The Existence of God According to Reason
In St. Paul’s letter to the Romans, we read: “Ever since the creation of the world his invisible nature, namely, his eternal power and deity, has been clearly perceived in the things that have been made” (Rom. 1:20). Here St. Paul sums up several passages of Old Testament wisdom literature (Wisdom 13:1-9, Psalm 19:1-4, Sirach 42:15-43:33). The wisdom literature affirmed that the existence of God can be known not only by the divine revelation to the chosen people, but also by human reason contemplating the world of nature all around us.
When this teaching was received by the Church, the early Christians observed that indeed there is a general consensus of the nations to the existence of some supreme Deity, and that some of the philosophers had offered arguments for the existence of God. As time passed, Christian theologian-philosophers then further developed those arguments for the existence of God and his attributes.
All of this has led the Catholic Church to teach definitively that “God, the first principle and last end of all things, can be known with certainty from the created world by the natural light of human reason” (Catechism of the Catholic Church, no. 36). In a world of much skepticism, this teaching can seem simply incredible. The purpose of this two-part essay is first to make several points about the nature and extent of the natural knowledge of God, then to offer a philosophical argument for the existence of God important for understanding the doctrine of creation and the meaning of evolution.
What, according to the Church, is the nature and extent of the natural knowledge of God?
The teaching on the natural knowledge of God is open to common misinterpretations. When the Church teaches that God can be known by the light of natural reason, she is not affirming that it is so obvious as to be undeniable to all people everywhere and at all times, that God exists. She is not teaching that the existence of God can be verified by the methods of modern sciences. She is not affirming that there is one special philosophical proof or argument out there that will convince all people everywhere to know that God exists. What, therefore, is the Church saying?
The Church is presupposing our earlier account of reason. Human reason is open to reality as a whole in all of its aspects, seeks something beyond all the scientific facts, seeks to know the meaning of all things, and is capable of such knowledge to some extent. Reason is wisdom seeking. The Church also understands that, like all natural or human forms of knowledge, the knowledge of God gradually develops both in the lives of individuals and in societies, and consequently there are higher and lower forms and degrees of the natural knowledge of God depending on the conditions in which human beings live and develop. And the Church understands that there are many obstacles to the development of the highest forms of the natural knowledge of God. For these reasons, widespread disbelief in the existence of God is consistent with the teaching that God can be known by the natural light of reason alone. For the natural light of reason, and especially the natural knowledge of God, can falter in adverse conditions of life.
What are some of the conditions that favorably or adversely affect the natural knowledge of God? Where there is intellectual aptitude, interest, time for contemplation, a tradition of inquiring into the existence of God, and a will to worship God once known, such as in some of the ancient philosophical schools, the natural knowledge of God grows stronger and develops in its higher degrees and forms. Where these conditions are lacking, the natural knowledge of God – at least in its higher forms – flounders or is even opposed. Furthermore, the Church acknowledges that because of the fallen condition of the human race, the natural knowledge of God faces special obstacles in its development:
Though human reason is, strictly speaking, truly capable by its own natural power and light of attaining to a true and certain knowledge of the one personal God, who watches over and controls the world by his providence, and of the natural law written in our hearts by the Creator; yet there are many obstacles which prevent reason from the effective and fruitful use of this inborn faculty. For the truths that concern the relations between God and man wholly transcend the visible order of things, and, if they are translated into human action and influence it, they call for self-surrender and abnegation. the human mind, in its turn, is hampered in the attaining of such truths, not only by the impact of the senses and the imagination, but also by disordered appetites which are the consequences of original sin. So it happens that men in such matters easily persuade themselves that what they would not like to be true is false or at least doubtful. (CCC, no. 37).
One could add that where skepticism about God, skepticism of metaphysics, or scientistic thinking, dominate the atmosphere, where the practice of cultivating natural knowledge of God has been rejected, where the tradition of learning it has been lost over the generations, or where a tradition of opposing it has been institutionalized and disseminated, widespread development of the higher forms of the natural knowledge of God is further impeded. For all of these reasons, one can say with St. Thomas Aquinas that if the human race were left to itself, without any special revelation from God, only a few people, after a long period of time, and still with an admixture of error, would develop the natural knowledge of God in its higher forms (Summa Contra Gentiles, Bk. I, ch.5). His statement illuminates our contemporary experience of the widespread cultural dominance of atheistic naturalism or physicalism.
In order to clarify further the nature and extent of the natural knowledge of God, let us distinguish between three degrees of cognitive development in the natural knowledge of God. One degree of development is pre-philosophical, a second is imperfect or rudimentary philosophical knowledge of God, and a third is perfect knowledge or rigorous philosophical demonstration of God’s existence. Each of these forms of knowledge differs in its intellectual sophistication and the extent to which it is found among human beings. The teaching that God can be known by the natural light of reason may thus be understood in terms of three claims:
- All human beings have a pre-theoretical knowledge of God. This sort of knowledge comes to be in all cognizant human beings more or less spontaneously as we live in and think the world. It is general and confused knowledge – so general and confused, so primordial in our experience, that one is not even necessarily even reflectively aware of knowing God. One knows God without realizing it, for one knows him by a name other than God. Aquinas describes two ways of having this pre-theoretical knowledge of God.
