Why Do You Believe In God, When We Have the Principle of Sufficient Reason?
What happens when someone tries to out-presuppose the presuppositionalist?
That’s exactly what happened in a recent debate I had with an agnostic who grounded his worldview not in God, but in the Principle of Sufficient Reason (PSR). You know the PSR: the idea that everything that exists has an explanation for its existence, either in the necessity of its own nature or in something external to it.
He claimed that by appealing to PSR and an argument form he called “torsion,” he could ground the laws of logic, the self, the external world—basically the whole set of transcendental preconditions for knowledge. He thought that, by doing so, he could do an end-run around the Christian God and still have a coherent worldview.
But here’s the thing: he couldn’t.
And this article is going to show you why.
The Argument I Presented
Let me lay out what I argued in that discussion. I made the case that the triune God of the Bible is the necessary precondition for all knowledge. We know this through the impossibility of the contrary.
In other words, the only way to make sense of the laws of logic, moral absolutes, and scientific inquiry is to start with the God of Scripture. He is the metaphysical foundation that grounds all these things. Without Him, you don't just lose Christianity. You lose intelligibility itself.
This isn’t a hypothetical syllogism. This isn’t just saying, “If God, then logic; we have logic; therefore, God.” That would be a direct argument. I was presenting an indirect argument. A transcendental argument. The impossibility of the contrary.
And it goes like this: unless the Christian God exists, you can’t make sense of anything. So when someone denies that God exists, yet continues using logic, moral absolutes, and the scientific method, they’re actually borrowing from my worldview. They are tacitly assuming the very God they claim not to believe in.
The Agnostic's Attempt at a Counter
Now, here’s where it got interesting. My interlocutor said he agreed that there are transcendental preconditions. He even agreed that logic, the self, and the external world were real.
But then he introduced his substitute for God: the Principle of Sufficient Reason. And not just the PSR, but a move he called “torsion,” which was supposed to justify those preconditions through a transcendental route. He claimed that if you negate any of those preconditions, you end up in absurdity. So therefore, they must be true.
Sound familiar?
Yeah. That’s our argument.
The problem is, without God, you’re left asserting transcendental principles as brute facts. And when I pressed him to explain what grounds the PSR—what gives it its ontological foundation—his answer was essentially, "Everywhere you go, there it is."
That’s not an argument. That’s just restating your premise.
The Crux of the Debate: Prime Reality
So I asked him: what is prime reality? What is the most fundamentally real thing in your worldview?
He said: the Principle of Sufficient Reason.
Now let’s pause here. A principle. A proposition. A conceptual entity.
He’s saying that the foundational reality of everything—what everything else depends on—is a concept.
But concepts are by nature mental. They exist in minds. They don’t float freely in some Platonic ether. They don’t create anything. They can’t act. They can’t reason. They can’t reveal.
So my next question was obvious: Whose mind does the PSR exist in?
He had no answer.
Because in his worldview, there is no personal, necessary mind to house it. The PSR just… is. But he rejected the idea of God, so he had to say that a proposition exists necessarily and metaphysically as prime reality.
That’s not a worldview. That’s a floating abstraction.
Why Christianity Alone Grounds Logic
Now contrast that with Christianity.
In the Christian worldview, the laws of logic, the principle of sufficient reason, and other transcendental truths are grounded in the nature of the triune God. God is:
Immaterial
Eternal
Unchanging
Omniscient
Truthful
Triune
Because God exists necessarily, the laws of logic are necessarily grounded in His mind. They are an expression of His nature. That’s why they are invariant, immaterial, and universally applicable.
This is what Van Til meant when he said that antitheism presupposes theism. To even argue against God, you must first sit in His lap, as it were. You must borrow the very tools of logic and reason that only He can provide.
The Demand to Refute Every Worldview
Now, my opponent kept demanding, "How do you know Christianity is the only worldview that works? Have you refuted every other worldview?"
And here's where the disjunctive syllogism comes in. Christianity, by its own claims, is exclusivist. Jesus said, "I am the way, and the truth, and the life. No one comes to the Father except through me" (John 14:6).
If Christianity is true, all contrary worldviews are necessarily false. That’s not a cop-out. That’s how exclusive claims work.
We don’t need to refute every worldview piecemeal. We can refute them in principle, by showing that only Christianity can account for the preconditions of intelligibility. If one worldview provides the necessary grounding, then all others that contradict it are false by definition.
That’s not dogmatism. That’s logic.
The Fatal Flaw in the PSR-Only Worldview
Here’s what it all boiled down to: my opponent wanted to make a conceptual proposition the foundation of all reality. But he had no mind to house that concept, no personality to reveal truth, and no creator to justify it.
At one point, I asked him if the PSR created itself. He didn’t answer. I asked if it was made of matter. He didn’t know. I asked if it existed in a mind. He deflected.
This is the problem with trying to out-presuppose the presuppositionalist. Without the triune God of Scripture, you're just trying to ground truth in thin air.
Meanwhile, the Christian worldview gives you exactly what you need:
A necessary mind
A revelatory God
A consistent nature
A personal Lord who can communicate with us
God is not just a necessary being. He is the necessary precondition for all rational thought, discourse, and knowledge.
Conclusion: The Impossibility of the Contrary
So no, the PSR cannot replace God.
Not even if you call it "torsion."
Concepts without a mind are nothing. Propositions don’t create. Abstract principles don’t explain reality. Only the personal, triune God of Scripture gives us a coherent foundation for logic, science, and morality.
To deny that is to undercut the very tools you're using to argue.
And that's the beauty of presuppositional apologetics: it shows that without God, you can't prove anything. But with Him, you can account for everything.
Want to See the Full Debate?
Watch the entire discussion, "Understanding Through Debate: A Dive into Theism and Sufficient Reason" right here (it’s timestamped at the exact moment this debate begins.
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