Mercier Désiré-Joseph (1851–1926), Belgian Catholic philosopher, a formative figure in Neo- Thomism and founder of the Institut Supérieur de Philosophie (1889) at Louvain. Created at the request of Pope Leo XIII, Mercier’s institute treated Aquinas as a subject of historical research and as a philosopher relevant to modern thought. His approach to Neo-Thomism was distinctive for its direct response to the epistemological challenges posed by idealism, rationalism, and positivism. Mercier’s epistemology was termed a criteriology; it intended to defend the certitude of the intellect against skepticism by providing an account of the motives and rules that guide judgment. Truth is affirmed by intellectual judgment by conforming itself not to the thing-in-itself but to its abstract apprehension. Since the certitude of judgment is a state of the cognitive faculty in the human soul, Mercier considered criteriology as psychology; see Critériologie générale ou Théorie générale de la certitude (1906), Origins of Contemporary Psychology (trans. 1918), and Manual of Scholastic Philosophy (trans. 1917–18). See also AQUINAS, NEO-THOMISM. D.W.H.