John of St. Thomas (1589–1644)

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John of St. Thomas, the Spanish theologian and philosopher, was born John Poinsot, the son of an Austrian, at Lisbon, Portugal, and died at Fraga, Spain. When he entered the Dominican order he took his name from St. Thomas Aquinas. John studied philosophy at Coimbra, Portugal, and theology at Louvain, taught philosophy and theology in Dominican houses of study, at Alcalá de Henares (16131630), and from 1630 to 1643 was a professor at the University of Alcalá. Apart from certain Latin and vernacular works of devotion, his writings consist of two series of textbooks, one in philosophy, the Cursus Philosophicus (which comprises "Ars Logica," covering logic, and "Philosophia Naturalis," on natural philosophy), the other in theology, the Cursus Theologicus (a systematic commentary on Thomas's Summa of Theology ).

The "Ars Logica" is fundamentally Aristotelian logic, but John developed the content of the course in two directions: toward a formal theory of correct reasoning and toward a material logic that attends to the meaning of the actual terms of a proposition and thus anticipates some of the problems of epistemology and semantics. John's terminology differs from that of modern logic (propositio copulativa is the modern conjunctive proposition; propositio disiunctiva the alternative proposition; bona consequentia means implication ). However, it has been claimed, by J. J. Doyle, that the "Ars Logica" and Alfred North Whitehead and Bertrand Russell's Principia Mathematica are fundamentally similar as formal systems. Concerning material implication, John taught that one may infer from the particular proposition ("Some man is rational") to the universal proposition ("Every man is rational") in cases where the matter is necessary. To some extent he anticipated problems in the philosophy of science and the metasciences and also the theory of induction.

His philosophy of nature is a systematic exposition of a type of Thomism much influenced by the commentaries of Cajetan. Nature is the world of bodies, of being that is subject to change (ens mobile ), explained in terms of the four Aristotelian causes, substance and accidents, act and potency, matter and form.

John treated certain questions in a novel wayfor example, immanent action, the sort of activity that begins and ends within one agent and is typical of psychic functions (see Cursus Philosophicus, "Philosophia Naturalis," I, q. 14, a. 3). John had no separate treatise on metaphysics, but his views on the ultimate character of reality were frequently presented in his explanation of parallel problems (substance, causality, potency) in the "Philosophia Naturalis." The "Theological Course" also contains explanations of problems in speculative philosophy. Cognition, on the sensory and intellectual levels, is explained in terms of a metaphysics of causality (I, q. 1, disp. II, a. 12, n. 4). John was one source of the theory of the distinction between three degrees of knowledgephysical, mathematical, and metaphysicalpopularized in the twentieth century by Jacques Maritain.

In his discussion of the gifts of the Holy Ghost (Cursus Theologicus, IV, disp. XVII), John had much to say on the relation of knowledge to wisdom. He viewed ethics and political philosophy as speculative sciences and did not write much on practical philosophy. On moral questions he adopted the position called "probabilism"; that is, in moral situations where a person is really in doubt about what he should do, he may solve his doubt by adopting any judgment that has been made by a prudent moralist concerning the proposed action (Cursus Theologicus, IV, disp. XII, a. 3, n. 4).

John's writings are useful for their historical information on later scholasticism. He influenced many recent Thomists, notably Maritain, J. M. Ramírez, Joseph Gredt, and Yves Simon.

See also Aristotelianism; Cajetan, Cardinal; Induction; Logic, History of; Maritain, Jacques; Philosophy of Science, History of; Russell, Bertrand Arthur William; Thomas Aquinas, St.; Whitehead, Alfred North.


works by john of st. thomas

Cursus Philosophicus, 3 vols. Edited by Beatus Reiser. Turin, 19301937; 2nd ed., 1948.

Cursus Theologicus. Opere et studio Monachorum Solesmensium. Paris, Rome, and Tournai, Belgium, 1933.

The Material Logic of John of St. Thomas: Basic Treatises. Translated by Yves Simon, J. J. Glanville, and G. D. Hollenhorst. Chicago: University of Chicago Press, 1955.

Outlines of Formal Logic. Translated by F. C. Wade. Milwaukee: Marquette University Press, 1955.

works on john of st. thomas

Bondi, Eugene. "Predication: A Study Based in the 'Ars Logica' of John of St Thomas." Thomist 30 (1966): 260294.

Doyle, J. J. "John of St. Thomas and Mathematical Logic." New Scholasticism 17 (1) (1953): 338.

Furton, Edward J. A Medieval Semiotic: Reference and Representation in John of St. Thomas' Theory of Signs. New York: Peter Lang, 1995.

Gracia, Jorge J. E., and Kronen, John. "John of Saint Thomas (B. 1589; D. 1644)." In Individuation in Scholasticism, ed. Jorge Gracia. Albany: State University of New York Press, 1994.

Maritain, Jacques. Philosophy of Nature. New York: Philosophical Library, 1951. See for a reworking of details of John's theory.

Wolicka, Elzbieta. "The Notion of Truth in the Epistemology of John of St Thomas." New Scholasticism 53 (1979): 96106.

Vernon J. Bourke (1967)

Bibliography updated by Tamra Frei (2005)