AN INTRODUCTION TO THE FIVE WAYS OF ST. THOMAS AQUINAS
Where better to begin than a discussion of the famous “Five Ways” of St. Thomas Aquinas? Thomas was a thirteenth century Dominican friar (1225-1274). His Five Ways are included in Part I of the Summa Theologica, his great unfinished masterpiece, written as a primer for students of the Christian religion. The format of the Summa is: question, objections, answers. Thomas proposes a question, lists a series of objections, then answers those objections. For instance, Thomas asks, “Whether it is possible to demonstrate the existence of God?” He then presents three objections to the position that it is possible to demonstrate the existence of God. He then answers those objections, concluding that it is, indeed, possible to demonstrate the existence of God. This is Thomas’ pattern throughout the Summa.
Thomas’ Five Ways have often been misrepresented because they are so often misunderstood. Many of the objections to the Five Ways are based on a misreading of them. Too often, contemporary philosophers misapply modern concepts to Thomas’ thirteenth century arguments. Often enough, however, misunderstandings are based on a difficulty in following Thomas’ reasoning. The Fourth Way, in particular, has stumped many highly intelligent thinkers, both Catholic and non-Catholic. They admit that they simply don’t understand it. Though some are easier to follow than others, even for the non-philosopher, anyone who claims that Thomas’ Five Ways are easily understood or, even more telling, easily countered, likely fails to understand them. I’ve made an effort to make Thomas’ Five Ways as understandable as possible. While I hope I haven’t failed, I don’t boast prematurely.
Can it be Demonstrated that God Exists?
Before considering Thomas’ Five Ways for demonstrating the existence of God, let’s look at how Thomas concludes that it’s even possible to demonstrate the existence of God, for we’ve seen that the possibility of demonstrating God’s existence isn’t held by all. Thomas lists three objections to the notion that God’s existence can be demonstrated:
- God’s existence cannot be demonstrated because His existence is an article of faith. Articles of faith cannot be demonstrated because faith is faith in what cannot be seen (Hebrews 11:1), whereas what can be demonstrated can be seen. Since God cannot be seen, His existence cannot be demonstrated;
- God’s existence cannot be demonstrated because we cannot know God’s essence. As such, we can only say what God is not (ie: God is not the universe, God is not a superhuman, etc…), but we cannot say what God is, because the essence of an infinite God is impenetrable to finite human beings;
- God’s existence cannot be demonstrated because whether or not He exists can only be known by His effects, or His impact on the world around us (somewhat like knowing the wind is there by seeing the trees and grass bending). But, God’s effects on a finite world are themselves finite, whereas God is infinite. So, His effects are insufficient to demonstrate His existence, because what is finite cannot possibly suffice to demonstrate what is infinite. Infinity is simply too vast and incomprehensible to be explained by the finite.
Thomas then turns to Romans 1:20, where St. Paul insists that the “invisible attributes” of God can be seen in what He has made. So, we can demonstrate the existence of God by looking to what He has made. Thomas explains that there are two ways to demonstrate something: to begin with the cause and move forward to the effect, or to begin with the effect and move backward to the cause. He then says that demonstrating the existence of God is an example of the second way: since the effects of God are those things we can observe, we can start there and move back to the cause, where we find God.
An example: a man is sitting at his kitchen table reading the newspaper when he hears a loud crash in the living room. Rushing there, he finds bits and pieces of glass covering his couch and all over the coffee table and carpet. He also finds a baseball on his living room floor. He looks out the window and sees no one around, only the scenery of his neighborhood on a bright, lovely summer day. Does the man conclude that the window shattered itself? Of course not! The evidence (hole in the window, glass all about and a baseball on the floor) points from the effect (the shattered window) backward to the cause (someone or something hurled the ball from outside the house through the window). Does he know who or what hurled the ball through his window? No. But, he knows someone or something did. Balls don’t hurl themselves about, occasionally taking out a window.
Another example: a woman is sitting on a park bench, reading a book and enjoying a brisk autumn afternoon. She hears just in the distance a stirring rendition of “Ave Maria” on the violin. She listens and enjoys. After the music stops, she looks about to see from where the music came. She sees a gazebo, now empty save but a music stand and a violin box. Does she know who was playing the music? No. But, she knows someone was playing. Violins don’t just pick themselves up and start playing on their own.
