The first four volumes of Carl F. H. Henry’s magisterial God, Revelation and Authority carry the subtitle “God who speaks and shows.” God is the God who speaks, and Christians are people who love God’s words. We carry Bibles under our arms and installed on the smartphones in our pockets. We memorize God’s words, proclaim them in musical worship, and meditate on them as we seek to live as disciples of Jesus. As Peter says, “Lord, to whom shall we go? You have the words of eternal life” (John 6:68, NIV). But Christians also believe that God speaks in other ways beyond the Bible. We believe that God has “spoken” through the creation; that is, God has shown us truths through the world around us. But how has God done this?
Many Christians, from Paul to Augustine to Gottfried von Leibniz to William Lane Craig, have often investigated God’s revelation outside of the Bible, and in what follows, we introduce you to the fascinating work of Thomas Aquinas who, in his Summa Theologica, deduced five important ways in which we can come to see the truth that God exists apart from his revelation in the Bible and in Jesus Christ. This essay will focus on Thomas’s First Way, or the argument from motion, defending it as a fine piece of reasoning about the existence of God, and then explaining how using reason to investigate the existence and nature of God is an important gift for the church today.
The First Way
In Book I, Question 2, Article 3 of the Summa, Thomas gives us the first of the five ways, which he calls “the argument from motion.” Now when he says “motion,” he means something more like change; however, the idea of movement is helpful to keep in mind in what follows. He claims that we perceive things in our experience to be in motion; that is, we see things changing. An example of this would be some wood that has been set ablaze. The fire puts the wood “in motion,” so to speak, by changing the wood from something that was not ablaze to something that is ablaze. In discussing the wood and fire this way, Thomas is trading on the Aristotelian categories of potentiality and actuality. Wood is potentially hot, and fire is actually hot. So when set ablaze, the wood is moved from potentiality to actuality with respect to heat. We see this “motion” or change happen all the time in our everyday experience. The process of movement from potentiality to actuality is related to what Aristotle called efficient causation. “There is the proximate source of change or rest…the father is the cause of his child; and, in general, what produces is the cause of what is produced, what does the changing is the cause of what is changed.”[1]
An additional point that he makes about the wood is that it is not potentially hot and actually hot in the same respect. By this, he is not saying that part of a piece of wood may not be ablaze without the whole of the wood being ablaze. A partially ablaze piece of wood would be actually ablaze and potentially ablaze in different respects. Additionally, a piece of wood cannot be the source of its own change from potentially hot to actually hot. Again, this is obvious because a pile of wood does not spontaneously combust. It must be acted upon by some other thing in order to catch fire. So he says, “Whatever is in motion must be put in motion by another.”[2]
From there, he suggests that everything that we observe in motion has been “put in motion” by another thing, which has been put in motion by another thing, and so on. Yet if we see a linked chain of things putting other things in motion, it may be tempting to simply say that this process has been going on forever, but this is exactly the conclusion that Thomas wishes to forestall. No, we would not see change now if there had been an infinite chain of changing things. “Subsequent movers move only inasmuch as they are put in motion by the first mover.”[3] Since the fire that we see is a subsequent mover of a previous mover (Imagine the camper who has struck his steel and flint together), there must be a first mover.
But why? There must be a first mover because each subsequent mover must have had a previous mover. But there would be no subsequent movers without a first mover. This is what philosophers call the problem of infinite regress. Without a first mover, nothing is set in motion. The philosopher Peter Kreeft explains that subsequent movers without a first mover “would be like a train composed of an infinite number of boxcars all moving uphill without a locomotive, or like a stairway with an infinite number of steps each resting on the one below it but with no first step.”[4] Both of these ideas are absurd. If this concept is obscure, think about counting back to negative infinity starting at zero. You would never get to negative infinity, and not because you would run out of time. It is impossible to traverse an actually infinite set of “movers.” To avoid this absurdity, Thomas commends the only other possible explanation for motion, “Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands to be God.”[5] So we have, as the first cause of motion, a Prime or First Mover.
