Third Proof of God: The Argument from Contingency

Thomas Aquinas’s third argument for the existence of God is called the Argument from Contingency. This proof answers the question, “Why does anything exist at all?” Let’s explore this idea in simple language with relatable analogies and examples that even a high schooler can understand.

The Big Idea: Things Depend on Other Things

Think about the world around you. Almost everything you see exists because of something else:

• A house exists because builders constructed it using materials like wood, steel, and concrete.
• A tree grows because it has soil, water, sunlight, and air.
• You exist because your parents gave you life, and you depend on food, air, and water to stay alive.

In philosophy, we call these “contingent” things. A contingent thing is something that depends on something else for its existence.

What if Everything is Contingent?

Here’s where things get interesting. If everything in the universe is contingent—that is, dependent on something else—then we have to ask, “What started it all?” If every thing depends on another thing to exist, we can’t have an infinite chain of dependencies. At some point, there must be something that doesn’t depend on anything else. This is what Aquinas called a “necessary being.”

An Analogy: The Lamp and Electricity

Imagine a lamp in your room. The lamp depends on electricity to produce light. But where does the electricity come from? Maybe it comes from a power plant. And where does the power plant get its energy? Perhaps it’s from burning fuel or capturing sunlight. Eventually, you have to ask, “What is the ultimate source of energy?”

If you keep going back in the chain of dependencies, there must be a source that doesn’t depend on anything else. This ultimate source is like God—a necessary being that doesn’t depend on anything but makes everything else possible.

A Real-World Example: The Universe Itself

Scientists agree that the universe had a beginning, often called the Big Bang. But why did the Big Bang happen? What caused it? While science explores the “how,” Aquinas’s argument points us to the “why.” If the universe is contingent, it needs something outside itself to explain why it exists at all. Aquinas argues that this “necessary being” is God.

An Analogy: The Stack of Books

Picture a stack of books on a table. Each book in the stack is being held up by the book beneath it. But if there’s no table to hold the bottom book, the entire stack would fall. Similarly, if there’s no necessary being to support the existence of contingent things, nothing would exist at all. God, Aquinas says, is like that table—the foundation that supports everything.

Conclusion

The Argument from Contingency asks us to think about why anything exists instead of nothing. Everything we see depends on something else, but the chain of dependencies can’t go back forever. There must be a necessary being—something that exists by its very nature and doesn’t depend on anything else. For Aquinas, this is God—the ultimate source of existence.

By reflecting on examples like lamps, books, and the universe itself, we can begin to see why this argument has inspired thinkers for centuries. It’s a logical way to think about the existence of everything around us.

References

• Aquinas, Thomas. Summa Theologica. Translated by Fathers of the English Dominican Province. Benziger Bros., 1947. Available online at: New Advent.
• Feser, Edward. Five Proofs of the Existence of God. Ignatius Press, 2017.
• Craig, William Lane. Reasonable Faith: Christian Truth and Apologetics. Crossway, 2008.
• Hawking, Stephen, and Mlodinow, Leonard. The Grand Design. Bantam Books, 2010.