A Proof Of The Existence Of God

If recent surveys are correct, a growing number of Americans do not believe God exists. This is unsurprising. Most students today graduate from public high school with little or no introduction to philosophy. That is a shame. Most of the greatest minds throughout human history thought the existence of God followed from reason and observation of the natural world. Why?

One reason has its origins in Aristotle. It goes as follows. Change occurs in the world around us. Seeds turn into plants. Ice melts into liquid. Cold water becomes warm. What these changes involve is what Aristotle called the “actualization of a potential.” That is, before seeds are actually plants, they are potentially plants; before ice is actually liquid, it is potentially liquid; before cold water is actually warm, it is potentially warm. In other words, change involves things going from “potentiality” to “actuality,” at which point, Aristotle would say, their potential is “actualized.” Good. Now, as we will see, this leads to “pure actuality,” or God.

But to get there, consider how something goes from potentiality to actuality. When the water goes from potentially warm to actually warm, it does not actualize its own potential. Rather, to mirror an illustration from Ed Feser, its potential is actualized by, say, the warm air in the room. In turn, the air’s potential to be warm is actualized by, say, the fire in the hearth. And the fire’s potential is actualized by, say, the flame of the match you struck. In short, anything that goes from potentiality to actuality is actualized by another.

So far, so good, but now consider these changes. You light the fire, which heats the air, which warms the water. First, note that whatever causes something to go from potentiality to actuality must itself be actual. For instance, the match is actually (not potentially) struck when it lights the fire, the fire is actually (not potentially) lit when it heats the air, and the air is actually (not potentially) hot when it warms the water. Second, note that these changes occur in time (as we will see, not all change does). And finally, as Feser stresses in his own illustration, note that the later causes of change--the fire and the air--have intrinsic causal power. For example, after you light it, the fire has the power to warm the air all on its own, even if you drop dead. Similarly, once the air is warm, it retains power to heat the water, even if the fire stops. This, then, is an "accidentally ordered" series of causation. From a rational standpoint, a series like this could extend to infinity without a first cause.

To understand why, imagine a father who begets a son, who begets a son of his own, and he another, and so on. Like the air and fire above, each offspring has intrinsic causal power (to reproduce). Therefore, if each son has a son of his own, this chain could go forever. Furthermore, since it is as easy to project this trend back in time as it is forward in time, there is no rational basis why the series requires a temporal beginning, or a “first cause.” (In fact, it was on this basis that Aristotle believed the universe was eternal.)

Be that as it may, consider now another type of change. Imagine Shakespeare writing a sonnet. While in the examples above change occurred over time, here change happens simultaneously, or in a “downward” sense at a single moment in time. Consider, for example, the changes involved when Shakespeare moves his hand along the paper as he writes: The paper’s potential  

to be imprinted is actualized by the pen, while the pen’s potential to be moved is actualized by Shakespeare. In other words, the paper is imprinted as the pen moves which happens as Shakespeare moves it. Thus, although completing a sonnet takes time, the act of writing--ie, moving the pen along the paper--involves a series of simultaneous changes. Furthermore, notice that unlike the air, fire, and offspring above, the pen lacks intrinsic causal power. It cannot move itself. Rather, it derives the power to move from Shakespeare, without whom there would be no sonnet. A series like this cannot therefore go to infinity without a first cause. After all, an infinite number of pens have no more power to move themselves and write a sonnet than does a single pen. This, then, is an “essentially ordered” series of causation. Series of this type account for anything that exists, which leads to a first cause of existence, or “pure actuality.” Here is why.

While we have seen that change happens over time (the heating of the water, producing offspring) and at a particular moment within time (the act of writing a sonnet), consider how change also occurs to keep objects in existence. To be sure, maintaining something in existence is not typically considered “change,” but it nevertheless involves the actualization of potentials. Why? To borrow from Feser once more, all physical things--trees, dogs, bananas, water, etc.--are composed of matter. Since matter therefore has the potential to exist as any particular thing, or even as no particular thing, something must actualize its potential to exist in the way in which it does, at any moment that it does.

So, consider the wood from the hearth. What actualizes its potential to exist, here and now? One may answer that its existence is explained by the structure of its molecules. But the molecules have the potential to be organized differently, or even to decompose altogether (as when wood is incinerated), so what actualizes their potential to be held together in this way, at this moment? One might reply that the molecular structure is explained by the sequence of the subatomic particles. Yet the subatomic particles also have the potential to be combined differently, so what actualizes their potential to stay combined in this manner, here and now? Appealing to the sub-subatomic particles will not do, because they too have the potential to be arranged differently than they are, and yet they persist in the form of wood. Why?

What we have here is a series of causes that derive power from something else: The wood derives power from the molecules, the molecules from the subatomic particles, the subatomic particles from the sub-subatomic particles, and so forth. Therefore, this is an essentially ordered series of causation, which, as we saw, cannot go to infinity without a first cause. To repeat, an infinite number of causes here could no more explain the existence of the wood than an infinite number of pens could explain the writing of a sonnet. Ergo, there must be a cause that actualizes the potential existence of the wood without needing its own existence actualized by anything else. There must be, in other words, an uncaused cause--a cause with no potential for existence, but that simply is pure existence, or “pure actuality.” OK, but why call this cause “God”?

First, consider that as the actualizer of all existence, this cause transmits ongoing power to

sustain all things in existence. Therefore, it must be all-powerful, or omnipotent. Furthermore, since change entails going from potentiality to actuality, and because this cause as “pure actuality” has no potentiality, it must be changeless, or immutable. Now anything that changes exists within time, so something changeless must be timeless, or eternal. But then, if something is immutable and eternal, it must also be immaterial and therefore incorporeal. Additionally, notice that we are describing a cause, not multiple causes. Consider that for there to be more than one kind of a thing, there must be a differentiating quality or characteristic. For example, something might be tall or short, or brown or green, or strong or weak. But since this cause is immaterial and incorporeal, and because as pure actuality it lacks potentiality, there are no such differentiating features, nor could there be in principle. So, it must be one.

Now, although more follows from this analysis, due to space constraints we must close our inquiry here. Nevertheless, we have enough to see that the cause in question is omnipotent, immutable, eternal, immaterial, incorporeal, and one. To be sure, nothing said here sheds light on revelation or scripture, but it does reveal that this uncaused cause possesses the key attributes traditionally associated with God.

Of course, not everyone will agree. After all, few arguments compel universal assent, especially upon first engagement, and especially when they are truncated into essay form. However, inquisitive readers can find arguments like this more powerfully expressed from Michael Augros, John Haldane, Maurice Holloway, John McCormick, Gerard Vershcuuren and Ed Feser.

But to return where we began, it is one thing to know the arguments for God’s existence and to reject them, it is another to not encounter them at all. Given the de-emphasis on philosophy in public schools today, it is not unreasonable to suppose that most students do not encounter them. That is unfortunate. Young people ought to know why luminaries like Newton, Galileo, Descartes, Locke, Plato and Aristotle (to name but a few) believed that the existence of God was evident from reason and experience. More than that, they ought to know that life has meaning, and that philosophy can help uncover why.