- In our experience, a thing in motion is put in motion by another thing, such as wood which is set on fire.
- Typically, that which puts something in motion has itself been put in motion by another thing.
- Either (A) a first mover exists, or (B) the chain of things put in motion by other things goes on to infinity.
- An infinite regress of things putting other things in motion is impossible (not-B).
- Therefore, (A) a first mover exists, which we call God.
When I was a youth pastor, I taught this apologetic argument to my students by selecting four rough-and-tumble junior high boys, placing them front-to-back in a line with their hands in front as if they were ready to protect the quarterback, and then pushing the boy in the back of the line so that a domino-like fall would take place. After a laugh, I told them that they never would have moved without one of them bringing about the motion, and they actually moved because I initiated the motion. So it is with God, the universe, and ourselves. I then reminded the students that in our skeptical world where Christians are ridiculed for their belief in God, we Christians have good reasons for believing that God exists, and we can share those reasons with our unbelieving friends in order to lovingly challenge their skepticism. And those reasons don’t always have to come from the Bible or our devotional experiences with God; in fact, when we see that the First Way points to the existence of God, we can conclude that we have experienced God through our observations of change in the world.
Defending Natural Theology
This way of looking at God is called natural theology, and Christian natural theology is the discipline of using reason and logic to investigate God’s general revelation. General revelation is God’s revelation in the natural world, logic, and the human conscience and is distinct from God’s special revelation in the Bible (which is the definitive source of doctrine and practice), Jesus, and the Holy Spirit. We see the Bible testify to general revelation in a few key places (Psa. 19:1-6; Matt. 5:45; Acts 14:15-17; 17:24-29), but the idea is probably best expounded in Romans 1:18-20:
The wrath of God is being revealed from heaven against all the godlessness and wickedness of people, who suppress the truth by their wickedness, since what may be known about God is plain to them, because God has made it plain to them. For since the creation of the world God’s invisible qualities—his eternal power and divine nature—have been clearly seen, being understood from what has been made, so that people are without excuse (NIV).
An explanation of general revelation and its relationship to natural theology is important because some Christians have rejected or criticized natural theology, inaccurately identifying it with natural reason, which has been placed in opposition to special revelation. Thomas himself makes a distinction between grace and nature (I.2.2), with nature as something needing to be perfected by grace.[6] As Protestants today who have a commitment to sola scriptura, oppositional thinking about reason and revelation or nature and grace could cause us to throw out natural theology as misleading or potentially idolatrous because it is in opposition to God’s revelation in the Bible. However, Thomas does not see things this way. He claims that God is the source of reason, and reason is “The light of Thy countenance, O Lord…signed upon us” (I.84.5).[7] He claims that the existence of God is known to us as a preamble to faith, but that knowledge of God’s existence needs perfecting by grace, which is exactly what we have in what he calls “articles of faith” or “sacred doctrine.” Reason on its own does not tell us that God is triune or incarnate in Jesus Christ, but it does tell us that God exists, which is no insignificant thing.
