What are the Five Ways of Thomas Aquinas?

Answer

The Five Ways of Thomas Aquinas are the main rational arguments used by Aquinas to justify the existence of the Christian God. Although the Five Ways are frequently referenced in historical and philosophical discussions, they can be easily misinterpreted. Critics have tended to either over-complicate, oversimplify, or misinterpret Aquinas’s intentions with these arguments. His true purpose was to present a general, objective, rational argument for the existence of God based on commonly observable phenomena.

One common error is assuming that Aquinas meant for the Five Ways to provide a comprehensive, foolproof argument for God’s existence. In reality, he saw them as just the starting point, a way to establish the existence of God for those who sought reasoned and observable arguments. Therefore, it is more accurate to consider the Five Ways as an initial exploration of the concept of God’s existence rather than a complete representation of Christian theology.

Conversely, some critics oversimplify the Five Ways, often leading to misinterpretations. Aquinas wrote his works in the 13th century, so the terminology he used differs subtly from modern language. For example, when Aquinas referred to “motion,” he meant it in the sense of “change,” not physical movement. Understanding the Five Ways requires careful examination of Aquinas’s original intentions when presenting the arguments. Approaching the statements in a simplistic manner or without considering Aquinas’s broader philosophical context is unjust and can lead to misunderstandings.

There are various approaches to presenting Aquinas’s Five Ways. Despite their (relative) simplicity, each of these five arguments can be analyzed, nuanced, and debated extensively. To facilitate discussion, the main assertions can be summarized as follows:

I. The Argument from Change (“Motion”)

Change is readily apparent in theIn the universe, things move from a “potential” state to an “actual” state. However, this potential is for something that does not yet exist and thus requires something else to actualize it. Whatever actualizes that, in turn, must be actualized by something else. Logically, this chain of changes cannot be infinitely long, or else nothing would have ever changed in the first place. Therefore, there must exist some unchanged and unchanging thing that actualizes all other changes. This principle is not related to time or a sequence of events. Instead, it highlights the necessity of having something capable of causing the changes we observe: God, the Un-Moved Mover.

In other words, the first of Aquinas’s arguments for God’s existence emphasizes that all changes result from some other change. However, this chain of changes cannot be infinite, so there must be some unchanged (unmoving) thing (an unmoved Mover) that is ultimately responsible for all other changes (motion).

II. The Argument from Causality

Cause and effect are evident in the universe. Every occurrence is caused by something else. All events depend on some other occurrence or thing to happen. A thing cannot cause itself, or it would never come to exist. Logically, this chain of causation cannot be infinitely long, or nothing would have come to exist in the first place. Therefore, there must be an uncaused thing that causes all other things. This argument is not related to time or a sequence of events. Instead, it acknowledges that all things depend on something else for their existence.

In other words, the second of Aquinas’s ways to demonstrate God’s existence is based on the fact that all effects are caused by some other event, which in turn is the effect of some other cause. However, this chain of causality cannot be infinitely long, so there must be some uncaused cause: God, the First Cause.

III. The Argument from Contingency

Nothing

We observe in the universe is necessary; nothing needs to exist, in and of itself. We often observe things that cease to exist, falling victim to death, destruction, or decay. Eventually, all non-necessary things cease to be. But, if it were possible for everything to cease to exist, and if there has been an infinite amount of past time, then all things would have already ceased to exist. There would be nothing left at all. The fact that anything exists at all, even now, means there must be one thing that cannot cease to exist, one thing that must necessarily exist. There must be one thing that is non-contingent—i.e., its existence is not dependent on anything else. This thing must be.

In other words, Aquinas’s third argument or way to prove God’s existence is that, if everything were impermanent, eventually everything would cease to be. Therefore, there must be at least one thing that must, necessarily, exist (one non-contingent thing): God, the Necessary Being.

IV. The Argument from Perfection

Every trait we see, in every object, is compared to some standard: health, morality, strength, and so forth. The fact that we instinctively see degrees in these areas implies that there is some ultimate standard against which to judge that property. And all comparative properties share a common sense of “perfection.” This means there must be some ultimate standard of “perfection” from which to judge all other properties; those objects cannot be the source or definition of that property in and of themselves.

In other words, Aquinas’s fourth argument in favor of God’s existence points out that, in order to speak of “goodness” or “power,” we must have an absolute standard against which to judge those terms; there must be some other thing from which they ultimately derive that characteristic: God, the Ultimate Standard.

V. The Argument from Purpose

Many things in the universe “drive” toward a particular end, not random results. Magnets “drive” to seek metal or to align the

Ir poles. Seeds “drive” to become adult plants, not animals. This regularity, as opposed to randomness, is a sign of purpose—of intention or intelligence. However, magnets and seeds and such have no intelligence of their own. Therefore, their “drive” must be the result of some external intelligence setting or fixing or designing their behavior. In some means or mechanism, all purposes and functions must originate in some intelligent entity.

In other words, Aquinas’s fifth way to show the existence of God involves the fact that inanimate matter and energy do not exhibit intelligence or purpose. When we see something unintelligent that appears to have some specific purpose or that fulfills some purposeful role, we must assume that thing to have been given that purpose by some other intelligence. Ultimately, this leads to God, the Grand Designer.

The Five Ways Today

As we can see, there are strong similarities between Aquinas’s Five Ways and many other common arguments for the existence of God. However, there are distinctions to keep in mind.

Aquinas’s first three arguments share a common theme: that causality, logic, and so forth lead to an inference of the existence of some deity. The most frequently used of these in the modern world is closely related to the second argument, causality, and is usually simply referred to as the cosmological argument.

Fundamentally, the fourth argument is almost identical to the ontological argument as presented by Anselm. Aquinas saw a distinction, however, as his focus was on the source of a thing’s existence. That is, Aquinas was arguing that goodness or power in some finite object can only come from some other, greater source. Anselm’s ontological argument, technically, is more focused on the generic concept of “perfection.” Still, it is not uncommon for Aquinas’s fourth way to be approximated as the ontological argument.

The fifth argument, also known as Aquinas’s teleological argument, is similar to the modern-day argument f

From Intelligent Design. However, Aquinas’s argument presumes that individual components have some form of drive or initiative in and of themselves. Intelligent Design, on the other hand, presumes that individual components (e.g., atoms or energy) have no particular purpose or function outside of an intelligent intervention. This distinction is trivial for most purposes today. Yet, strictly speaking, Aquinas’s fifth way is not the same as modern Intelligent Design.

Scholars continue to debate the validity of the Five Ways of Thomas Aquinas. Regardless of how useful one considers them in a modern context, their importance in the fields of theology and philosophy cannot be overstated. When properly understood as the “ground level” of a rational defense of God’s existence, they are useful tools.