On Thomas Aquinas’ First Two Ways to Prove God: Motion, Cause, and Reflections on Time

Of all the arguments for God’s existence, perhaps the most well-known is Aquinas’ Five Ways. His ways are listed as follows:

• God’s existence can be proved by motion
• God’s existence can be proved by cause
• God’s existence can be proved from possibility to necessity
• God’s existence can be proved from gradation
• God’s existence can be proved by governance

This entry will reflect solely on the first two, the arguments from motion and cause.

Aquinas’ First Way: Argument From Motion

“The first…manifest way [to prove God] is the argument from motion. It is certain, and evident to our senses, that in the world some things are in motion. Now whatever is in motion is put in motion by another, for nothing can be in motion except it is in potentiality to that toward which is in motion; whereas a thing moves inasmuch as it is in act. For motion is nothing else than the reduction of something from potentiality to actuality. But nothing can be reduced from potentiality to actuality, except by something in a state of actuality. Thus that which is actually hot, as fire, makes wood, which is potentially hot, to be actually hot, and thereby moves and changes it. Now it is not possible that the same thing should be at once in actuality and potentiality in the same respect, but only in different respects. For what is actually hot cannot simultaneously be potentially hot; but it is simultaneously potentially cold. It is therefore impossible that in the same respect and in the same way a thing should be both mover and moved, i.e., that it should move itself. Therefore, whatever is in motion must be put in motion by another. If that by which it is put in motion be itself put in motion, then this also must need to be put in motion by another again. But this cannot go to infinity, because then there would be no first mover; as the staff moves only because it is put in motion by the hand. Therefore it is necessary to arrive at a first mover, put in motion by no other; and this everyone understands as God.”

–Thomas Aquinas, Summa Theologica, 1.2.3.

It befits us to regard the first way as not just reasoning from the motion of physical bodies, but the motion from one state of being to another. Let us say p has the potential of becoming q. Now, this could not occur unless this transition is prompted by another agent, say r. We can say this motion is prompted by a thing which in turn causes the transition, and this cause of the transition is one the result will mimic. If q is the outcome, then the attributes of q in its motion from p will mimic or reflect the properties of r. In the example of heat, wood, and fire, wood only has the potentiality of being affected by heat, but if caught alight by means of spark or heat, it resembles and takes on some of the attributes of the heat and fire which existed prior. Even in terms of physical motion, this is played out when a body interacts with another body, transferring a like energy to the other which then produces motion in another, even to the point of stillness or inertia in the cause.

It seems a jump to then reason, ‘this process cannot go on forever, because there would be no first mover,’ which seemingly presupposes the First Mover’s existence and thus disassembles any sound proof since; the conclusion is presupposed in its proof. If left to this statement alone, we would be justified in the conclusion of its falsehood. There is the prompt however to ask, “Why can’t it go on to infinity?” We recall the movement argument talks not of the movement of bodies interacting solely, but a potential quality becoming actual within a thing. This cannot go on forever because there would be no first mover to bring actually in anything, for only potentiality would exist, and potentiality alone does not exist, or cannot exist, as it is bound as a product of actuality.

Thus, for the universe to form, an ultimate actual thing must exist which causes the movement from potentiality to actuality in everything else. Furthermore, we might reason an actual thing, must bring about an actual thing for potentiality to exist (as opposed to an actual thing bringing about a potential thing), for there must be some Actuality free from potentiality since what is potential requires first actuality to come into being, but if Actuality created mere potentiality then this would not allow for motion. Thus, it is reasonable an Actuality created actualities, that by these interactions of what is actual, potentiality would come into being. This Actuality, the Prime Mover of all movement, is what everyone calls God.

A visual aid might help in this understanding and will serve in clarifying not only the First Way but the Second Way, which is related to the First.

The Prime Mover must be a thing Actual so the universe may exist since potentiality alone is nothing if there is no preexisting actuality. Also, it follows, in the beginning, actual things must have been brought into being, not merely potentialities for the same reason. Mere potentiality wouldn’t bring about anything. Also, as seen, it requires multiple actualities for potentiality to exist through their interactions.

Therefore, for the sake of illustration, this chart would be impossible:

If it were the case, the Prime Mover created potentiality, it would go no further. It would remain in a state of nothingness, so while the first illustration continues ad infinitum, the second one would not, and wouldn’t result in anything.