Correcting this misunderstanding about general revelation and natural theology is helpful, but there are other reasons that some reject natural theology. Some claim that natural theology is ineffective given the noetic effects of sin. Reflecting on the doctrine of total depravity, some theologians have rejected the idea that an unbeliever can come to true knowledge of God apart from regeneration. John Owen says, “It is in consequence of this depravity or darkness of the mind, that unregenerate men are not able of themselves, by their own reason and understanding, however improved, to discern spiritual things when outwardly revealed to them, without an effectual work of the Spirit creating or inducing a new saving light into them.”[8] About natural theology Karl Barth says, “One might call it an objective possibility, created by God, but not a subjective possibility, open to man. Between what is possible in principle and what is possible in fact inexorably lies the fall.”[9]
This objection fails to understand both the nature of revelation and the nature of humanity. Regarding revelation, even Owen claims that an unregenerate person has spiritual things revealed to them. This is correct because God is the revealer. Indeed, the fact that God speaks entails that he is able to make good on the communication of his revelation to humanity. In fact, the concept of sin requires the moral responsibility of the human. Revelation that is (at least partially) understood is a precondition for human moral culpability. Moreover, human beings are made in God’s image, and the image of God is not destroyed by the fall. Being made in God’s image means that in finite ways, humanity resembles something of Jesus himself, who is the Logos, the God who is the foundation of reason, wisdom, and revelation.[10]
Another objection to natural theology is that since the arguments of natural theology do not lead to an understanding of the triune God of the Bible, natural theology inevitably leads to idolatry. Some have called this the sin of ontotheology, where reasoning about the existence and nature of God causes one to attempt to control the object of inquiry to mold it into an idol. While natural theology does not fully expound the nature and character of God as revealed in the Bible, it does confirm some key aspects of God’s nature as seen in scripture. For example, natural theology shows that there exists a God who is creator, powerful, eternal, personal, and good. Natural theology doesn’t remake God as an idol; it corroborates some of the biblical picture of God. Moreover, we don’t worship the God of natural theology; instead, natural theology should compel us to worship the God of the Bible with joy for the manifold witness of his power and goodness revealed in the created world. Significantly, natural theology can be a powerful bridge to unbelievers to help them to see that God exists, making them doubt their skepticism and seek out the other ways that God has revealed himself.[11]
May Thomas Aquinas’s solid argument for the existence of the unmoved mover challenge you to worship God more wholeheartedly, do apologetics more confidently, and engage in evangelism more willingly as you reflect on the greatness of God as revealed in the natural world.
Endnotes
[1] Aristotle, Physics II.3, in The Philosophy of Aristotle: A Selection with an Introduction and Commentary, ed. Richard Bambrough, trans. J. L. Creed and A. E. Wardman (New York: Signet Classic, 2003), 227. This is distinct from material causation, such as when a ring is made of gold; formal causation, such as the mold into which the ring is poured; or final causation, or the purpose for which the ring exists, like the token of a marriage covenant.
[2] Saint Thomas Aquinas, A Summa of the Summa: The Essential Philosophical Passages of St. Thomas Aquinas’ Summa Theologica Edited and Explained for Beginners, ed. Peter Kreeft (San Francisco: Ignatius Press, 1990), 65.
[3] Ibid.
[4] Peter Kreeft, A Summa of the Summa, 66, note 21.
[5] Aquinas, A Summa of the Summa, 65.
[6] Aquinas, Summa of the Summa, 59.
[7] Ibid., 313. He is quoting Psalm 4:6. See also Francis Selman, Aquinas 101: A Basic Introduction to the Thought of Saint Thomas Aquinas (Notre Dame: Ave Maria Press, 2007), 20.
[8] John Owen, The Holy Spirit: His Gifts and Power (Grand Rapids, MI: Kregel Publications, 1954), 148.
[9] Karl Barth, “No!” in Natural Theology Comprising “Nature and Grace” by Professor Dr. Emil Brunner and the reply No! by Dr. Karl Barth, trans. Peter Fraenkel (London: Centenary, 1946), 106.
[10] For more on the so-called Reformed objection to natural theology, see Douglas Groothuis and Andrew I. Shepardson, The Knowledge of God in the World and the Word (Grand Rapids, MI: Zondervan Academic, 2022), 34-39.
[11] For more on the ontotheology objection, see Andrew I. Shepardson, Who’s Afraid of the Unmoved Mover?: Postmodernism and Natural Theology (Eugene, OR: Pickwick Publications, 2019), 100-115; and Groothuis and Shepardson, The Knowledge of God in the World and the Word, 45-48.
Credo Magazine
Advertisment
