4. Tracing Truth: Certainty And Its Collapse

The Search For Certainty

How did we get here in the first place with truth? How did it get so pervasive, and why is it broken even though everybody pretends it's not?

The next chapters trace the making and unraveling of truth. Not as a neutral history, but as a story of recurring collapses. For centuries, truth was seen as something stable, a foundation on which knowledge could stand. But as thinkers pushed deeper, cracks formed. Each attempt to justify truth only made the ground beneath it less secure.

The philosophers in this chapter did not seek to destroy truth. They were trying to clarify and save it. Yet, one by one, they dismantled its foundation, often without intending to. What began as a project of securing certainty ended with its collapse. And once certainty was gone, the very idea of truth was on the line.

This collapse did not happen all at once. It unfolded in stages. And to understand how we arrived at the need for Conviction Formation Theory, we must follow the path of those who first tried to hold truth together.

René Descartes stands out for a claim as bold as the Montgolfier brothers' dream of defying gravity, something once thought reserved for birds and angels.

He claimed that absolute certainty was possible. Not by avoiding doubt, but by using it as a tool.

He turned away from external sources of knowledge and looked inward, convinced that truth must be built on something undeniable, a foundation that could not be shaken.

Before Descartes, truth was often distinguished from non-truth through appeal to authority, tradition, or divine order, whether in Aristotelian metaphysics, Scholastic reasoning, or religious revelation. There was a mainstream background of truth that was not doubted. After Descartes, truth had to be reconstructed from first principles, from the ground up, proved foundations.

His revolution forced all later thinkers to take a stand on this problem.

Descartes: The Search For A Certain Foundation

Philosophy did not begin with René Descartes, but modern philosophy did.

Thinkers before him had debated truth, knowledge, and certainty for centuries, but Descartes did something different: he changed the very method of philosophy itself. He set it on a new trajectory, one that all later thinkers would either follow or resist.

To understand what he did, we do not need to retrace every step that led to him. The history is rich, and much can be learned from it. But we need only to see what he saw: the fragile ground on which truth was standing, and the foundation he believed he could build in its place.

When Descartes set out to rebuild philosophy, the world was still shaped by the convictions of Scholasticism.

Scholasticism was an intricate system in which truth was anchored in authority: the authority of the Bible, the Church Fathers, and Aristotle, with his logic and categories. Knowledge was seen as hierarchical, passed down through authoritative texts, and aligned with a divinely ordered universe. The senses were trusted in everyday life, but ultimate certainty rested in the rational structure of the cosmos, overseen by God.

Yet Descartes stood at the threshold of modernity. Copernicus had displaced the Earth from the center of the cosmos. Galileo had defied church doctrine with his telescope. Skepticism was beginning to seep into intellectual life.

Descartes thought this patchwork of convictions demanded a response. It needed a new foundation. Instead of treating uncertainty as a problem to be minimized, he made it his method. He would systematically doubt everything that could be doubted, stripping away assumptions until only what was truly certain remained. To avoid being misled by reason itself, he would consider only ideas that were clear and distinct. This, he believed, would reveal knowledge beyond question and allow him to distinguish truth from non-truth.

Once these indubitable foundations were set, logic alone would suffice to build the cathedral of certainty upon them.

A prolific mathematician himself, Descartes found his model in the mathematics of his time. Unlike the shifting debates of philosophy or the uncertainties of the empirical sciences, mathematics proceeded step by step from simple, self-evident truths to complex conclusions. He believed that all knowledge could be structured in this way.

In his Discourse on Method, he wrote:

"I was particularly fond of mathematics, because of the certainty and the self-evidence of its reasoning; but I did not yet understand its true use; and, thinking that it served only the mechanical arts, I was astonished that given that its foundations were so firm and solid, nothing more elevated had been built upon them[.]"

["Je me plaisais surtout aux mathématiques, à cause de la certitude et de l'évidence de leurs raisons: mais je ne remarquais point encore leur vrai usage; et, pensant qu'elles ne servaient qu'aux arts mécaniques, je m'étonnais de ce que leurs fondements étant si fermes et si solides, on n'avait rien bâti dessus de plus relevé[.]"]

To bring this cathedral to life, Descartes turned inward. In a radical act of doubt, he dismantled every conviction he could. He imagined that the senses might deceive, that dreams might blur into waking life, that everything might be an illusion produced by a powerful demon. What, then, could withstand such skepticism?

Only this: that while doubting, he was still thinking. And if he was thinking, he must exist. Cogito, ergo sum. I think, therefore I am.

This was his first clear and distinct certainty, the first foothold on which truth could be rebuilt. Nothing was yet secured except this: that he was thinking, that he existed as a thinking being.

Within his thoughts, Descartes then claimed to find a clear and distinct idea of God. But, he argued, such an idea could not have originated from him. He was finite and imperfect, yet the idea of God was infinite and perfect. If the idea were his own creation, it would be limited like him. Only a perfect being could be the source of the idea of perfection itself. Therefore, God must exist.

And since God is good, which is part of the very idea of God as a perfect being, God does not deceive us. We may err when we judge matters we do not yet understand clearly, but we have been given intellect by a good God. If we attend carefully to clear and distinct ideas, truth is within reach.