We can look at the effect of Creation and conclude backwards from the effect to the cause: someone or something created this, just as something or someone created the broken window and someone created the strains of “Ave Maria” on the violin. Can we know all about who or what did the creating? No. The evidence doesn’t reveal enough to say so. But, we can know that someone or something created all of this. Universes don’t create themselves; neither do they go back infinitely (more on these two critical points later). Just as there must be a cause for the baseball having passed through the window and for the strains of the violin playing softly the “Ave”, or the effect wouldn’t have happened and wouldn’t now be seen or heard, so there must be some cause to the universe, otherwise the universe wouldn’t be here for us to experience.
Thomas replies to the first objection (that the existence of God is an article of faith), and rejects it. There are qualities of God that can be known by natural reason, by deduction. These qualities of God are not articles of faith, but faith is built on top of them. The most basic quality of God we can come to know by natural reason is the fact of His existence. We may not know much about whoever or whatever caused the ball to fly through the window, yet we can certainly know that he or she or it exists. Just so, we don’t require faith to conclude that God exists. Reason is sufficient to conclude for the existence of God. Faith, then, is what we believe about the God Whose existence reason demonstrates.
The second objection (that we cannot know God’s essence) falls for the same reason. Existence precedes essence. We don’t need to know the essence of a thing in order to know it exists. Rather, just the opposite: we must first have knowledge of a thing’s existence before we can hope to know its essence. What caused the ball to fly through the window? A boy? A girl? A playful pooch? The wind? We don’t know. But, whatever it is, we know it exists. Who is responsible for the music we hear in the park? A man? A woman? A maestro or an amateur? We don’t know. But, whoever it is, we know he or she exists. Further investigation can then answer the question of essence.
Finally, the third objection fails for the same reason: we don’t need to know everything about a cause in order to know that the cause exists. The finite can never completely reveal or explain the infinite. But, that isn’t the same as saying that the finite can say nothing of the infinite. A dog is much more complex than the wind, and a boy much more complex than a dog. The effect can’t always tell us much about the complexity of whatever caused it. But, it can point to at least one attribute: existence. Again, we don’t need to know everything about a cause, even an infinitely complex cause, in order to know some things. What we can certainly know about a cause through its effects is the existence of that cause.
Objections to the Existence of God.
Thomas begins his inquiry on whether God exists by listing two objections. These are the two classical objections of atheism to the existence of God:
- There is evil in the world. But, if God is God, than God is infinitely good. It is not possible that evil would exist in a world created by a God that is infinitely good. Therefore, God does not exist;
- All that we see in the created order can be explained by natural causes or human causes. So, we do not need to postulate the existence of God in order to explain it. This is known as the principle of parsimony, which later became known as Ockham’s razor (after William of Ockham, 1287–1347, an English Franciscan friar, philosopher and theologian). Basically, Ockham’s razor claims that, if something can be explained using fewer assumptions, there’s no reason to introduce more. The simpler the better. If the creation of the universe can be explained by natural means, there’s no reason to conjure the existence of a Supreme Being responsible for it all. If the shattered window can be explained by naughty boys batting balls into people’s living rooms, there’s no reason to be concerned that the world is being invaded by ball-wielding Martians intent on destroying peoples’ homes one window at a time. While Thomas addresses these objections in the Summa Theologica after presenting his Five Ways, for clarity I will present his replies to these objections here.