The resulting eternal nothingness of created potentialities.

For the same reason, a potential Prime Mover is impossible:

An impossible flowchart, since everything after the Prime Potentiality would be negated.

Thus, we find the first illustration is the only means by which we can account for the universe’s existence, that there must be a Prime Mover who at the onset of the universe, set actualities into their place, that by their interaction, potentialities may become extant and bring about other actual things. This is why we can’t extend this back into infinity, and a Prime Mover is necessary.

Now we continue on to Aquinas’ Second Way.

Aquinas’ Second Way: Argument From Cause

“The second way is from the nature of efficient cause. In a world of sense we find there is an order of efficient causes. There is no case known (neither is it, indeed, possible) in which a thing is found to be the efficient cause of itself; for so it would be prior to itself, which is impossible. Now in efficient causes it is not possible to go on to infinity, because in all efficient causes following in order, the first is the cause of intermediate cause, and the intermediate is the cause of the ultimate cause, whether the intermediate cause be several, or be only one. Now to take away the cause is to take away the effect. Therefore, if there be no first cause among efficient causes, there will be no ultimate, nor any intermediate cause. But if in efficient causes it is possible to go on to infinity, there will be no first efficient cause, neither will there be an ultimate effect, nor any intermediate efficient causes; all of which is plainly false. Therefore it is necessary to admit a first efficient cause, to which everyone gives the name God.”

Thomas Aquinas, Summa Theologica, 1.2.3.

The second way, Aquinas’ argument from causality, declares it empirically true and observable there exists a temporal element between cause and effect. It is clear a cause must come before an effect and though it may seem a cause and effect can exist simultaneously, it is diverged from by the temporal element. A cause can be an effect itself, but only when due to a prior cause, and this effect shifts from effect to cause when it produces an effect in something else. A process we see repeated ad infinitum. In this process, there are former efficient causes, the intermediate causes, and the ultimate cause, the latter being the last of the order. A notable thing about cause is it’s a necessary condition of any effect (which, as stated, could become the cause of another thing). It is impossible an effect would exist without cause. We see this as an obvious natural law.

If the universe has a cause for its being, then the universe as a whole is representative of an effect, and if the universe is an effect, or what might be called “caused,” it cannot be uncaused and a first cause must exist. It is impossible a “self-caused cause” could exist because it is self-contradictory and akin to saying the cause existed prior to itself. A self-caused effect cannot exist for the same reason, since it follows effect does not lead to cause, but cause leads to effect. It is quite easy to stretch the imagination to its limits and suppose an infinite chain of subsequent causality, but it is much more difficult to do so through infinite regress because of these natural considerations. Regardless, in the end, we must admit the existence of a First Cause, lest those who deny one exists stand in their own “god of the gaps” void.

This topic should be approached on two other grounds, one requiring an even more metaphysical level but will keep with the same notion of cause, and another applying this causality to the Argument From Motion for the sake of illustration (and perhaps to offer an explanation as to why some philosophers conclude Aquinas’ Five Ways aren’t really five ways since some are reducible to very similar arguments).

It is the nature of philosophy that even the lowliest of philosophical ponderers must apply a name to every idea, and being unable to resist the temptation, the first I will refer to as a Causal Argument of Sets. In logical form, suppose we state the whole of causality as cause and effect, with its temporal considerations intact in this manner:

{…c, e, c, e, c, e,…}

Within the brackets is represented the law of causality, cause, and effect, to infinity. Such an illustration might serve as an answer to someone who challenges, despite arguments of First Cause, it is so that causality has extended both into the past and into the future ad infinitum. Hence, a possible utility for this argument will be expanded on.

As mentioned, this is an obvious natural law. No phenomenon exists where someone doesn’t seek out a cause, know the cause, or suppose a cause. Psychologists have found causal relations in the mind, physicians within the body, and sociologists among trends and factions of society. The philosophy of determinism supposes causality in nature, in action, or even, in choice and thought. It seems this law is accepted on all fronts to some degree. In fact, I suggest there is no reason to declare otherwise when considering time itself. A moment in time, no matter how brief and minuscule, is dependent on time existing prior, and thus every current moment is in essence an effect with time prior being the cause. In a way, the effect of tomorrow depends on the cause of today.

