Chaïm Perelman (1912–1984), a Polish-born philosopher of law, studied, taught, and lived most of his life in Brussels. He became the youngest full professor in the history of the Université Libre de Bruxelles, where he remained for the rest of his career. He was among the most important argumentation theorists of the twentieth century. The New Rhetoric: A Treatise on Argumentation, written with Lucie Olbrechts-Tyteca in 1958, and translated into English by John Wilkinson and Purcell Weaver in 1969, is his chief work. He is also the author of The Realm of Rhetoric (University of Notre Dame Press, 1982).
(L. is for Lucie) L.Olbrechts-Tyteca (1899–1987) was a Belgian academic and longtime co-worker of Chaïm Perelman. She volunteered in 1948 to support Perelman's work and developed several aspects of the New Rhetoric independently in later years.