Stephen Langton, later Archbishop of Canterbury and the famous signatory of Magna Carta, was a prominent intellectual, belonging to the first generation of scholars working at the faculty of theology of the nascent University of Paris. The I^ Quaestiones Theologiae constitute his chief speculative work. Book III, volume 3, offers a critical edition of 42 disputed questions about ethics. A critical apparatus and rich source notes accompany each text. The edition is preceded by an extensive analysis of Langton's selected ethical theories, concerning, among other issues, mendacity (lying, perjury, hypocrisy, fraud), moral dilemmas (double bind), obedience, and avoiding suffering. In addition, the introduction analyses Langton's discussion of some logical issues, such as I^propositio implicita and ampliatio .