b. 1662
The Port-Royal Logic (La Logique ou l'Art de penser, 1662) is a landmark treatise in early modern logic co-authored by Antoine Arnauld and Pierre Nicole at the Jansenist Abbey of Port-Royal. It synthesized Cartesian epistemology with Aristotelian logic, introducing influential analyses of ideas, judgments, and reasoning. The work is notable for its early treatment of probability and for distinguishing between the mental, spoken, and written dimensions of language.
Introduced one of the earliest formal treatments of probability and expected value in the context of reasoning
Distinguished comprehension (intension) from extension in the analysis of ideas, foundational for modern intensional logic
Synthesized Descartes's epistemology with traditional syllogistic logic
Analyzed future contingents and their implications for modal and conditional reasoning
Influenced subsequent logic texts for over two centuries, shaping both Continental and British logical traditions