4. The conception of human knowledge as falling necessarily short of absolute truth and certainty, but capable of attaining (in Locke’s words) such certainty as our condition needs; or (as Hume puts it) that reason is incapable of dispelling the clouds of doubt, but that Nature herself (our human nature) suffices for that purpose and lays upon us in our practical life an absolute necessity to live and talk and act like other people.
