What Are Some Other Arguments for God’s Existence?

From the early church onward, Christians have produced many rational and philosophical arguments for God’s existence as they reflected upon the world. This should not be surprising given the testimony of Romans 1:20, which reads, “His invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse.”

We will review some additional arguments that bear a strong witness to God. They will come primarily from Thomas Aquinas (c. 1225–1274), who was not only one of the most prolific Christian authors in history, but someone who gave an abundance of arguments for God. In the previous post we looked at the classical forms of the cosmological, teleological, and moral arguments; in this chapter, the goal is to present three additional arguments that may not be as familiar.

Arguments for God’s Existence Argument from Motion

While several have provided an argument from motion for a first unmoved mover, perhaps the best of these is found in Aquinas’s Summa Theologiae, popularly known as the first of his Five Ways and discussed in more length in his Summa contra Gentiles.[1] The argument is summarized as follows:

1. It is evident to our senses that in the world some things are in motion.

2. Everything put in motion is put in motion by a mover.

3. There cannot be an infinite regress of movers going backward. If there is no first mover, there can be no subsequent motion.

4. Therefore, there is a first unmoved mover; this is God.

Let us take a closer look at each part of the argument.

1. It is evident to our senses that in the world some things are in motion.

Aquinas strategically started from motion observed in the world all around us. Local physical motion is the most obvious, as when you move from place to place, but motion can also apply to quantities or qualities, as when a plant grows larger or an apple becomes more red.

2. Everything put in motion is put in motion by a mover. This should not be surprising, for every change needs a changer, and every effect needs a cause. When some potential to move is put into motion, then that potential has been actualized. Prior to this, it only had the potential (what can be) and needed another mover to bring about the change in motion. Something cannot be potentially moving and actually moving in the same respect. It is either one or the other. The consequences are that a potential cannot actualize itself. There has to be something outside that potential, a mover that is already actualized—that is, already existing. Even with created composite self-movers such as animals and humans, one part moves another, for no part can move itself. For example, the will moves the nerves, the nerves fire the muscles, which moves the leg, which moves the body, etc. Even the cognitive and volitional faculties of thinking or willing have not always existed, for something prior to them needed to bring those faculties from mere potentiality to actuality.

In addition, the potential of something limits what kind of change is possible. For example, a block of stone has the potential to be a statue, but not the potential to be an actual person. A gallon-sized jug has the potential to hold one gallon of liquid, and once that jug is full, then that potential has been actualized and no more potential remains for additional liquid. Things in the natural world vary in their mixture of potentiality and actuality. Some things have more potential for motion or change than other things.

3. There cannot be an infinite regress of movers going backward. If there is no first mover, there can be no subsequent motion. If every potential to move or change needed something actual, and if what was actual at one time was in potential, then it also needed something prior that was actual, and so on. Aquinas reasons that this cannot go on infinitely backward (infinite regress). Each potential that has been actualized required something prior to bring about the change. If something went infinitely backward, then it would not have a beginning, as you cannot reach the edge of an infinite. Aquinas emphasized that there has to be a first mover to get the motion started. If there is no first actualizer, there can be no subsequent motion.

Some have been confused on how this might relate to Newton’s first law, which says, “Every body perseveres in its state of being at rest or of moving uniformly straight forward, except insofar as it is compelled to change its state by forces impressed.”[2] That is, a body that is at rest or in motion tends to stay in that state unless acted on by another. However, this does not negatively affect the basic principle of Aquinas’s first way. For whatever is moved is moved by another, and whatever is changed needs a changer, just as every effect needs a cause. Newton’s law in fact supports that there needs to be something to cause the body to change from a state of rest to a state of motion or vice versa. Aquinas’s argument does not conflict with this, as his argument was interested in what brought about the first motion. The alternative is that there is eternal motion, but that cannot be, as there cannot be an infinite regress of prior changes. Nor can there be some reciprocal or cyclical eternal causality, such as one thing, B1, causes another, B2, which in turn causes a change back on B1 infinitely backward.

There still needs to be an accounting of the first movement, since motion, as a series of changes, cannot go back infinitely. If it did, then the infinite number of changes could not be crossed to arrive at the present and current change. Hence, an infinite regress is impossible.

