Thomism is the teachings that follow the theology and philosophy of Thomas Aquinas (d.1274). Aquinas left a massive amount of writings, dealing with much of the same issues that people wrestle with in modern times. His most well-known work is the Summa Theologica, a huge work that deals not only with theology, but also lays a foundation for philosophy, psychology, and government. He deals with each topic by answering almost every conceivable question, dividing each problem into many sub parts, each of which proposes all the objections imaginable, then answering each objection. Therefore Thomas Aquinas’ work is both a statement of theology and a defense against critics.
Aquinas provides a well-reasoned foundation that answers many issues in Christian theology and philosophy. Distinctives of Thomistic theology and philosophy include the following:
- The human mind is capable of reasoning through problems based on observing effects in the world. Thus man can reason to the existence of God by observing effects in the universe. Divine truths that are beyond what we observe must be revealed by God
- When a man observes an effect, he can know that it has a cause. Learning about that cause is a natural desire of the human intellect.
- Therefore humans can observe nature and learn some things about God.
- The essence of a thing (e.g., what it is; the attributes) is distinct from the existence of the thing (e.g., that it is). Thus we can reason about existence separately from essence. Logically, existence precedes essence. Thus we must answer questions about existence before we can answer questions about essence.
- God is a necessary being, is simple (e.g., not compound). Just as a stone can be 100% gray and 100% hard, every attribute God has, He is that completely and necessarily.
- God is eternal, which is not “in time” but rather not bound by time.
- We know about God through analogy. Thus we know God is good and powerful, but we know “good” or “power” in a way that is analogous to how God is good or powerful, not in exactly the same univocal sense. This is true because man is finite, and God is infinite. Thus man can know God, but in an analogous sense.
- Modern problems in epistemology (how we know) are ultimately solved through metaphysics (how we exist) and by analogy of existence. Thomism denies that the knowledge in our mind is a representation of reality, but is instead another instance of reality.
- God causes things consistent with its essence, thus when God causes movement in the human will, He does so through human free will, and not contrary to human free will.
Authors who are influenced by Thomism include Norman Geisler, Thomas Howe, Joseph Owen, Jacques Maratain, George Klubertanz, Etienne Gilson, R. P. Phillips, and many others. Sources of how Thomism can be applied to evangelical theology and philosophy are:
- Norman Geisler, who published a four-volume Systematic Theology, and a book called Thomas Aquinas: An Evangelical Appraisal.
- Etienne Gilson, Being and Some Philosophers.
- Henry Babcock Veatch, Two Logics: The Conflict Between Classical and Neo-Analytic Philosophy.
For the beginner interested in Aquinas and for those who have little exposure to classical philosophy, I’d suggest starting with Geisler’s book Thomas Aquinas. For those who want to read Thomas, I suggest starting with Aquinas’ work titled Summa Contra Gentiles which is a bit more digestible, then try On Truth (De Veritate), a three volume set that is a little shorter. For those who have studied under modern analytic philosophers, the Veatch book Two Logics will show you the profound difference between classical philosophy and what you’ve learned.
Most of Thomas Aquinas’ writings can be found online in English by doing an internet search (try here). However, works such as Summa Theologica assume that the reader has already been well-versed in metaphysics.