Twenty Arguments For The Existence Of God

(Dr. Peter Kreeft is a renowned Catholic apologists who teaches philosophy at Boston College. This is his compilation of twenty arguments for the existence of God. I have summarized the arguments below. They can be read in their entirety here.)

1. The Argument from Change 

Briefly, if there is nothing outside the material universe, then there is nothing that can cause the universe to change. But it does change. Therefore there must be something in addition to the material universe. But the universe is the sum total of all matter, space and time. These three things depend on each other. Therefore this being outside the universe is outside matter, space and time. It is not a changing thing; it is the unchanging Source of change.

2. The Argument from Efficient Causality

Even as you read this, you are dependent on other things; you could not, right now, exist without them. Suppose there are seven such things. If these seven things did not exist, neither would you. Now suppose that all seven of them depend for their existence right now on still other things. Without these, the seven you now depend on would not exist—and neither would you. Imagine that the entire universe consists of you and the seven sustaining you. If there is nothing besides that universe of changing, dependent things, then the universe—and you as part of it—could not be. For everything that is would right now need to be given being but there would be nothing capable of giving it. And yet you are and it is. So there must in that case exist something besides the universe of dependent things—something not dependent as they are.

And if it must exist in that case, it must exist in this one. In our world there are surely more than seven things that need, right now, to be given being. But that need is not diminished by there being more than seven. As we imagine more and more of them—even an infinite number, if that were possible—we are simply expanding the set of beings that stand in need. And this need—for being, for existence—cannot be met from within the imagined set. But obviously it has been met, since contingent beings exist. Therefore there is a source of being on which our material universe right now depends.

3. The Argument from Time and Contingency

Question1: Even though you may never in fact step outside your house all day, it was possible for you to do so. Why is it impossible that the universe still happens to exist, even though it was possible for it to go out of existence?

Reply: The two cases are not really parallel. To step outside your house on a given day is something that you may or may not choose to do. But if nonbeing is a real possibility for you, then you are the kind of being that cannot last forever. In other words, the possibility of nonbeing must be built-in, "programmed," part of your very constitution, a necessary property. And if all being is like that, then how could anything still exist after the passage of an infinite time? For an infinite time is every bit as long as forever. So being must have what it takes to last forever, that is, to stay in existence for an infinite time. Therefore there must exist within the realm of being something that does not tend to go out of existence. And this sort of being, as Aquinas says, is called "necessary."

4. The Argument from Degrees of Perfection

But if these degrees of perfection pertain to being and being is caused in finite creatures, then there must exist a "best," a source and real standard of all the perfections that we recognize belong to us as beings.

This absolutely perfect being—the "Being of all beings," "the Perfection of all perfections"—is God.

Question 1: The argument assumes a real "better." But aren't all our judgments of comparative value merely subjective?

Reply: The very asking of this question answers it. For the questioner would not have asked it unless he or she thought it really better to do so than not, and really better to find the true answer than not. You can speak subjectivism but you cannot live it.

5. The Design Argument

This sort of argument is of wide and perennial appeal. Almost everyone admits that reflection on the order and beauty of nature touches something very deep within us. But are the order and beauty the product of intelligent design and conscious purpose? For theists the answer is yes. Arguments for design are attempts to vindicate this answer, to show why it is the most reasonable one to give. They have been formulated in ways as richly varied as the experience in which they are rooted. The following displays the core or central insight.

1. The universe displays a staggering amount of intelligibility, both within the things we observe and in the way these things relate to others outside themselves. That is to say: the way they exist and coexist display an intricately beautiful order and regularity that can fill even the most casual observer with wonder. It is the norm in nature for many different beings to work together to produce the same valuable end—for example, the organs in the body work for our life and health. (See also argument 8.)
2. Either this intelligible order is the product of chance or of intelligent design.
3. Not chance.
4. Therefore the universe is the product of intelligent design.
5. Design comes only from a mind, a designer.
6. Therefore the universe is the product of an intelligent Designer. ...

6. The Kalam Argument

The Arabic word kalam literally means "speech," but came to denote a certain type of philosophical theology—a type containing demonstrations that the world could not be infinitely old and must therefore have been created by God. This sort of demonstration has had a long and wide appeal among both Christians and Muslims. Its form is simple and straightforward.

1. Whatever begins to exist has a cause for its coming into being.
2. The universe began to exist.
3. Therefore, the universe has a cause for its coming into being. ...

7. The Argument from Contingency

The basic form of this argument is simple.

1.  If something exists, there must exist what it takes for that thing to exist.
2. The universe—the collection of beings in space and time—exists.
3. Therefore, there must exist what it takes for the universe to exist.
4. What it takes for the universe to exist cannot exist within the universe or be bounded by space and time.
5. Therefore, what it takes for the universe to exist must transcend both space and time.

 8. The Argument from the World as an Interacting Whole

[In] Three Conclusions

1. Since the parts make sense only within the whole, and neither the whole nor the parts can explain their own existence, then such a system as our world requires a unifying efficient cause to posit it in existence as a unified whole.
2. Any such cause must be an intelligent cause, one that brings the system into being according to a unifying idea. For the unity of the whole—and of each one of the overarching, cosmic-wide, physical laws uniting elements under themselves—is what determines and correlates the parts. Hence it must be somehow actually present as an effective organizing factor. But the unity, the wholeness, of the whole transcends any one part, and therefore cannot be contained in any one part. To be actually present all at once as a whole this unity can only be the unity of an organizing unifying idea. For only an idea can hold together many different elements at once without destroying or fusing their distinctness. That is almost the definition of an idea. Since the actual parts are spread out over space and time, the only way they can be together at once as an intelligible unity is within an idea. Hence the system of the world as a whole must live first within the unity of an idea. ...
3. Such an ordering Mind must be independent of the system itself, that is, transcendent; not dependent on the system for its own existence and operation. For if it were dependent on—or part of—the system, it would have to presuppose the latter as already existing in order to operate, and would thus have to both precede and follow itself. But this is absurd. Hence it must exist and be able to operate prior to and independent of the system.