4. Therefore, there is a first unmoved mover; this is God. Tracing the motion to its source, Aquinas arrived at a first unmoved mover that is needed to account for all subsequent motion. This is God. God has no beginning, and nothing else actualized Him. God has always existed (Psalm 90:2). Neither can God change, for He has no potential to change (Malachi 3:6). Therefore, God is pure actuality and the first unmoved mover. God is the great “I am” (Exodus 3:14), who gave motion to everything else.

Argument from Contingency

Another argument provided by Aquinas in Summa Theologiae Ia.2.3 is known as his third way. It was an argument from contingency to necessity.

1. Contingent (dependent) beings exist (e.g., I am a contingent being).

2. A contingent being needs a cause for its existence.

3. An infinite regress (going backward infinitely) of contingent causes is impossible.

4. Neither can one contingent being cause another contingent being.

5. Therefore, there must be a Necessary Being that is the cause of every contingent being. This is God.

This is a shortened and slightly reformulated form of the argument. To understand the connection further, let us go through each part of the argument.

1. Contingent beings exist (e.g., I am a contingent being). In nature we find beings that begin and cease to exist; these are known as possible or contingent beings. These are not self-existent beings. In other words, they do not have existence by nature, for if they did, then they would have always existed. Human beings are an example of a contingent being. We do not have existence by nature and have not always existed. Our existence is dependent upon another, and this cannot be our parents. Our parents are only the instrumental cause (i.e., the instrument through which) of our becoming, but not the cause sustaining us in existence. Why? Every effect needs a cause, and if you remove the cause, then the effect does not follow.

If our parents were the primary single cause, then when they died, we (the effect) would cease also. But when parents die, their children remain. The same is true of the blacksmith with his hammer, for he is only the cause of the becoming of horseshoes. When the blacksmith passes away, the horseshoes remain. This is because there is another cause sustaining them in their being.

2. A contingent being needs a cause for its existence. A contingent

(dependent) being is a being that came to be, and can cease to be. Whatever begins to exist does so only through what already exists. Consequently, a contingent being needs a cause for its existence. It cannot cause itself, for then it would be prior to itself, which is absurd. Something else had to bring it into existence.

3. An infinite regress of contingent causes is impossible. There cannot be an infinite regress, because an infinite cannot be crossed—that is, you cannot get to the other side of it. Moreover, adding more contingent beings to the series does not get rid of the contingency, because the whole thing is still contingent, and needs a cause for its existence.

4. Neither can one contingent being cause another contingent being. Consequently, a contingent being cannot be the primary cause of another contingent being to exist, for a being cannot give what it does not have essentially. If a being is contingent, then it does not have its own existence to give. Imagine several people lined up to pay for admission tickets at the entrance of a movie theatre. When the cashier asks the first person for money, that person—and all the others—points to the person behind him and says, “My friend will pay.” Then the last person in line becomes exasperated and says, “I don’t have any money.” None of the people earlier in line have money to give, just as none of the prior contingent beings have existence of their own to give. Here’s another way to think about this: I only contingent beings existed, then there would be nothing to explain or be the ground of their existence. Simply adding more contingent beings never provides the basis for existence.

5. Therefore, there must be a Necessary Being that is the cause of every contingent being. This is God. The fact that some contingent beings exist means that something must have always existed, for if there ever was a time when there was absolutely nothing, then there would have always bee nothing. Consequently, there must be a Necessary Being whose essence it is to exist and is the primary cause of existence for all contingent beings. This is God. The question for the atheist is this: Why is there something in existence rather than nothing at all? The reason is that there is a God who brought all things into being. Stated in terms of dependency for the

universe, the sequence would look something like this:[3]

1. Every part of the universe is dependent.

2. If every part is dependent, then the whole universe must also be

dependent.

3. Therefore, the whole universe is dependent for existence right now on some independent being—namely, God.

Adding more dependent (or contingent) beings can never remove the dependency. You have to continue back to something that is necessary, something whose nature it is to exist. This is God. In theology proper (the study of God’s attributes), the term aseity (Latin, “of oneself”) is used to denote this most amazing truth that God is self-existent (Genesis 1:1; Exodus 3:14; Psalm 90:2; John 1:1; Romans 11:36; Colossians 1:17).

Argument from Perfection

In his fourth way, Aquinas provided an argument from the gradations of things to a most perfect being (Summa Theologiae Ia.2.3), as did an earlier theologian by the name of Anselm of Canterbury (1033–1109) in his Monologium.[4]Taking the best of these both produces the following argument for God’s perfection:

1. We observe that some beings are more nearly perfect than others.

2. The cause of this perfection is either one or many.

3. If there were many, there would be no way to compare their perfection, but some things are more perfect than others.

4. Moreover, things cannot be more or less perfect unless there is one wholly perfect source and standard for comparison.

