Description
St. Thomas Aquinas’ best known work is his “Five Ways” of proving that God exists. Laid out in his masterpiece, the Summa Theologica, they are curt, informal, and hardly defended. Despite what many think, they are not even apologetics, as the Summa was a manual for priests. The “proper” use of the Five Ways is deepening the understanding of people who already believe in God. If you would like to read St. Thomas’ more “formal” apologetics, they are here in the Contra Gentiles.
Now, I always use this contingency argument if I’m trying to convince someone to believe. I find it the most straightforward and airtight argument for God’s existence. I’m writing this article for different reasons. First, because despite the fact that these wouldn’t be the default arguments I’d use to convince an atheist, I do think they’re sound, and can be used for that purpose, and are extremely useful for the purpose St. Thomas intended: catechesis. Second, because atheists have made a cottage industry out of misinterpreting these arguments, attacking the strawmen, and then deriding St. Thomas and – by extension – all theists who admire his work. Even some theistic commentaries on the Five Ways are inarticulate and only add fuel to the fire. So, this article is also an attempt to help rectify confusion.
My goal is to briefly present each argument and explain how they form one unified whole. This is not going to be a robust defense of each argument. Again, if you want airtight proof that God exists, see here.
The First Way
“The first and more manifest way 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 towards which it 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 needs be put in motion by another, and that by another again.
But this cannot go on to infinity, because then there would be no first mover, and, consequently, no other mover; seeing that subsequent movers move only inasmuch as they are put in motion by the 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 to be God.”
Explanation
The first step to understanding this argument is to understand the Aristotelian meanings of “potential” and “actual.” This is where most of the confusion around this argument comes from. People assume this is referring to some sort of Newtonian potential energy, but it is not. The distinction is a shorthand reference to the law of noncontradiction: a cup of coffee which is actually 75° is potentially 70° because it cannot actually be 75° and 70° at the same time. One might say that the cup is not actually any one temperature, but is the average of many molecules. Sure, but this only pushes the issue down to the molecular level rather than addressing it. The idea of potency and actuality is simply that no being can be in two contradictory states at once.
Now these terms should illuminate the Aristotelian meaning of the word “motion.” Again, this does not refer to some Newtonian concept of an object literally moving from point A to point B. “Motion” describes beings going from a state of potency to a state of actuality. That is, the coffee cup moving from hot to cold. Or a subatomic particle going from “not-emitted” to “emitted.”
With this understood, we can move on to St. Thomas’s next point. Nothing can actualize itself, for that would require being in the actual state prior to being in the actual state, which is obviously impossible. Thus, if a being is changing from potential to actual, it can only be by the power of another. The temperature of the coffee changes due to the air, and the air because of solar radiation, and so on. But if all beings required the motion of another to precede them, nothing could ever change! Imagine plugging a TV into a power strip, and then that power strip into another, and that into another ad infinitum – the TV would never turn on. So how is it that things actually change?
First, we must understand another distinction: per se and per aliud. When a being has a quality per se, it has it “of itself.” Imagine fire. Despite all of the inputs to a fire not being hot – oxygen, wood, kindling – fire is hot. Fire has heat “of itself,” part of its nature, not derived from some other thing. When a being has a quality per aliud, it has it “of another.” So, if I use a fire to heat a pot of water, the water has heat “of another.” We’ve seen that anything moving from potency to act necessarily attains the actual state per aliud. This means the only solution to this infinite regress problem is a being which has actuality per se; a fully actual being with no potency, which moves potential beings to actuality without anything moving it, like fire heats without anything heating it.
Aquinas says that the fully actual being, or “first mover” must be God. He proves this in successive chapters; again, for a thorough explanation, see my argument here. For the purposes of this article, I will give a very truncated explanation:
There can only be one fully actual being, for any distinction from pure actuality is potency. A fully actual being cannot be material, because material always has potency – so He is immaterial. He must be eternal, for if He wasn’t, something would have to have moved Him from potential existence to actual existence. He must be perfect – that is, lacking in absolutely nothing, for any lack denotes unfulfilled potential. All things depend on Him, but He depends on nothing for His power, meaning He is omnipotent. He must be a mind, since an immutable immaterial actualizer can only express power through mind, not physical force, like how you can move your arm by power of mind; given this, He must know all things, for if He did not know something, He would have potential to know it. And so on and so on.
