St. Thomas Aquinas and his followers are not normally associated with the theology of doctrinal development. Nevertheless, in his presentation of the faith-reason relationship and his treatment of the theological virtue of faith, Aquinas does forward an explicit and nuanced theology of doctrinal development. In the context of the relationship between faith and reason, Aquinas connects the natural knowability of God with truths formally revealed in faith, treating the latter as developments of the former, and thus establishing an organic continuity between truths known by reason and the articles of faith. In relation to the virtue of faith, St. Thomas presents a very robust understanding of the connection between the articles of faith and God as the object of faith’s assent.
A helpful and insightful treatment of doctrinal development according to Aquinas can be found in the book What is Dogma? by noted Swiss thomist, Charles Cardinal Journet. Journet’s What is Dogma? has recently been reprinted; it’s worth the read, especially for those interested in Aquinas’ theory of doctrinal development.