Reply to the First Objection:
Recall that the first objection is that God cannot exist because evil exists. If God existed, He would necessarily be good. But, if God is good, He would not allow for the existence of evil. Evil exists, therefore, God does not exist. Here, Thomas turns to St. Augustine of Hippo, the great Church patriarch of north Africa. Augustine says that since God is the highest good, He wouldn’t allow evil to exist unless it was to bring about some good from the evil. This is central to Christian theology, of course, for the greatest example of God bringing good out of evil is the sacrifice of Jesus on the cross, an evil act that won for us our salvation. Non-believers may not be so easily convinced. The atheist, however, must ask him or herself the question: Is it really impossible for evil to exist in a world created by a good God? Are the two mutually exclusive? Many may be confused or angry over the existence of evil in a world created by a good God, but it’s a difficult argument to make that the existence of the two in the same reality is impossible. I, for one, can think of a number of reasons a good God may tolerate the existence of evil: free will and the desire for a genuinely loving relationship with His people is the classic reason. Love not freely given isn’t love at all. Yet, love freely given necessarily means the possibility of love not given. In the end, even the atheist must concede that concluding in favor of the non-existence of God contributes nothing toward the non-existence of evil. Evil is here to stay, sadly. Essentially, the only difference between the long, dark tunnel in which the atheist finds himself, and the long, dark tunnel in which the believer finds himself, is that there is a light at the end of the believer’s tunnel called “hope”. While many atheists would see it as nothing more than a coping mechanism, believers find great solace in the promise that, if evil can’t be eliminated, it can be conquered and even redeemed. But, only if God exists, and only if He is good.
Reply to the Second Objection:
The second objection is that, since everything that exists can be explained by natural causes or human causes, we don’t need God to explain the existence of anything. Thomas answers by pointing out that there’s at least one thing in nature than cannot be explained by natural or human causes: all things in nature that act toward a final end do so regularly, that is, “always or almost always” (see, Lesson 6: The Argument from Final Ends). It is this regularity that must be explained, not the randomness that we also find in nature. Thomas explains that this regularity, this purposeful acting toward final ends, must be “directed by a higher agent,” One Who is not directed by any other. Otherwise, if everything could, indeed, be explained by natural causes, we would have no regularity at all, only random, haphazard ends, as we might see in the pattern of sand dunes created by the wind, or the pattern of rocks at the foot of a mountain after an avalanche. That’s not what we observe in the natural order, however, and the regularity we do observe must be explained somehow.
Thomas shows that the existence of God is not only the best explanation for the regularity we observe in nature, but the only explanation. Why? Could not the process of evolution, of natural selection, explain the regularity we see in living things? Just the opposite. The process of natural selection presumes the regularity in nature. Consider that long-necked giraffes survived while short-necked giraffes died out, because the long-necked giraffes could reach the vegetation at the top of the trees that the short-necked giraffes couldn’t. But, their survival depends on the regularity of long-necked giraffes mating and producing other long-necked giraffes, and not short-necked giraffes. If the result of mating was random-necked giraffes, there could be no such thing as natural selection. So with all living organisms. As well, natural selection can’t explain the regularity in non-living objects, such as the boiling point of water, the creation of water molecules from two hydrogen and one oxygen atoms, and the orbits of the planets and other celestial bodies. Can the laws of physics explain such things? Possibly, but laws describe reality, they don’t create reality. Natural and human causes utterly fail in explaining the ultimate origins of all that exists, never mind why there is something rather than nothing. These are philosophical questions. In answering these questions, philosophy turns necessarily to God as the final end of all.
One God or Five?
Do the Five Ways point to one God, or is it possible that they point to five different Gods? For Thomas, it’s impossible that there’s more than one God, and his Five Ways demonstrate this. For there to be more than one God, all the “Gods” would have to share the same essence while having their own distinct existence. But, God is that Being in Whom essence and existence are identical. God is being. God is existence. It’s not possible for two beings whose essence is existence to share an essence but not share an existence. Likewise, it’s not possible for essence and existence to be identical in two beings. Two beings can’t share the same essential identity in every way, for to do so would mean that there was no distinction between the two. If there is no essential distinction between two beings, nothing to differentiate one from the other, then that’s the same as saying that they are the same being, and only one.
As such, if there were more than one God, there would necessarily be some distinction between the two. This distinction, though, could only be the result of some perfection or privation that one possessed and the other lacked. But, God possesses all perfections and no privations, so the other being would simply fail to match up.
Finally, the order that exists in creation reveals a unity that can only be comprehended if there is unity in the cause of creation. There is one God.
Be Christ for all. Bring Christ to all. See Christ in all.