As the Greek playwright Sophocles wrote:

“If anyone counts upon one day ahead or even more, he does not think. For there can be no tomorrow until we have safely passed the day that is with us still.”

–Sophocles. (1966). The Women of Trachis and Philoctetes. Translated by Robert Torrance. Houghton Mifflin

At any rate, is it reasonable for one to assume such a law sprang from nothing in and of itself or would be subject to the same principle found within the causal set? While there are many theories where the relationships within the set are not found necessarily outside the set, a metaphysical and philosophical law implies universality and if causality is found in certain things and not others it is not a metaphysical law. Thus, if this law, or any law, is said to exist, then it is bound by the same cause/effect relationship found within the set, and a First Cause is needed. This might be expressed as:

C -> {…c, e, c, e, c, e,…}

We simply restate this by saying there needs to be a Cause for causality. Interestingly, it becomes clear to see the attributes of God which the Bible attests to. Aquinas surprises by not only seeking to show God’s existence but His necessary attributes as well, for without them, nothing that was made could have been made, as the scriptures tell us:

John 1:3, “All things were made through Him, and without Him was not anything made that was made.”

It seems apparent, just like in Aquinas’ argument from motion, an infinite regress within the universe is impossible and the set needs to begin with a cause:

C -> {c, e, c, e, c, e,…}

It is impossible for a First Cause to produce the universe by effect at the beginning within the set, like so:

C -> {e, c, e, c, e, c,…}

This would not bring about anything since it is of the nature of things that cause brings about effect, while this would assume the opposite. This is where we can apply the former reasoning of the Aquinas’ First Way. An effect standing alone in the universe, if we could even accurately apply the term to begin with, is nothingness. It is only potentiality since an effect may be realized or not and could or could not be dependent on the existence of the former cause. Effects are not impossible things, nor are they necessary things, but are potential things. Thus, the building blocks of the universe could not have been made from potential effects, but from actuality. We apply the reasoning of actuality to potentiality in the Argument From Movement to cause and effect, with cause being actuality, and effect being potentiality. As actuality is the necessary condition for potentiality, so too is cause the necessary condition for effect. If there is no actuality or cause, there is no effect or potentiality.

Therefore, by our flowchart from before, it fits to put cause and effect in the place of, or alongside, actuality and potentiality. It is seen the First Cause could not have brought effects into proper being, but causes. Multiple causes must exist from the onset of the universe so that by their interaction the effects are made manifest and causality is put in motion as a universal law or first principle.

The set illustration helps us solve an additional problem we might face. If there is a First Cause then it is the case the universe is an effect, but cannot be started as an effect with its own laws, since it would need to exist before itself. Further, if the universe is an effect, it too is potential, but if it is a potential effect then it could not have been or could be. This leads reasonably well into the arguments for the need for the Personality of God, adding to the attributes Aquinas has already alluded to. A personal Being, of Pure Being, who made the choice to cause the universe to be. He is timeless, the Creator, and is Personable since the whole of the universe is only a potential effect.

With these considerations in place, our set may look like:

C -> E(c, e, c, e, c, e…)

What about God? Doesn’t this illustration leave room for God to be an effect? No, the First Cause (and True Actuality) would need to be timeless, which this model implies. True beginnings are not needed outside time, for there is no cause/effect relationship outside time since nothing can come before, nor after. Now doesn’t the universe being an effect imply time outside of the set, and thus both the First Cause and the effect of the First Cause are within time? Yes, but not in the same way we perceive it within the causal timeline set of the universe. The effect includes time within it. There is such a thing as meta-time or, say, a heavenly time, but by definition, it would have to differ and be more complete than our perceptions of time within our timeline.

We can see this by our inclusion in the causal set of the universe, which regulates us to being once removed through causality and kinship from the First Cause. This differs from the heavenly things inasmuch as they are created directly by the First Cause and owe their existence directly to God without a vast chain of regress. It is salvation that God uses to take man from being once removed to being in direct relation to Him by the eventual resurrection and renewal of all things through which God wants to bring back all removed from him. The Scripture makes clear the difficulty of the human mind in contemplating time as it refers to both the heavenly things and the true Eternal God.

Ecclesiastes 3:11; 14-15, “He has made everything beautiful in its time. Also, he has put eternity into man’s heart, yet so that he cannot find out what God has done from beginning to end….I perceived that whatever God does endures forever, nothing can be added to it, nor anything taken from it. God has done it, so that people fear Him. That which is, already has been; that which is to be, already has been; and God seeks what has been driven away.”