5. Therefore, there must be a most perfect being who is the source of all perfections. This is God.

Several points can be made about each premise.

1. We observe that some beings are more nearly perfect than others. As we live, we make comparisons every day with regard to the objects around us to determine what to buy or sell, whom to marry, and so on. And when we do, we find that some things are more or less perfect, noble, true, or good than others.

2. The cause of this perfection is either one or many. When thinking

about what causes these perfections, it seems natural to inquire whether one or more things cause them. The other option is to say there were no causes, which is impossible given that an effect cannot arise without a cause (the law of causality). All perfections in contingent beings need a cause, a source from which they came.

3. If there were many, there would be no way to compare their

perfection, but some things are more perfect than others. When we are unable to easily compare things in a practical way, we say, “It is like comparing apples and oranges.” Yet Aquinas was not referring to practical or utilitarian comparisons. As we compare things, especially across categories, we may begin to realize that we are comparing them at a more fundamental level. Aquinas was referring to a comparison of their quality of being because trueness, nobility, goodness, beauty, and perfection transcend physical and material categories.

For example, a man approaches these qualities of being more than a stone, and a being that has intelligence is better than a being that does not. So regardless of type, the thing that approaches perfection will exhibit more of these transcendent qualities. Another way to think about this is to imagine the result if perfections were removed. If you remove all the perfections from something, what are you left with? You would be left with nothing (nonbeing). If you have a totally moth-eaten shirt, you have no shirt at all. However, if you remove all the imperfections of something, what are you left with? You are left with something perfect (being). Therefore, when a thing is more perfect, it approaches the perfection of the pureness of being itself (pure actuality).

4. Moreover, things cannot be more or less perfect unless there is one wholly perfect source and standard for comparison. Observing that some things are better than others requires an objective standard by which to make the comparison—just as that which is hotter than another more nearly approaches that which is hottest. In terms of causation, an effect derives its perfection from its cause, for an effect cannot be greater than its cause. A cause cannot give what it does not have, but what it does have can be given to the effect. Hence, if some effects are more perfect than others, then they must be caused by a source of perfection.

5. Therefore, there must be a most perfect being who is the source of all perfections. This is God. As Aquinas eloquently stated in his fourth way, there needs to be a perfect being who is the source of all perfections (Matthew 5:48):

So that there is something which is truest, something best, something noblest and, consequently, something which is uttermost being; for those things that are greatest in truth are greatest in being…Therefore there must also be something which is to all beings the cause of their being, goodness, and every other

perfection; and this we call God.[5]

The Value of Knowing the Arguments for God’s Existence

There are many arguments for God available in the sources written across the ages of church history. This brief treatment is only a tiny fraction of what has been written on the subject. It is strongly encourage you to explore the other arguments more fully, as they can be edifying and can contribute to strengthening your faith. They can also be strategically used when you share your faith, as you are likely to encounter questions or alternative viewpoints regarding God’s existence. By becoming familiar with the various rational arguments, you can use them to remove objections others

may have toward the gospel. This does not necessarily mean quoting the arguments mechanically in their raw form. Instead, it means knowing the essence and truth of the arguments, then utilizing them strategically in conversational language.

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[1] Thomas Aquinas, The Summa Theologica of St. Thomas Aquinas, trans. Fathers of the English Dominican Province (Notre Dame, IN: Christian Classics, 1981), Ia.2.3. Thomas Aquinas, Summa contra Gentiles, trans. Fathers of the English Dominican Province (London, UK: Burns Oates & Washbourne, 1924), I.13.

[2] Isaac Newton, The Principia: Mathematical Principles of Natural Philosophy: The Authoritative Translation, trans. I. Bernard Cohen and Anne Whitman, assisted by Julia Budenz (Oakland, CA: University of California Press, 1999), Kindle loc. 76.

[3] Norman L. Geisler, Systematic Theology, vol. 1 (Minneapolis, MN: Bethany House, 2002), 30.

[4] Anselm, Basic Writings, ed. and trans. Thomas Williams (Indianapolis, IN: Hackett Publishing, 2007).

[5] Aquinas, Summa Theologica, Ia.2.3