What is Thomism?

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.

All entries copyright © 2010 Glenn Smith. All rights reserved. Use of any material without permission will cause your concience to bother you for the rest of your life.

10 Responses to What is Thomism?

  1. Ryan says:

    What are your thoughts on this:

    Aquinas became a Dominican monk from the age of sixteen and is perhaps the most well known of all the mediaeval scholars, his saintly life occasioning him to be canonised eventually by the Roman Catholic church. In addition to his theological writings and his commentaries on Aristotle,

    Aquinas also wrote on natural science, where he declared that alchemy was a true art and where he also asserted that astrological theory had an important part to play in the study of natural science.

    Although he condemned most forms of divination (such as necromancy) as the work of demons, he grants that those divinatory arts which have a natural basis are permissible.


    Is this true?

    • humblesmith says:

      The first thing to note is that this author does not cite a reference; that alone should make one suspicious. Thomas wrote many dozens of volumes, and without a citation, it is difficult to trace these things down. Further, since many modern authors do not grasp the context of Thomas, often he is misunderstood.
      That said, let’s take these acusations. First, alchemy in the 1200’s was rudimentary chemistry, and even if Thomas approved it, it says nothing positive or negative about him. As to astrology, nearest I can tell Thomas never used the word or the modern concept. He did frequently speak of “heavenly bodies” using the term as if the reader knew what he meant; it is often unclear to me whether he meant planets and stars or bodies of heavenly creatures. But if we assume he was speaking of planets, keep in mind he was using Aristotelean cosmology, a system that was supported by the scentific community for 1800 years. Nearest I can tell, Thomas never supported astrology. In the Summa Theologica I-II.9.5 II-II.95, Thomas denies that heavenly bodies can move the human will, except in the sense of humans reacting to what we see. He repeats this denial in Compendium Theologiae Ch. 128. Without more specifics, the claim by the author on Thomas and astrology is baseless.
      As for divination, I will have to defer to later when I have more time to research. But I suspect that he might have been speaking of natural means that could be possible. Again, the lack of citations makes it difficult to confirm.

      But if the suggestion is that somehow Thomas is flawed due to these things, my response would be this: Like every man, Thomas is flawed. He did not have perfect theology, and followed official Roman Catholic theology in the places where protestants would disagree. Although he lived 300 years before the reformation, and it is not fair to measure him by that controversy, his writings on justification and salvation should necesarily be rejected, and soundly so. Nevertheless we can learn from his other writings, of which we would do well to study today, for he provides many useful answers in theology and philosophy.

  2. Ryan says:

    I found this blog provided an interesting overview of this -http://socrates58.blogspot.com.au/2006/05/did-st-thomas-aquinas-accept-astrology.html

  3. Ryan says:

    Please let me know what you think

  4. humblesmith says:

    This blogger quotes from Aquinas’ master work, Summa Theologica, II-II.95.1. The writer reads Thomas well.
    If you follow the link in the blog, it will take you to the Summa. Those new to Thomas sometimes do not read Thomas correctly; when he states “It seems that….,” Thomas is about to explain a view he disagrees with. Thomas will then say “But I say that….” where he explains his view. If you read questions 1 to 8 carefully, Thomas says that all forms of foretelling the future outside of natural means is a sin, and lists several kinds and forms of sinful divination.
    The only predicting of the future that Thomas allows is things like predicting the weather by viewing natural signs, predicting eclipses by observing the stars, and predicting people’s health by watching their habits. He clearly condemns all other forms of fortelling the future as sinful.
    The only minor point I’d note is that Thomas views some heavenly signs as indicators of natural causes. The example Thomas gives is that a rainbow is a sign of good weather, but not the cause of good weather.

    • Ryan says:

      thanks again

      • Felix says:

        Of course, St Thomas accepted astrology and it’s wicked to deny this plain truth. But, that being said, let’s note that he did so on the authority of the scientists of his time. And that he pointed out that astrologists can’t give infallible predictions (because ultimately people have free will).

  5. humblesmith says:

    In the Summa Theologica II-II.95, especially question 5, Aquinas condems astrology and did not accept it. He was quite plain here, or as plain as Thomas can get. He concludes, “In the second place, acts of the free-will, which is the faculty of will and reason, escape the causality of heavenly bodies.” and a bit later in the same response says “Accordingly if anyone take observation of the stars in order to foreknow casual or fortuitous future events, or to know with certitude future human actions, his conduct is based on a false and vain opinion; and so the operation of the demon introduces itself therein, wherefore it will be a superstitious and unlawful divination.”

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