In the first way, St. Thomas Aquinas writes:
To know that God exists in a general and confused way is implanted in us by nature, inasmuch as God is man’s beatitude. For man naturally desires happiness, and what is naturally desired by man must be naturally known to him. This, however, is not to know absolutely that God exists; just as to know that someone is approaching is not the same as to know that Peter is approaching, even though it is Peter who is approaching… (ST I.2.1 ad 1; SCG I c.11)
All human beings are aware of goodness in general or have a notion of what goodness is – even if they cannot philosophically define goodness. It is the same with happiness. We all have a notion of it even if we cannot say what it is. Furthermore, all of us know that goodness and happiness are real. For we aim at them by nature, and expect our aim to succeed. Just by having the notion of what goodness is or what happiness is, and by knowing that goodness and happiness are there to be had, one knows God. We could say that one knows God by the name of goodness or by the name of happiness rather than distinctly as God. Aquinas compares this sort of knowledge to seeing someone afar off coming over a hill without knowing it is Peter coming over the hill.
A second way of having pre-theoretical knowledge of God is from world order. St. Thomas Aquinas writes:
For there is a common and confused knowledge of God which is found in practically all human beings; this is due…to the fact that… humans can immediately reach some sort of knowledge of God by natural reason. For, when human beings see that things in nature run according to a definite order, and that ordering does not occur without an orderer, they perceive in most cases that there is some orderer of the things that we see. But who or what kind of being, or whether there is but one orderer of nature, is not yet grasped immediately in this general consideration. (SCG III c. 38)
When human beings gaze upon the beauty, order, and harmony of the world as a whole, they commonly form the judgment that “there must be something behind it all.” In this knowledge, they know God by the name of something, but not yet distinctly as God. What that something is remains an open question to the inquirer, but one knows at a minimum that something is there to look into further.
Generally speaking, the pre-theoretical knowledge is deeply compelling, often virtually indefeasible in one’s mind, a powerful starting point of inquiry, recurring food for thought, and coupled with the innate desire to understand it could drive one to elaborate philosophical arguments for the existence of God as a way of trying to put into words what one knows in a more primordial way.
- Many human beings have an imperfect philosophical knowledge of God. Although we all start with a pre-theoretical or general and confused knowledge of God, human beings cannot be satisfied with it, for all human beings by nature desire to understand. And we are all fallen as well. Because we are driven by our nature to understand, many people unfold what they already know in a general and confused way into a clearer and more distinct understanding. Because we are fallen, however, human beings can also refuse or oppose this process of cognitive development and effectively deny at a higher level what we know at a lower level. For those open to knowing the existence of God more perfectly than in the pre-theoretical way, the process of cognitive development advances according to our differing intellectual aptitudes, various degrees of free time for thinking, and differing degrees of concern for intellectual penetration of the subject matter. Many people take first faltering steps at trying to articulate their general and confused knowledge of God in more theoretical statements and arguments.
Hence, it is common to come across popular arguments for the existence of God. Someone may say: “everything has a cause, but the causes can’t go back forever, so there must be a God.” Another may say: “whatever is designed has a designer, and the world is designed, so there must be a Designer.” These arguments represent first (or second or third) attempts to express some of the deepest intuitions of human reason about the ultimate meaning of all things. They are rudimentary philosophical arguments, and at whatever degree of sophistication they are developed they are open to easy refutation by someone with just a little more philosophical skill or to rejection by someone who is less astute at philosophy.
An objector may point out that if everything has a cause, then God too must have a cause, so the argument raises a problem for the proponent. Someone may point out that to say that the world is designed in fact begs a big question. Is the world in fact designed? Does not that claim presuppose the existence of God rather than prove it? In each of these cases, the objector may be genuinely more intelligent, or more thoughtful, or more philosophical, or more educated than the proponent of the argument for God. However, both sides can easily forget that a good argument can appear bad to one who is not very intelligent. In fact, most people – both proponents and opponents – of the existence of God are living and thinking in this second degree of development of the natural knowledge of God. Philosophical arguments for the existence of God, and objections to them, fall along a spectrum of philosophical sophistication and rigor. Rigorous philosophical demonstrations are for the few: the intelligent, the educated, and the dialectically skilled.
- A few people have a perfect philosophical knowledge of God. Here we would propose St. Thomas Aquinas has an example of someone who arrived at a radical and penetrating understanding of reality, and we offer two of his arguments for the existence of God for consideration. We ourselves acknowledge that our formulation and understanding of these arguments is subject to our own further cognitive development as we ourselves grow and seek to understand reality as a whole with greater insight and clarity. Rigorous philosophical demonstrations of the existence of God are, after all, one of the highest accomplishments of human reason, and it is likely that we still have some learning to do.
