The Catholic intellectual world (and beyond) is no doubt still mourning last week’s passing of Ralph McInerny. McInerny’s death, aside from providing an opportunity to reflect on his own legacy, also invites us to reflect on the body of learning known as Thomism.

While it has become common over the last several decades for theological enquiry to generally ignore the contributions of Thomistic thought, the tide seems to be turning in favor of an acknowledgment of St. Thomas as the true “common doctor” of the Catholic theological tradition.

So why study St. Thomas? Why are so many turning again to the teachings of this thirteenth-century Dominican friar? I’d like to propose at least three reasons.

First, St. Thomas was the great herald of the harmony of faith and reason. In our age, faith is not merely relegated to the sidelines of intellectual discourse, but some have made a career out of proving its inherent irrationality. Aquinas maintained that reason and faith are not opposed, but are mutually informing and enriching. Faith does not require a suspension of reason, nor does rationality require an abandonment of faith.

This enables Thomas to affirm the existence of a “natural theology,” the “first steps” man can take toward God with his natural powers alone. Thus, even without the aid of divine revelation, the human person can arrive at fundamental propositions such as the existence of God and the truths of natural law.

Second, Thomas understands theology as a unified science. The contemporary student of theology is normally introduced to a compartmentalized approach to revelation: one that encourages a separation of dogma from Scripture, morality from dogma, and spirituality from the rule of faith. For Aquinas, all of theology is unified under a common object: God. Furthermore, Thomas assures us that the principles of this sacred science are more certain than any human science, since they derive their certitude from the light of divine truth, not from the insight of a particular theologian.

Lastly, Aquinas unfailingly maintained humanity’s need for grace. While he remained generally optimistic about man’s natural capacities, Thomas knew that man is destined for much more than a purely natural relationship with God as first cause. The human creature is destined for a relationship with God as adopted son or daughter through grace. Thus, Thomas was careful to maintain a clear distinction between the natural order and supernatural order, a distinction that never confused God’s agency with ours.

This distinction between the supernatural and natural orders has become incredibly blurred in contemporary theology. The consequences of this approach, which is certainly not novel, can be seen in the failed theological projects of Western theology.

Pelagius maintained that supernatural help is unnecessary to reach God, exalting nature and depreciating man’s need for grace. Luther denied the natural order to the benefit of the supernatural, but grace became completely alien to the human creature. These two extreme positions are found again and again throughout the course of Western theology, and both are popular in various incarnations even today. The Thomistic approach seeks a via media between these extremes, which preserves both man’s capacity for grace and his fundamental inability to produce it or its effects himself.

McInerny once remarked, “My ambitions have never gone beyond wanting to be a spear carrier in the grand Thomistic opera.” McInerny fulfilled his ambition well. Many students of theology would do well to follow McInerny’s lead and turn to Thomas, since many of the theologians they study today (Congar, de Lubac, Balthasar, Rahner, among others) built their theological projects on a critique of some form or another of Thomism.

While St. Thomas is generally gaining wider appreciation in intellectual circles, many disagreements remain. The tradition of revered commentators on Thomas’ works—like Cajetan, and the contributions of his more recent devotee, Garrigou–Lagrange—has been rejected wholesale with little explanation. Facile critiques of neo-Thomism which abounded in the conciliar era have been accepted indiscriminately.

These disagreements require serious attention, and they are far from being resolved. Nonetheless, perhaps it is time, following McInerny’s lead, to turn to Thomas again, just as his thought was employed by the Church time and time again for a refutation of error and a clear exposition of the whole of revealed truth. Our own time could no doubt benefit from such clarity.

Joseph Upton is a seminarian in the diocese of Providence, Rhode Island.