=The Causes of the Decay of the Civilization of the Middle Ages.= The social structure of the mediæval time weakened and broke apart, in the first place because of certain inherent defects in its organism; in the second place because of some remarkable discoveries, inventions, and historical changes. We may call these (1) _the internal causes_ and (2) _the external causes_ of the fall of the civilization of the Middle Ages. (a) _The Internal Causes_ were inherent weaknesses in mediæval intellectual life, and alone would have been sufficient to bring mediæval society to an end. (1) _The intellectual methods_ of the Middle Ages were self-destructive methods. We may take scholasticism as the best expression of the intellectual life of the Middle Ages, and scholasticism even in its ripest period used the _method of deductive logic_. Scholasticism did not employ induction from observation and experiment, but proceeded on the principle that the more universal logically a conception is, the more real it is. (See vol. i, p. 355.) On this principle scholasticism set as its only task to penetrate and clarify dogma. Its theism was a _logical_ theism. Even Thomas Aquinas, the great classic schoolman, used formal logic (dialectics) as the method of obtaining the truth. After him in the latter part of the Middle Ages, logic instead of being a method became an end. It was studied for its own sake. This naturally degenerated into word-splitting and quibbling, into the commenting upon the texts of this master and that, into arid verbal discussions. The religious orders frittered away their time on verbal questions of trifling importance. The lifetime of such intellectual employment is always a limited one. (2) _The standard of the truth_ of things in the Middle Ages became a double standard, and was therefore self-destructive. Ostensibly there was only one standard,――infallible dogma. Really there were two standards,――reason and dogma. The employment of logical methods implied the human reason as a valid standard. Logic is the method of human reasoning. To use logic to clarify dogma, to employ the philosophy of Aristotle to supplement the Bible, to defend faith by argument, amounted in effect to supporting revelation by reason. It was the same as defending the infallible and revealed by the fallible and secular. It was the erecting of a double standard. It called the infallible into question. It was the offering of excuses for what is supposedly beyond suspicion. The scholastic made faith the object of thought, and thereby encouraged the spirit of free inquiry.