Aeterni Patris and the Making of a Modern School

For six centuries after his death, Thomas Aquinas was one respected scholastic voice among several, read alongside Bonaventure, Duns Scotus and Ockham rather than above them. Thomism as a distinct, self conscious school is largely a nineteenth century creation, and the document that made it one has a name and a date. In 1879 Pope Leo XIII issued the encyclical Aeterni Patris, calling on Catholic education to return to Aquinas as its philosophical foundation against what the encyclical treated as the errors of modern thought since Descartes. The result was the Leonine edition of Aquinas's complete works, a wave of seminary curricula built around his Summa Theologiae, and a twentieth century revival that produced philosophers of real standing in their own right rather than mere commentators.

What survived the revival is a recognizable set of commitments rather than a museum piece. Thomism holds that existence and essence are really distinct in every created thing and identical only in God, that the intellect can demonstrate God's existence from the created order without appeal to revelation, and that natural law provides a standard of right and wrong accessible to reason alone. Those commitments still organize Catholic moral theology and much of Catholic philosophy of religion today, which is why Thomism remains distinguishable from scholasticism in general: it is one particular current within a much wider medieval movement, promoted to official status by a decision the wider movement never received.