Fr. John J. Pasquini
C.S. Lewis’ argument from desire is found succinctly in Mere Christianity: “Creatures are not born with desires unless satisfaction for these desires exist. A baby feels hunger: well, there is such a thing as food. A duckling 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 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, San Francisco: Harper Collins, 2015), Book 3, Chapter 10).
The more formal explanation of Lewis’ argument goes as follows: 1) Every innate desire in us corresponds to a real thing that can satisfy that desire. 2) There exists in us one innate desire which nothing on earth can satisfy. 3) There must, therefore, exist something which is beyond this earth that can satisfy this desire. 4) This something is what we call God.
When discussing desires, Lewis makes a distinction between innate desires and externally conditioned desires. Innate desires come from our nature; they are inborn and universal—that is, they are common to all healthy people. Externally conditioned desires are acquired through the external influences of the culture we live in. Unlike innate desires, which are found in all healthy people, externally conditioned desires vary from person to person.
Externally conditioned desires do not necessarily correspond to things that exist. I desire that the United States be protected by the superheroes Batman and Superman. Batman and Superman do not exist. Innate desires, however, always corresponds to things that exists. As the philosopher Peter Kreeft has explained, echoing the consensus of philosophers, when it comes to innate desires “no one has ever found one case of an innate desire for a nonexistent object.” (Handbook of Christian Apologetics: Hundreds of Answers to Crucial Questions, Downers Grove, IVP Academic, 1994, 49f). I desire food, food exists. I desire drink, drink exists. I desire knowledge, knowledge exists. Our innate desires correspond to real things.
Human experience teaches us that there exists in us an innate desire which nothing on earth can satisfy. Within every person there is the question: “Is this all there is?” Or in the words of the atheist emperor Severus, “I have had everything, and everything is nothing.” There is an emptiness that seeks to be filled, and nothing in this world can fill or satisfy it. Since every innate desire has a corresponding reality, according to the consensus of philosophers, there must be something beyond this world that fulfills this innate desire that nothing in this world can satisfy. The desire for God fulfills that innate desire that nothing in this world can satisfy. As the great Augustine explained, echoing Psalm 62 and the hearts of all those who have sought and have found, “Only in God is my soul at rest.”
One may argue that evolution has inbred this innate desire into human beings, and that this innate desire for God’s existence happens to be the only inbred, innate desire that does not correspond to a reality or real thing. Is this possible, maybe; but this would make the innate desire for God the only innate desire in the world that has no corresponding reality! Thus for C.S. Lewis the likelihood of God’s existence based on innate desires favors the existence of God.