Note 453 — Chapter IX · CHRISTENDOM IN THE MIDDLE AGES

Only less original is Occam, who at Paris came much under Marsiglio’s influence. His philosophic doctrines apparently derive from Pierre Aureol (Petrus Aureolus, d. 1321), who with remarkable clearness and emphasis rejected both Realism and the doctrine that what the mind perceives are not realities, but formæ speculares. Pierre it was who first enounced the Law of Parsimony in philosophy and science—that causes are not to be multiplied beyond mental necessity—which is specially associated with the name of Occam.453 Both anticipated modern criticism454 alike of the Platonic and the Aristotelian philosophy; and Occam in particular drew so decided a line between the province of reason and that of faith that there can be little doubt on which side his allegiance lay.455 His dialectic is for its time as remarkable as is that of Hume, four centuries later. The most eminent orthodox thinker of the preceding century had been the Franciscan John Duns Scotus (1265 or 1274–1308), who, after teaching great crowds of students at Oxford, was transferred in 1304 to Paris, and in 1308 to Cologne, where he died. A Realist in his philosophy, Duns Scotus opposed the Aristotelian scholasticism, and in particular criticized Thomas Aquinas as having unduly subordinated faith and practice to speculation and theory. The number of matters of faith which Thomas had held to be demonstrable by reason, accordingly, was by Duns Scotus much reduced; and, applying his anti-rationalism to current belief, he fought zealously for the dogma that Mary, like Jesus, was immaculately conceived.456 But Occam, turning his predecessor’s tactic to a contrary purpose, denied that any matter of faith was demonstrable by reason at all. He granted that on rational grounds the existence of a God was probable, but denied that it was strictly demonstrable, and rejected the ontological argument of Anselm. As to matters of faith, he significantly observed that the will to believe the indemonstrable is meritorious.457