Logic: or, The Art of Thinking

Logic; or, The Art of Thinking (La Logique, ou L'art de penser) is a significant work published in 1662 by Antoine Arnauld and Pierre Nicole. This treatise, often referred to as the Port-Royal Logic, was highly influential and widely reprinted in multiple languages.12

The book outlines a simplified approach to logic, following a structure of concept, judgment, argument, and method. A key contribution of the Port-Royal Logic was its distinction between the comprehension (essential attributes) and extension (objects to which a concept applies) of a term, a concept that influenced later thinkers like John Stuart Mill. It also discussed definitions, distinguishing between nominal and real definitions, a concept inspired by Blaise Pascal. While not using symbolism itself, the work laid philosophical groundwork for the later development of logical symbolism.1