The Inadequacies of Rational, A Posteriori Proofs for the Existence of God
Philosophers throughout history—like Aristotle, Aquinas, and Kant—have tried to prove God’s existence through logic, observation, and reason. These are called a posteriori proofs—arguments that begin with what we see and experience in the world, and reason upward to a divine cause.
While these attempts may show that belief in God is reasonable, they fall short of bringing anyone to the true and living God revealed in Scripture. Let’s see why.
1. THEOLOGICAL INADEQUACIES
a. Lack of a True Foundation for Truth
Human reasoning, by itself, cannot be the foundation for truth. According to Scripture, truth is not something we discover by sifting through data—it is something God declares.
“Sanctify them by the truth; your word is truth.” — John 17:17 (NIV)
Truth is not neutral; it flows from the nature of God Himself. Even when unbelievers acknowledge some truths (like moral laws, beauty, or logic), they do so while standing on ground borrowed from a theistic worldview.
Imagine a child sitting on her father’s lap, slapping him and shouting, “You don’t exist!” The very act of defiance depends on the father’s presence. Similarly, when skeptics use logic or morality to argue against God, they are using tools that only make sense because God exists.
So, without God as the foundation, human reason becomes like a house built in midair—impressive perhaps, but without any ground to stand on.
b. Dependence on Human Objectivity
Rational proofs assume that humans can reason objectively—from ignorance to knowledge of God. But Scripture paints a different picture of the human condition.
Romans 8:7— “The mind governed by the flesh is hostile to God; it does not submit to God’s law, nor can it do so.”
Ephesians 4:18— “They are darkened in their understanding and separated from the life of God…”
Because of sin, our reasoning faculties are corrupted. We are not neutral observers of truth—we are rebels who suppress it.
Think of a judge who insists he can deliver a fair verdict while his own son is on trial. His judgment is inevitably biased. In the same way, fallen human reason cannot approach God with neutrality; our hearts have a built-in bias against Him.
Unaided reason might recognize a Creator but will twist that recognition into something more comfortable, something that doesn’t require repentance.
c. Inability to Identify the True God
Even if reason convinces someone that there is a “higher power,” it provides no way to know who that being is. Philosophy may take you to a “first cause,” but only revelation takes you to the cross.
History is filled with examples of people discovering some form of divine existence yet arriving at false gods:
- Deism: God made the world but left it running on its own.
- Atheism: There is no God.
- Skepticism: We can’t be sure God exists.
- Agnosticism: It’s impossible to know.
- Pantheism: Everything is God.
- Polytheism: Many gods exist.
- Animism & Fetishism: Spirits or objects have divine power.
Trying to find the true God by reason alone is like trying to identify the author of a book just by studying the paper and ink. You might learn something about the materials, but never the mind and heart of the one who wrote it. Only when the author signs the book or reveals himself can you know who he truly is.
Thus, reason without revelation leads to endless distortions of deity—each reflecting human imagination more than divine truth.
2. LOGICAL INADEQUACIES
a. Infinite Regress
Many philosophical arguments—like the cosmological argument—reason that everything that exists has a cause. But if every cause needs another cause, we end up in an infinite loop. Unless there is a first, uncaused cause, the reasoning never reaches a conclusion.
It’s like a row of dominoes stretching back infinitely. You can watch them fall forever, but unless there’s a first hand that pushed the first domino, nothing ever gets started. Human reason alone cannot reach that first, necessary Being—it only keeps asking “What caused that?” forever.
b. No Guarantee of One True God
Even if logic proves that some higher being must exist, it doesn’t mean that being is the God of Scripture—personal, triune, and sovereign. Philosophical reasoning could just as easily point to a group of powerful beings, or an impersonal force.
A detective might conclude that “someone” committed a crime based on the evidence—but that doesn’t tell him who it was. He needs the criminal’s confession or witness testimony. In the same way, reason might say “a God exists,” but only revelation tells us who He is.
c. Only a Probability
At best, rational proofs can argue that God probably exists. But Scripture speaks with divine certainty:
Psalm 14:1 — “The fool says in his heart, ‘There is no God.’”
You can stand at the edge of the ocean and reason that the horizon probably continues beyond your sight. But only the sailor who has crossed it can tell you what lies beyond. God’s revelation in Scripture is that sailor’s testimony—it gives certainty, not probability.
d. A Fallacy of Scale
Finally, rational proofs often make a faulty leap—from the finite to the infinite. Observing order and beauty in the universe might point to a Designer, but that doesn’t logically prove infinity, omniscience, or holiness.
A child might see a paper airplane and reason, “Someone must have made it.” But that doesn’t mean he can conclude that Boeing exists. Similarly, looking at the created world can tell us there is a Maker, but not who that Maker is in His fullness.
Summary: Revelation, Not Reason, Reveals God
At the end of the day, rational and empirical arguments can hint at a divine reality—but they can never bring us face to face with the personal, triune God of the Bible.
True knowledge of God comes only through revelation—God making Himself known through His Word and through His Son, Jesus Christ.
Matthew 11:27— “No one knows the Father except the Son and those to whom the Son chooses to reveal Him.”
Faith, then, does not rest on human logic but on God’s self-disclosure.
If the heavens declare God’s glory (Psalm 19:1), that’s like seeing a beautifully wrapped letter written across the sky. But only when you open Scripture do you read the words inside. The stars can tell you that He is there—but the Bible tells you who He is.
Stand Firm! 