The Second Way
“The second way is from the nature of the efficient cause. In the 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 the intermediate cause, and the intermediate is the cause of the ultimate cause, whether the intermediate cause be several, or 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 of God.”
Explanation
The first step to understanding this deceptively simple argument is to understand “efficient causes.” There are two types of causal chains: accidental and efficient. An accidental series is a series of independent beings. For example, a man has a son, and then he has a son, and so on. These chains, St. Thomas allows, could go on forever. But an “efficient cause” denotes a simultaneous logical regression, in which each step continuously depends on the prior. For example: organs compose you, cells compose organs, molecules compose cells, atoms compose molecules, and so on. Unlike the accidental series, if you removed one step from this causal chain, the whole thing would fall apart. You can have a man with a dead father, but you can’t have an organ without cells.
Now, this argument simply points out that simultaneous regressions can’t be endless chains of causers deriving their power per aliud. Again, an infinite series of power strips could never turn on a TV. The answer to this infinite regression is the same as the previous one: something must have the power of cause per se, innate to its own being. And this, of course would also have be immaterial, immutable, eternal, and so forth – God. St. Thomas explains in the Contra Gentiles that God does not cause every single thing directly; rather, He is causality. That is, what causes a pot of water over a fire to become hot is the fire underneath it, not God; but the answer as to why the fire has that causal power – that is God, who has causality per se, who is causality itself.
The Third Way
“The third way is taken from possibility and necessity, and runs thus. We find in nature things that are possible to be and not to be, since they are found to be generated, and to corrupt, and consequently, they are possible to be and not to be. But it is impossible for these always to exist, for that which is possible not to be at some time is not. Therefore, if everything is possible not to be, then at one time there could have been nothing in existence. Now if this were true, even now there would be nothing in existence, because that which does not exist only begins to exist by something already existing. Therefore, if at one time nothing was in existence, it would have been impossible for anything to have begun to exist; and thus even now nothing would be in existence — which is absurd.
Therefore, not all beings are merely possible, but there must exist something the existence of which is necessary. But every necessary thing either has its necessity caused by another, or not. Now it is impossible to go on to infinity in necessary things which have their necessity caused by another, as has been already proved in regard to efficient causes. Therefore we cannot but postulate the existence of some being having of itself its own necessity, and not receiving it from another, but rather causing in others their necessity. This all men speak of as God.”
This phrasing is very confusing due to the standard English translation being poor. I have opted to use it in order to expose the issue.
Explanation
St. Thomas begins by pointing out that some beings are “possible” – that is, they are equally related to two contraries, being and not-being, as evidenced by generation and corruption. One common adjective for such beings is “contingent.” Since they are equally related to either of these contraries, we must seek an explanation as to why any possible being exists here and now.
Now the third and fourth sentences are critical, and the common English translation obscures their meaning. The argument seems to be that no possible being can exist perpetually, so something had to start the temporal sequence. But this is not the argument. The Latin better translates to: “but it is impossible for all things that exist to be such [possible], because what is possible not to be, sometimes does not exist. Therefore, if everything is possible not to be, then at one time there would have been nothing in existence.” So, the real point St. Thomas is getting at is that not every being can be merely possible, since that would mean everything is equally disposed to being or not-being, meaning all things are dependent on other things, which is an infinite regress problem. Again, it’s like the infinite power strips. This formulation aligns with the Contra Gentiles.
St. Thomas then moves to the next logical deduction: if not everything can be possible-contingent, something must be necessary. St. Thomas does not mean “necessary” the way some of his philosophical successors mean it. Necessary here means incorruptible, which does not exclude a necessary-contingent being – a being which cannot fail to exist once extant, but could have not existed to begin with. But if the explanation for possible-contingents is indeed a necessary-contingent, this just extends the infinite regress problem. There cannot be an endless chain of necessary-contingents passing along existence per aliud. So the only plausible answer is that eventually you reach a being which has existence per se, innate to itself. That is, one being’s nature must be “to exist,” it simply is existence. And this being, of course, would be necessary, uncaused, immaterial, immutable, eternal, perfect, and so forth.
The Fourth Way
“The fourth way is taken from the gradation to be found in things. Among beings there are some more and some less good, true, noble and the like. But ‘more’ and ‘less’ are predicated of different things, according as they resemble in their different ways something which is the maximum, as a thing is said to be hotter according as it more nearly resembles that which is hottest; 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, as it is written in Metaph. ii.