Thus our material universe necessarily requires, as the sufficient reason for its actual existence as an operating whole, a Transcendent Creative Mind.

9. The Argument from Miracles

1. A miracle is an event whose only adequate explanation is the extraordinary and direct intervention of God.
2. There are numerous well-attested miracles.
3. Therefore, there are numerous events whose only adequate explanation is the extraordinary and direct intervention of God.
4. Therefore God exists. ...

10. The Argument from Consciousness

1. We experience the universe as intelligible. This intelligibility means that the universe is graspable by intelligence.
2. Either this intelligible universe and the finite minds so well suited to grasp it are the products of intelligence, or both intelligibility and intelligence are the products of blind chance.
3. Not blind chance.
4. Therefore this intelligible universe and the finite minds so well suited to grasp it are the products of intelligence.

11. The Argument from Truth

This argument is closely related to the argument from consciousness. It comes mainly from Augustine.

1. Our limited minds can discover eternal truths about being.
2. Truth properly resides in a mind.
3. But the human mind is not eternal.
4. Therefore there must exist an eternal mind in which these truths reside.

12. The Argument from the Origin of the Idea of God

This argument, made famous by Rene Descartes, has a kinship to the ontological argument. It starts from the idea of God. But it does not claim that real being is part of the content of that idea, as the ontological argument does. Rather it seeks to show that only God himself could have caused this idea to arise in our minds.

It would be impossible for us to reproduce the whole context Descartes gives for this proof (see his third Meditation), and fruitless to follow his scholastic vocabulary. We give below the briefest summary and discussion.

1. We have ideas of many things.
2. These ideas must arise either from ourselves or from things outside us.
3. One of the ideas we have is the idea of God—an infinite, all-perfect being.
4. This idea could not have been caused by ourselves, because we know ourselves to be limited and imperfect, and no effect can be greater than its cause.
5. Therefore, the idea must have been caused by something outside us which has nothing less than the qualities contained in the idea of God.
6. But only God himself has those qualities.
7. Therefore God himself must be the cause of the idea we have of him.
8. Therefore God exists. ...

13. The Ontological Argument

The ontological argument was devised by Anselm of Canterbury (1033-1109).

1. It is greater for a thing to exist in the mind and in reality than in the mind alone.
2. "God" means "that than which a greater cannot be thought."
3. Suppose that God exists in the mind but not in reality.
4. Then a greater than God could be thought (namely, a being that has all the qualities our thought of God has plus real existence).
5. But this is impossible, for God is "that than which a greater cannot be thought."
6. Therefore God exists in the mind and in reality.

14. The Moral Argument

1. Real moral obligation is a fact. We are really, truly, objectively obligated to do good and avoid evil.
2. Either the atheistic view of reality is correct or the "religious" one.
3. But the atheistic one is incompatible with there being moral obligation.
4. Therefore the "religious" view of reality is correct. ...

15. The Argument from Conscience

Thus God, or something like God, is the only adequate source and ground for the absolute moral obligation we all feel to obey our conscience. Conscience is thus explainable only as the voice of God in the soul. The Ten Commandments are ten divine footprints in our psychic sand. ...

16. The Argument from Desire

1. Every natural, innate desire in us corresponds to some real object that can satisfy that desire.
2. But there exists in us a desire which nothing in time, nothing on earth, no creature can satisfy.
3. Therefore there must exist something more than time, earth and creatures, which can satisfy this desire.
4. This something is what people call "God" and "life with God forever."

C. S. Lewis, who uses this argument in a number of places, summarizes it succinctly:

Creatures are not born with desires unless satisfaction for these desires exists. A baby feels hunger; well, there is such a thing as food. A dolphin wants to swim; well, there is such a thing as water. Men feel sexual desire; well, there is such a thing as sex. If I find in myself a desire which no experience in this world can satisfy, the most probable explanation is that I was made for another world. (Mere Christianity, Bk. III, chap. 10, "Hope") ...

17. The Argument from Aesthetic Experience

There is the music of Johann Sebastian Bach.
Therefore there must be a God.

You either see this one or you don't.

18. The Argument from Religious Experience

It is difficult to state this argument deductively. But it might fairly be put as follows.

1. Many people of different eras and of widely different cultures claim to have had an experience of the "divine."
2. It is inconceivable that so many people could have been so utterly wrong about the nature and content of their own experience.
3. Therefore, there exists a "divine" reality which many people of different eras and of widely different cultures have experienced.

19. The Common Consent Argument

This proof is in some ways like the argument from religious experience and in other ways like the argument from desire. It argues that:

1. Belief in God—that Being to whom reverence and worship are properly due—is common to almost all people of every era.
2. Either the vast majority of people have been wrong about this most profound element of their lives or they have not.
3. It is most plausible to believe that they have not.
4. Therefore it is most plausible to believe that God exists. ...

20. Pascal's Wager

As originally proposed by Pascal, the Wager assumes that logical reasoning by itself cannot decide for or against the existence of God; there seem to be good reasons on both sides. Now since reason cannot decide for sure, and since the question is of such importance that we must decide somehow, then we must "wager" if we cannot prove. And so we are asked: Where are you going to place your bet?

If you place it with God, you lose nothing, even if it turns out that God does not exist. But if you place it against God, and you are wrong and God does exist, you lose everything: God, eternity, heaven, infinite gain. "Let us assess the two cases: if you win, you win everything, if you lose, you lose nothing." ...