The first argument is from world order. Aquinas often mentions that the order, harmony, and beauty of the world is the starting point for all rational ascent to the existence of God. In one place (Summa Contra Gentiles, I.13.35), he offers an argument for the existence of God that we formulate and update in our own terms as follows:
- In the world of Nature, we find things of different natural kinds.
- The many things of different natural kinds each act in different and sometimes opposing ways.
- Even though the many things of different natural kinds act in different and sometimes opposing ways, the world of Nature is coordinated, harmonious, and ordered. (It is ecosystematic.)
- Therefore, there must be something responsible for the coordination and harmony of the many different things in nature.
Furthermore, it seems that nothing less than God, e.g. chance, the laws of nature, the four fundamental forces, or evolution, is a good candidate for that being which is responsible for the harmony and order of the world. We also find various stories about how the human mind “constructs” the order of the world to be epistemologically problematic and frequently self-defeating.
The second argument is from contingent being. The term “contingent being” here does not at first mean a dependent being. It means a being that exists but does not have to exist. Aquinas is well known for finding within contingent beings a real distinction between what it is and that it is, i.e. its essence and its existence. What a dog is and that the dog is right here and now, are not the same, because anything less than an absolutely simple being whose very essence is to exist.
An explanation of his argument best begins with a meditation on contingent beings. All around us we find many things that exist but do not have to exist: the sun, moon, stars, the plants, animals, human beings, even the earth itself. According to the best cosmology we have from physics, once upon a time these things – in fact, everything – did not exist, and so we know they do not have to exist. Each one essentially can fail at being.
When we ponder things that exist but do not have to, things that essentially can fail at being, the mind naturally asks why they exist at all. What gives them being or upholds them? With this question in mind, we formulate an argument from contingency as follows.
We can pick out any particular being, e.g. this dog here. It exists, but does not have to exist. What it is does not cause, account for, or guarantee that it is. Its own nature as a dog does not guarantee it exists or will continue to exist. At any one point in time throughout its journey in existing, the dog can fail to exist. So, its act of existing, that it is, must be received or supplied from without. It requires a cause of its very act of existing.
The parents of the dog are not the answer. The parents may be responsible for the dog coming to be but they are not responsible for the being of the dog here and now. This follows because the dog can continue to be even after its parents pass away. The cause of the dog’s coming to be, and the cause of its being, must therefore be distinct.
The matter of the dog is not the answer. The matter of the dog is just as much in need of a cause as is the dog, since the matter of the dog is the dog, and the dog is contingent. The matter of the dog is as contingent as the dog is. Furthermore, there is nothing about what matter is to guarantee that matter is. This holds both for particular bits of matter, even fundamental particles, as well as for matter in general. Therefore, there must be something outside the dog altogether that makes the dog to be.
Let us now ask about the cause of the dog’s being: Is that cause a contingent being? If so, then the cause too must have a cause, and we ask the same question. Is that too a contingent being?
We must arrive eventually at a non-contingent being that is a pure source of existing, something that does not receive its act of existence but only gives acts of existence to other things. Thus, we discover that it is impossible for one thing to receive existence from another without coming to a source or origin of existence.
The argument is even more radical when we consider Aristotle’s statement that cause and effect are simultaneous in act. Just as the mirror now reflects the light that now shines on it, so too, contingent beings now display the existence they are now receiving from the source.
We present the argument in the following form:
- Some beings are contingent beings.
- Every contingent being has a present cause of its very act of existing.
- It is impossible to proceed to infinity in a series of things each of which is the present cause of the very act of existing of the next.
- Therefore, there must be at least one being that presently gives the act of existing to (at least some) contingent beings presently existing, but is not itself contingent.
One last point is worth making. A non-contingent being could only be a being whose essence is to be. We cannot conceive of any other way for a being to exist necessarily. The argument thus arrives at Being itself giving being to beings around us.
This argument poses as many questions as it answers, and we are open to objections in order to grow in our own understanding of the truth.
One last question deserves to be raised: Why claim that either of these two arguments arrives at God? Why claim that the cause of all the order in nature is God or that the necessary being that gives being to others is God?
One answer is that the entity arrived at by both of these arguments matches the dictionary definition of God.
Another answer is that the Bible itself makes the connection between the entity arrived at in these arguments and the God revealed in the bible. In many places, the bible affirms that the one responsible for the order of the world is God (e.g. Wisdom 13: 1-9, Psalm 19:1-4, Sirach 42:15-43:33) and in one place the bible, at least traditionally understood, affirms that “I AM” is one of the names of God (Ex. 3:14). Traditionally, this has been understood to coincide with metaphysical arguments for the existence of God. The philosophers came to the God who also came to Moses.
— Rev. James Brent, O.P.