the logician] studies the science of drawing conclusions, the other [the mathematician] the science which draws necessary conclusions.
Charles Sanders PeirceWe should chiefly depend not upon that department of the soul which is most superficial and fallible (our reason), but upon that department that is deep and sure, which is instinct.
Charles Sanders Peirce