The Five Ways of Aquinas

Saint Thomas Aquinas was one of the best scholastic philosophers of the Roman Catholic Church. Aquinas provided logical grounds for significant number of Catholic dogmas. Hence, he is considered as a doctor and one of the early fathers of the church. Like other scholastics, Thomas Aquinas used the Greco-Roman philosophy, particularly the Aristotelian logic, to provide rational foundation for faith. Aquinas greatest work was the voluminous Summa Theologica. In this work, Aquinas presented five logical proofs about the existence of God. These proofs are more commonly known as the quinquae viae or five ways.

Here is the summary of these so-called proofs:

I. First Way: The Argument from Motion

St. Thomas Aquinas, studying the works of the Greek philosopher Aristotle, concluded from common observation that an object that is in motion (e.g. the planets, a rolling stone) is put in motion by some other object or force. From this, Aquinas believes that ultimately there must have been an UNMOVED MOVER (GOD) who first put things in motion. Follow the argument this way:

1) Nothing can move itself.

2) If every object in motion had a mover, then the first object in motion needed a mover.

3) This first mover is the Unmoved Mover, called God

II. Second Way: Causation of Existence

This Way deals with the issue of existence. Aquinas concluded that common sense observation tells us that no object creates itself. In other words, some previous object had to create it. Aquinas believed that ultimately there must have been an UNCAUSED FIRST CAUSE (GOD) who began the chain of existence for all things. Follow the argument this way:

1) There exist things that are caused (created) by other things.

2) Nothing can be the cause of itself (nothing can create itself.)

3) There can not be an endless string of objects causing other objects to exist.

4) Therefore, there must be an uncaused first cause called God.

III. Third Way: Contingent and Necessary Objects

This Way defines two types of objects in the universe: contingent beings and necessary beings. A contingent being is an object that can not exist without a necessary being causing its existence. Aquinas believed that the existence of contingent beings would ultimately necessitate a being which must exist for all of the contingent beings to exist. This being, called a necessary being, is what we call God. Follow the argument this way:

1) Contingent beings are caused.

2) Not every being can be contingent.

3) There must exist a being which is necessary to cause contingent beings.

4) This necessary being is God.

IV. Fourth Way: The Argument from Degrees and Perfection
St. Thomas formulated this Way from a very interesting observation about the qualities of things. For example one may say that of two marble sculptures one is more beautiful than the other. So for these two objects, one has a greater degree of beauty than the next. This is referred to as degrees or gradation of a quality. From this fact Aquinas concluded that for any given quality (e.g. goodness, beauty, knowledge) there must be a perfect standard by which all such qualities are measured. These perfections are contained in God.

V. Fifth Way: The Argument from Intelligent Design

The final Way that St. Thomas Aquinas speaks of has to do with the observable universe and the order of nature. Aquinas states that common sense tells us that the universe works in such a way, that one can conclude that is was designed by an intelligent designer, God. In other words, all physical laws and the order of nature and life were designed and ordered by God, the intelligent designer.

At first glance, the proofs of Saint Thomas seem very convincing. However, these arguments are full of logical loopholes and inconsistencies. Saint Thomas was guilty of jumping into conclusions without any empirical support. Hence, it was comparable to jumping from an airplane without a parachute. However, he cannot be totally blamed for this. His way of thinking was just the predictable product of Medieval Catholic Church theological and psychological conditioning, which during that time was the most reliable form of "science."


Let me briefly discuss each argument:

I. First Way: The Argument from Motion

This argument has committed the logical fallacy known as begging the question. This argument posited more questions than answers. Aquinas concluded that the first mover must be God. However, what motivated God to make the first move? Although motion cannot have infinite regression, this argument assumed that God had been either not moving from infinity or he has been moving ever since. What then is the source of his energy? If nothing can move itself, how then God was able to move himself?

Cosmologically, it can also be equally valid that an impersonal, unconscious force or energy was the first unmoved mover. For instance, according to the Big Bag Theory, all motions, space, energy and matter can be traced back to a singularity at the beginning of the universe. This theory is supported by measurable and verifiable parameters such as the rate of expansion of the universe and the distances between galaxies.

II. Second Way: Causation of Existence

Saint Thomas Aquinas was partially right into thinking that anything that exists is caused by another. In this argument, he again used the assumption that there could be not infinite regression of causes. However, if this assumption was correct, then what caused God to exist? If nothing can cause itself to exist, how was God able to cause himself? If God has been in existence from infinity, what is the problem with a universe that has been in existence from infinity? This latter assumption is equally logical but much simpler and more probabale. Remember the basic equation of Einstein?

E=mc²

This equation implies that matter can be converted into energy and energy can be converted to matter. It is logical to suppose that matter and energy have always been in existence. The universe as we know today might just be one of the many manifestations of the changes in matter and energy. On the other hand, apparent self-causation has been observed in sub-atomic particles in laboratory settings.

III. Third Way: Contingent and Necessary Objects

In this argument Saint Aquinas made the distinction between contingent or potential beings and necessary or actual beings. However, modern physics has demonstrated that there are really no strict definitions of such things. In a universe of probability and chaos, things may exist without necessarily being dependent of other things. On the other hand, as demonstrated by Einstein's equation, matter and energy are mutually dependent from each other. Hence, their contingency and necessity are reflexive.

IV. Fourth Way: The Argument from Degrees and Perfection

In this argument, Saint Aquinas attributed all positive absolutes to God as the standard for all things. But it can also be logically possible that God is the absolute perfection of evil. For instance, if there are degrees of cruelty, then God must be the cruelest being. If there are degrees of insanity, then God must be the perfectly insane being. Hence, the so-called standard of "perfection" can be applied to both good traits and bad traits simply because these traits have gradations or degrees of perfection.

V. Fifth Way: The Argument from Intelligent Design

This argument is also known as the teleological argument. This argument is also expounded on the watch-maker argument. The argument from design is used by theologians and fundamentalist preachers as the best argument for the existence of God. This argument has even taken the form of the so-called "creation science." However, this argument is scientifically and logically false.

Although the universe is admittedly complex and intricate, it does not necessarily mean that it requires a designer. Comparing the universe and biological systems to human-made objects such as a watch is committing a logical fallacy known as false analogy. The way the universe and biological systems operate is very different from the way man-made objects operate. If a complex object needs a creator or designer, what could be more complicated than a super-intelligent, all-powerful God? Who then created God?

Contrary to the assumption of an intelligent and purposeful designer, the universe and biological systems exhibit randomness and probability. If the universe and biological systems were purposely designed, then they must not have any superfluous traits.

This fifth argument is addressed and refuted by the Theory of Evolution. This argument deserves more detailed discussions. Hence, I will post a separate article for this.