Posterior Analytics, Commentaries on Aristotle’s

Abstract

Beginning with the translation of Aristotle’s Posterior Analytics into Latin in the course of the twelfth century, the Latin authors of the Middle Ages presented a theory of demonstration – an argument that produces scientific knowledge by presenting the cause of the truth of the conclusion – based on that work, and largely exposited in connection with commentaries on it. Different versions of the theory were developed with different metaphysical commitments. Robert Grosseteste wrote the first widely circulated commentary, developing an Augustinian version of the theory. Then two different versions were developed by the Aristotelians, Albert the Great and Thomas Aquinas. William of Ockham developed a fourth version within his nominalist metaphysics. In all these versions, demonstration of natural causal knowledge was accommodated as well as demonstrations in mathematics. It was supposed by all that demonstrative knowledge is produced by the operation of human faculties within the environment of the natural world, but Augustinian thinkers presupposed the illumination of natural essences by the divine light in some way, consistent with their supposition that natural things enjoyed their essences through participation in forms in the mind of God, so that their functioning could only be understood through those forms. Thomists assumed that the natural essences of particulars had a causal force of their own, considered as universals, that was reflected in demonstrations in natural science, since it was responsible for the causal propensities of particulars. Following an Averroist line, Albert the Great (and his follower, Giles of Rome) and Ockham assumed that the causal connections underlying demonstrative knowledge are entirely between natural particulars.