Aristotle

Aristotle's theology is the last step of a physical argument, not the first step of a devotional one. Everything that moves, he holds, is moved by something; an infinite regress of movers explains nothing; so there must be a first mover that is not itself moved. Book twelve of the Metaphysics works out what such a thing would have to be. It cannot be made of matter, because matter carries potential and a first mover must be wholly actual. It cannot change, because change is the thing it exists to explain. It cannot act on the cosmos by pushing, because pushing would be a motion in it, so it moves the outermost sphere as an object of desire moves the one who desires, by being loved rather than by doing anything. And since the best activity available is thinking, and it can have nothing better than itself to think about, it is thought thinking itself.

What follows from that is as important as the argument. This god does not make the world, which for Aristotle has always existed and always will. It issues no law, hears no prayer, and knows no particulars, because knowing changing things would change it. It is not one of the gods of the city, and Aristotle nowhere suggests that anyone should worship it. Readers who wanted a creator, a lawgiver and a listener had to argue their way from this figure to that one, and the difficulty of doing so is most of medieval philosophical theology.

Aristotle reached the medieval world by translation rather than by continuity. Syriac Christian scholars carried the logical works into Arabic during the Abbasid translation movement, and Muslim philosophers took up the whole corpus: al-Farabi, then Ibn Sina, then Ibn Rushd, whose commentaries were so thorough that Latin readers called him simply the Commentator. Maimonides worked out of the same Arabic tradition to argue in the Guide of the Perplexed that scripture must be read figuratively wherever it contradicts a demonstrated conclusion, while insisting that the eternity of the world had not in fact been demonstrated. Latin Europe received the natural and metaphysical works late, and reacted first by banning them from the Paris arts faculty.

Three points would not reconcile. If the world is eternal it was not created. If the first mover knows only itself, providence has nothing to work with. And if the intellect that does the thinking is one and shared, no individual soul survives death. Each tradition answered differently and the answers hardened into positions: the Paris condemnations of 1277 list propositions of exactly this kind, and Thomas Aquinas built his synthesis partly by conceding that creation in time is known from revelation and not from reason. The atlas holds Aristotle among religious figures for that reason. He founded nothing and taught no religion, and three of them spent centuries arguing with him.