Thomism’s influence began to wane in the 17th century when scholarly interest shifted from dogmatic theology, which concerns church doctrine, to moral theology, which concerns practical moral principles for everyday life. Nevertheless, dictionaries of Aquinas’s ideas and texts and numerous works of apologetics and exposition continued to be published, especially in France, indicating Aquinas’s considerable presence in French philosophical scholarship. The Thomist scholars John of Saint Thomas, Vincent de Contenson, and Charles-René Billuart produced multivolume works in the 17th and 18th centuries. Because Aquinas’s pedagogical method of posing and answering theological questions had fallen out of favour, John and subsequent thinkers reorganized Aquinas’s writings under thematic categories (e.g., logic, philosophy of nature, and metaphysics). They also juxtaposed Aquinas’s works with contemporary meditative texts in order to make his philosophy appear more relevant to current issues of belief and practice.

Until the mid-19th century, Scholasticism (the philosophical systems of medieval Christian thinkers) and Thomism were little known outside Roman Catholic seminaries. The dominant philosophers of the 17th and 18th centuries, including René Descartes and Immanuel Kant, rejected the medieval foundations of philosophy and theology. From the late 18th century the school of German idealism, represented by G.W.F. Hegel, Friedrich W.J. von Schelling, and Johann Fichte, eschewed Aquinas’s emphasis on natural creation and on the particularity and uniqueness of human nature.

By the middle of the 19th century, church authorities and some university faculties had become convinced that the Christian faith could be defended against modern idealist and subjectivist philosophies by deploying the realism of Aristotle and Aquinas. In opposition to Hegel’s view of reality as the self-realization of “Spirit,” they affirmed the stability of aspects of the external world. The renewal of Thomistic thought was advocated by three influential Jesuit writers in Italy and Germany: Luigi Taparelli d’Azeglio, Matteo Liberatore, and Joseph Kleutgen. Their own positions in epistemology, metaphysics, and social theory remained eclectic, but they did give impetus to the work of studying Aquinas and other Scholastics in the light of modern intellectual and social issues.

Decisive support for the movement came with Pope Leo XIII’s encyclical Aeterni Patris (1879; “Eternal Father”). It noted the importance of sound doctrine for meeting contemporary problems and called for a restoration of the Christian philosophy of the Church Fathers and Scholastics, augmented where necessary by the reliable advances of modern research. Leo asked especially for a recovery of the wisdom of Aquinas, whom he hailed as “the special bulwark and glory of the Catholic Faith.” This program required an accurate historical study of Aquinas himself and his major commentators, combined with a readiness to use the evidence and resources of modern learning and science. In 1880 Leo made Aquinas patron of all Roman Catholic schools. The Code of Canon Law of 1917, the official compilation of church law, required that Catholic teachers of philosophy and religion follow the method and principles of Aquinas. This established Thomism as the official philosophy of the Roman Catholic Church.

The Thomistic revival, known as neo-Thomism or the third Thomism (after the Thomism of Aquinas himself and the Thomism of his earlier interpreters), developed in a variety of directions in the first half of the 20th century. The historical studies of Étienne Gilson and Marie-Dominique Chenu on theology in the 12th and 13th centuries enhanced scholarly understanding of Aquinas and his writings. A.D. Sertillanges and Jacques Maritain employed Aquinas’s ideas to address modern art, science, and society. Thus, Maritain applied the Thomistic concepts of person and community to the problem of democracy. Several theologians—including Desiré-Joseph Mercirer, Joseph Maréchal, Pierre Rousselot, Erich Przywara, Ererich Coreth, J.B. Lotz, Karl Rahner, Gustav Siewerth, and Bernard Lonergan—explored potential affinities between Thomism and modern schools of philosophy such as idealism, phenomenology, and existentialism. Other theologians found that Thomism offered a philosophical approach that could serve as an alternative to other medieval or modern schools of thought or as an apologetic response to modern philosophical traditions. One such thinker, Réginald Garrigou-Lagrange, composed defenses of Aquinas’s philosophy, commentaries on the Summa theologiae, and writings on the Christian life.

During the first half of the 20th, century neo-Thomism provided the standard against which every Catholic intellectual movement was measured. Many of its advocates believed that no other way of thinking should be tolerated within the Roman Catholic Church. Unlike the thought of Aquinas, therefore, neo-Thomism in this period was generally rigid and intolerant, overly concerned with logic and metaphysics and disinterested in the religious depth of Aquinas’s writings. What many scholars and theologians referred to as Thomism or neo-Thomism, therefore, was in fact a generic and rather shallow variant of neo-Scholasticism, a contemporary movement also hearkening back to medieval thought but promoting several positions that were contrary to those of Thomas Aquinas.

Thomism following the Second Vatican Council

The Second Vatican Council (Vatican II), which promoted pastoral renewal and greater openness toward non-Western cultures, ended the dismissive attitude of some Roman Catholic thinkers toward non-Thomist theologies. The monopoly exercised by neo-Thomists in the church collapsed, and Aquinas’s influence was reduced. Although the ramifications of Vatican II at first seemed disastrous for Thomism, the council nevertheless provided theologians with ample opportunity to return to the basic principles of Aquinas’s theology and to apply them to matters not commonly treated by neo-Thomists. Thomistic concerns that found new expression after Vatican II included the mission of the Holy Spirit, the anticipation of the eschaton (end times), and Christ as the head of the human race. Drawing from themes in Aquinas’s theological framework, Roman Catholic thinkers argued that God’s grace could be found at work in the seven sacraments, the liturgy, church ministries, and social movements. Theologians after Vatican II applied Aquinas’s insights to medical ethics, Christian virtues, Christian spirituality, and human rights.

In the 1970s new scholarly resources and studies began to appear. In 1974, the seventh centenary of Aquinas’s death, Pope Paul VI issued a commemorative letter; in that same year a new interest in Aquinas manifested itself in congresses, multivolume collections, computer indices, and centres of Thomistic studies. Major works on Aquinas by Ghislain Lafont, Albert Patfoort, Otto Pesch, Ulrich Horst, S.T. Bonino, and Jean-Pierre Torrell were published in the 1980s and ’90s. These studies, the culmination of the vast research pursued during the 20th century into the historical and religious context of Thomistic thinking, testified to the influence that Aquinas’s thought continued to exert in the 20th and 21st centuries.