Introduction

Robert Kilwardby was born in England, probably around 1215, and seems to have studied in Paris in the 1230s. He entered the Dominican order and was made Prior Provincial of the English Dominicans in 1261. In 1272 he became Archbishop of Canterbury, a post he held for about five years. In 1277 he forbade the teaching at Oxford of thirty propositions in grammar, logic, and natural philosophy, apparently taking his cue from the more famous condemnation by Stephen Tempier at the University of Paris. In 1278 Kilwardby was named Cardinal Bishop of Porto; he died the following year.

The work from which the following selections are translated is Kilwardby's De ortu scientiarum, a classification of the sciences that relies heavily on Aristotle. The subject of logic is reasoning and its end is the investigation of truth, according to Kilwardby, and he builds his analysis of the nature of logic around the various books of Aristotle's Organon. After explaining that logic in general is the science of discourse, Kilwardby proceeds to discuss logic more specifically as the science of reasoning systematically. This science of reasoning can be divided into demonstration, reasoning based on considerations specific to a particular science, and dialectic, reasoning that proceeds from common considerations and results only in opinion. Both demonstration and dialectic rely on syllogisms, the subject of Aristotle's Prior Analytics, but differ in the sorts of syllogisms they use.