Now the maximum in any genus is the cause of all in that genus; as fire, which is the maximum heat, is the cause of all hot things. 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.”
Explanation
Despite how complex and archaic this one sounds, it is actually quite intuitive. St. Thomas begins with an analogy regarding fire. According to 13th century physics, fire is one of the four elements which constitute all things. Although this is obviously an outdated position, we can easily translate the argument to modern parlance by just using a different example, like salt. St. Thomas means to point out that only salt has saltiness per se, and if there were no being with such a nature, nothing else could have saltiness. As such, the entire genus (category) of saltiness depends on the existence of salt, the maximum. We can use plenty of other examples of this. The entire genus of wetness depends on water. Were there no water, there would be no wetness. The genus of redness depends on red. The genus of woodiness depends on wood.
Next, Aquinas points out that some things have more being than others, as a fox has more being than its shadow. But this means that “being” is a genus, which means it has a maximum – being itself, something which has being per se while all others derive being per aliud – namely, from this maximum, as all saltiness depends on salt. Aquinas then references Metaphysics II, in which Aristotle makes the point that “being” is interchangeable with other transcendental goods – truth is being insofar as it is intelligible; goodness is being insofar as it is desirable; perfection is being insofar as it is complete. So the maximum being is equally the maximum truth, goodness, perfection, and so on; and this, of course, is God.
Richard Dawkins famously quipped that if these premises are true, there must be something maximally stinky, and this would have to be God; Dawkins’ confusion likely stems from a lack of understanding of this last point leading him to think the genera St. Thomas associated with “being” were picked arbitrarily. But this is not the case. At no point does St. Thomas teach that God is the maximum of every genus. He teaches that God is the maximum of “being,” which carries with it the interconnected transcendentals.
The Fifth Way
“The fifth way is taken from the governance of the world. We see that things which lack intelligence, such as natural bodies, act for an end, and this is evident from their acting always, or nearly always, in the same way, so as to obtain the best result. Hence it is plain that not fortuitously, but designedly, do they achieve their end. Now whatever lacks intelligence cannot move towards an end, unless it be directed by some being endowed with knowledge and intelligence; as the arrow is shot to its mark by the archer. Therefore some intelligent being exists by whom all natural things are directed to their end; and this being we call God.”
Explanation
This is another one which sounds arcane, but is actually very intuitive. St. Thomas points out that things behave according to set patterns. St. Thomas calls this order to certain ends “final causality.” But final causality comes from intention, as the archer directs the unconscious arrow to its mark. Now acorns, for example, have a final causality of becoming trees. We know this because acorns don’t just become trees as random cosmic occurrences, but with a uniform, natural regularity. However, we also know that acorns are not conscious, which means something else must direct them to this final cause.
Many will point to evolution or the laws of nature as an explanation for this. But this objection misses the point entirely. If you came across a target with a hundred arrows in it, would “oh, the arrows are just following the law of flying into targets” be a satisfying explanation? Obviously not, since mindless objects do not “obey” laws at all. As C.S. Lewis put it, “to say that a stone falls to the earth because it’s obeying a law makes it a man and even a citizen.” So, again, assigning nomenclature to nature’s regularity does nothing to explain the trillions of proverbial arrows finding their marks. We obviously cannot explain nature’s regularity by an infinite regress of unintelligent coherers; rather we must posit that some universal governor has coherence per se, while all others have it per aliud. And this of course is God.
Conclusion
The Five Ways follow a series of chains which exhibit some property per aliud and trace them back to something which has the property per se. The first is actuality, which moves beings from a potential to an actual state. Since not all beings can be changed-changers without an infinite regress problem, there must be one being which is fully actual, actual per se, completely independent and self-sufficient. The second is causality, following likewise from the fact that not everything can be a caused-causer. Third is existence – since not everything can derive existence per aliud, one primordial being must have it innately. Fourth, being, since being is a genus, and all genera necessitate a maximum. Fifth, coherence, since there cannot be an endless chain of mindless coherers.
We see from the Five Ways that God is the alpha and the omega. He is the provider, and His provisions all lead back to Him as the ultimate final cause. “In Him we live and move and have our being” (Acts 17:28). In the Garden of Eden, Adam knew God by powerful intuition. He could look at a leaf falling and see God’s action in it, as we would see gravity in it. As I said, these arguments are not primarily apologetics; they are catechesis. They exist to make God a little clearer to all of us, like He was to Adam in the Garden.