Summary: This article proposes a novel definition of truth: the totality of reason—objective explanations for reality that are universally understandable and reduce doubt. Proving a statement's truth is nothing more than providing reasons for that statement.
This approach reveals truth and reason as co-dependent. By understanding how truth is grounded in reasons, we can clarify how the principle of sufficient reason is self-evident. Truth is not a mystical property beyond our access but the structured outcome of reasons—the justifications of our knowledge. While truth is beyond our direct access, we have such access to our justifications. Through these justifications, our minds can grasp truth.
1. On Truth (and why we should care)
What is truth? A big question. But a better one might be: Why do we care? Even if a philosopher blesses us with an airtight definition, does it matter? Isn’t this just semantics?
People apparently seem to know what truth is. It’s what’s objective, or what corresponds to reality, or what is “mind-independent.” But these descriptions are devoid of content, too literal to be helpful.
Moreover, these common definitions suggest that truth is something over and above our subjective minds—as if our subjectivity were one thing, and truth, something entirely separate.
What is the relationship between our minds and truth? How do our minds relate to the objective, and how can we access it? Correspondence theory doesn’t say. And its somewhat more meaningful competitors (coherence theory, pragmatism, and deflationism) have earned their own share of criticism.
You would expect philosophers to have come to some satisfying concept of “Truth.” However, for hundreds of years, philosophers have only discovered faults with proposed definitions of “Truth,” failing to reach a consensus on any of them. This is part of why some feel defeated in the goal of a meaningful concept of “Truth,” and they retreat to common intuition.
This skepticism toward philosophy is understandable. However, we shouldn’t be cynical about what we’ll find when we craft better definitions.
It’s by understanding the nature of belief, as I’ve defined it here, that we can understand Moore’s paradox. Decades of literature on this supposed paradox can be laid to rest by simply defining our terms.
This article will attempt to provide a coherent and meaningful concept of truth that unlocks further insight into philosophy, specifically the Principle of Sufficient Reason (PSR). Once we affirm the PSR, we can explore the furthest depths of philosophy.
Before we can build a system, we need to lay the foundation. We’ll start, as philosophy always must, by precisely defining our terms.
2. Defining Truth (Truth as Reasons)
Truth is the totality of reasons. Nothing more, nothing less. And by “reasons,” I mean objective explanations that reduce doubt and are universally comprehensible (as I’ve described here).
Each domain has its own type of “objective explanations” for the truths it discovers:
Mathematics: Logical relationships and deductive proof.
Science: Observation, experimentation, and predictive power.
History: Evidence from artifacts, documents, and records.
Philosophy: Conceptual coherence and intuitive plausibility.
Any worthy academic field that lays claim to any “truth” (economics, linguistics, psychology, etc.) offers truths grounded in its own kinds of reasons.
Truth depends on reasons, regardless of the type of truth. Truth exists because there is a reason for it. We can even frame “truth” as the set of all propositions that follow from the set of all reasons.
We can think of truth as a puzzle. All of these reasons—provided that they are logically coherent and sensible—can fit together to present a clear picture. The more pieces we put together, the clearer the image becomes.
Once we have all the reasons structured like a neat puzzle, truth is revealed. Truth emerges from the puzzle. Truth is somehow over and above the puzzle, yet nothing more than the actual puzzle.
Just as a building is nothing more than its materials, truth is nothing more than the reasons that support it.
These reasons, in turn, must also be true and supported by further reasons. This leads us down a chain of reasoning until we reach foundational, self-evident truths.
Some truths are self-justifying, like “1 = 1” or “I feel hungry.” These are self-evident, foundational truths that serve their own reasons. In philosophical terms, this is foundationalism. It is these foundational reasons that ground the truths that rest on them.
A reason is valid only if it explains a truth. A truth is valid only if it has reasons supporting it.
This interdependence shows that truth and reason cannot be separated. To prove a proposition is true, one must offer sufficient reasons. To disprove it, one must show that the claim lacks reasons.
In summary, truth and reasons are co-determinate—two sides of the same equation.
While this may sound like a theory of justification, that’s exactly the point: All truth is justified.
Although we may not have direct access to truth, we have access to reasons —the justifications for truth. For us to know something, we need to know the reasons for that thing (what I call “connectors” in this linked definition of knowledge). And these reasons must actually relate to truth.
Truth being grounded in reasons is exactly what the PSR asserts. By defining Truth, we can hopefully see more clearly why the PSR is self-evident.
3. Truth and the PSR
The PSR affirms that all truths must have a reason. As applied here, that means that reasons must support every truth. Everything comes with an explanation. Otherwise, what use is there in trying to understand the world? If there are no underlying reasons, it would be useless to try to make sense of anything. Yet in studying the world, we search for explanations that we know must exist.
Epistemology is the study of how we discover and come to know reasons. Specialized fields in the sciences are dedicated to certain domains of “reasons” and “truths.”
As I’ve shown when defining “knowledge” (another useful definition that isn’t just semantics), we can’t claim to know something if the evidence we have doesn’t actually relate to the fact in question.
Charles Sanders Peirce’s epistemic approach to truth describes it as the conclusion we arrive at through evidence-based inquiry.
More precisely, it is “concordance of an abstract statement with the ideal limit towards which endless investigation would tend to bring scientific belief.”
As Peirce affirmed, evidence and truth are not separate. Just as truth follows from evidence, it is evidence that leads us to truth.
If our theory of truth is sound (that truth is just what is justified by reason), then the PSR follows naturally. Just by defining truth, we can see that the PSR is, again, self-evident.
In the next installment, I’ll discuss how this theory of truth relates to its other theories (correspondence theory, coherence theory, pragmatism, and deflationism) and how it takes the best aspects of each while discarding their limitations.
But in the meantime, hit me with your hardest criticism. Let’s give this conception of truth a serious stress test.
4. Conclusion
While truth is beyond our direct access, truth isn’t some mystical property floating beyond our grasp. It is nothing more and nothing less than the sum of all reasons.
Rather, “Truth” is grounded in objective and justifiable explanations. We may not have access to the truth directly, but we have access to reasons. To have knowledge of the world is nothing more than having a correctly structured set of reasons.
When we understand truth this way, the PSR doesn’t just make sense—it becomes inevitable. This isn’t merely semantics. The definition of “Truth” is part of the foundation for taking on the hardest questions in philosophy.
Also, evolutionary debunking arguments could explain why reasonable disagreement about morality is so intractable:
https://link.springer.com/article/10.1007/s10677-022-10275-y
The PSR is to contingently true brute facts what the 5th axiom of Euclidean geometry is to Non-Euclidean geometry. Non-Euclidean geometry is internally consistent despite the fact that Non-Euclidean geometry contradicts the 5th axiom of Euclidean geometry. Similarly, the statement “contingently true brute facts exist” is internally consistent despite the fact that such statement contradicts the PSR. This doesn’t imply that the PSR is false. However, it does imply that if the PSR is true, then the statement “contingently true brute facts exist” would be an internally consistent falsehood.