“God seeks what has been driven away,” refers not only to original sin but the whole of the universe which currently stands as once removed that through the renewal of the world and the resurrection of man, all things will owe their being directly to God and be united in His presence once more.

Through the explorations of causality and movement themselves, the need for actual things and causes to be at the onset of the universe is clear. The set starts with multiple causes to bring effects into being. So there is no infinite regress of time. On the meta-level however, there are not multiple causes that need to exist to introduce effect, but a singular Cause for their being. Since this Cause must embody Being itself to impart being, as shown in the Argument From Motion, it extends to infinity both toward, say, the meta-past and forevermore. Among heavenly things, all point directly to God without the need for intermediate causes.

But who can fully understand?

2 Peter 3:8, “But do not overlook this one fact, beloved, that with the Lord one day is as a thousand years and a thousand years as one day.”

The fifth-century Bishop of Ravenna highlighted the mysteries that confront us when he said:

“With God, beings who will be born are already born; with God future things have been made.”

–Peter Chrysologus

Another theologian wrote:

“We only see the system of Providence in the making, and not as a completed whole. Therefore, we can only discern the mere rudiments of what shall be; no complete or extensive knowledge being possible to us….We can only see, at a time, but an inconsiderable part of the ocean, so that we can never take a view of it as one great whole. In like matter the ways of God can only be seen in small portions. Their vastness overtakes our powers. Eternity casts upon the whole course of time the shadow of mystery. We have enough light to work by, but not enough for complete revelation. The creature of a day cannot be expected to grasp those vast designs stretching from creation to the final destiny of all things.”

–Thomas Henry Leale

There is only one sense where the existence of meta-time would lead to an infinite regress of causality, but only if we regarded meta-time, the time found among heavenly things, as the means by which our own timeline came into being. This is not what Judeo-Christian doctrine declares, as has, hopefully, been shown in this exploration.

As we contemplate a First Cause, a thing comprised of Being itself, then we have no infinite regress and this First Cause extends or exists unhindered by time and apart. It is fascinating to reflect on this as applied to Exodus 3:13-14, as God reveals Himself as “I AM,” which can be indicative of the attribute of God’s nature of being Pure Existence. Philosophers and theologians have long pondered the essence or the substance of God, and most, quite rationally, say it is unknowable. Yet, I posit, in part, God’s essence is one of Pure Being.

Exodus 3:13-14, “Then Moses said to God, ‘If I come to the people of Israel and say to them, “The God of your fathers has sent me to you,” and they ask me, “What is His name?” what shall I say to them?’ God said to Moses, ‘I AM WHO I AM.’ And He said, ‘Say this to the people of Israel: “I AM has sent me to you.”‘”

Jesus refers back to His divine timeless nature when he addressed the Jews in John 8:

John 8:58, “‘Very truly I tell you,’ Jesus answered, ‘before Abraham was born, I AM!'”

To simplify all created things must exist in time to some degree since there can be no subsequent or prior without time, and if the created heavenly things and beings were not created, then they would share a place with God which cannot be. So either set, whether in meta-time or our timeline, are ultimately dependent on a timeless First Cause though they differ regarding the presence of intermediate causes.

Can’t it be said the spark that set off the Big Bang existed outside time too? It can, but ironically enough for those who use this argument, it appears it was borrowed from theists, and clearly points to a supernatural origin of the universe. The strict philosophical materialist and the naturalist would be hard-pressed to admit the existence of such a supernatural origin, which is why, I suppose, this argument isn’t very popular, though it does spring up from time to time. It is far from being prominent, however.

Going back to The Causal Argument of Sets, it does one last thing by implying any law which is found in nature, must have been given or impressed upon nature by a Law-Giver. As we see causality as a law within the timeline set, we can fill the brackets with any law you please, laws of mathematics, logic, physics, gravity (as one physicist said laying all of existence at its feet), etc. These universal laws must be attributable to some cause, which denotes the intelligence found in the First Cause. The attributes of omnipotence and omnipresence aren’t ruled out either in the Causal Argument of Sets but are suggested or implied by more thought exercises.

To close out it suffice to say the first two of Aquinas’ ways do rather well in prompting us to behold some of God’s ways.