In this way, Descartes continued an older conviction, that divine order underlies reality. But the role of God had shifted. God was no longer the starting point of knowledge. He had become its guarantor. Descartes was certain that God exists for the reasons he had given, and because God is good, God could not be a deceiver.

His system attempted to give a rational underpinning to a familiar idea of truth: that what we say and think, when it is true, corresponds to something in the world. God, in Descartes' system, guarantees exactly this correspondence. He believed he had opened the door to secure knowledge, grounding the certainty of mathematics in something even more certain.

Viewed through the lens of conviction formation, Descartes seems to have believed that once his ideas were clearly explained and properly understood, they would naturally become convictions for anyone who grasped them. This assumption was tied to his belief in innate ideas, or one might say innate convictions. Certain fundamental truths, such as the existence of God or the nature of the self, were already embedded in human reason. If reason operated universally and without distortion, then clear and distinct truths would compel conviction in all rational minds.

If Descartes had lived to see the foundational crisis of mathematics in the late nineteenth and early twentieth centuries, would he still have trusted clarity and distinctness as the ultimate guides to truth? Or would he have turned his doubt back on the very method that had anchored his philosophy? Given the brilliance and seriousness of his mind, it is hard to imagine that he would not have reconsidered.

He cannot do so anymore. But we are still living in Descartes' wake.

His conviction that truth must be justified by reason alone remains one of the great shifts in intellectual history. He helped liberate the individual thinker from inherited truth, placing the responsibility for knowledge not in tradition, but in personal reason and reflection. Convictions that cannot be justified in this way come to seem suspect, or at least diminished.

Descartes built a cathedral. But soon, a man named John Locke would begin to question whether some of its building material was viable at all.

Conviction Shift: Descartes

Descartes shifted the justification of truth from external authority to individual reason. He sought certainty through methodical doubt, beginning with "I think, therefore I am," and attempted to reconstruct knowledge step by step. The existence of God, understood as an innate idea, was meant to guarantee that clear and distinct ideas correspond to reality.

But this reliance on innate ideas opened a new line of doubt: What if clarity and distinctness are not enough? And what if the foundation itself turns out to be less secure than it appears?

Locke: Knowledge Through Experience, Not Innate Ideas

When Descartes sought certainty, he looked inward, turning to the clarity of reason. He believed truth had to be grasped through pure thought, secured by self-evident, indubitable principles alone. John Locke took a different path. Instead of starting with reason, he started with the world.

Born into an England shaped by civil war, religious upheaval, and scientific discovery, Locke lived in a time when authority was being questioned in every domain. Political power was no longer assumed to be divinely ordained, but challenged and debated. The disintegration of the old order was on full display. The foundations of knowledge were cracking even more visibly than in Descartes' time.

Like Descartes, Locke accepted the certainty of mathematical truths and the idea that certainty mattered for how truth itself was conceived.

Locke, however, claimed that the mind begins as a blank slate, a tabula rasa. We are not born with innate ideas already inscribed within us. All knowledge comes from experience.

This was a direct rejection of René Descartes. If ideas were truly innate, Locke reasoned, they would appear in everyone, regardless of culture, upbringing, or education. But they do not. The truths we take to be self-evident are, in fact, learned.

Put in modern terms: if the idea of God as the highest being were truly clear, distinct, and innate, how is it that neither Gautama Buddha nor any of his followers arrived at it through meditation?

For Locke, experience was the source of all knowledge. Experience unfolded through two faculties working together: sensation and reflection. Sensation provided direct contact with the world. Reflection allowed the mind to process, compare, and analyze what had been gathered. Knowledge took shape through their interaction. Nothing was present before experience. It emerged from it.

Where Descartes had sought certainty through innate ideas, Locke sought it through reflection as part of experience. Reflection does not precede experience. It begins with it and builds ideas stone by stone. It may become a cathedral for one mind, and a straw hut for another.

This is not innate knowledge. Innate knowledge, if it existed, would be present in the mind from birth. Locke denied that such knowledge exists. There are no ideas that appear fully formed without experience.

Instead, knowledge is acquired through reflection on ideas first supplied by sensation. Once we have encountered the color white through experience, we can reason about it independently. We do not need to inspect countless white objects to know that whatever is white is indeed white.

This is intuitive knowledge, and it is certain. It is true because the mind perceives the agreement or disagreement between ideas directly, without returning to the world for further confirmation.

A second form of certain knowledge is demonstrative knowledge. Here the mind does not grasp truth immediately, as with intuitive knowledge, but arrives at it through a sequence of clear and connected steps.

Knowledge of empirical objects, however, can never reach certainty. All we receive from objects are the sensations they produce in us. For Locke, probability is the highest standard attainable in this domain.

No indubitable idea proves that I exist as a thinking being. No innate idea proves that God exists. And if God's existence is uncertain, then God cannot serve as a guarantor that our perceptions match the world they purport to describe. For Locke, knowledge of external objects is excluded from certainty altogether.

This marks a decisive shift from Descartes. A whole domain of knowledge falls from certainty into probability.

The consequences reach into theories of truth. Correspondence between ideas can be judged directly by the mind, allowing certainty in logic and mathematics, much as Descartes had believed. But correspondence between ideas and external objects is never directly accessible. When truth concerns the external world, it is always approximate.

In An Essay Concerning Human Understanding, Locke distances himself explicitly from the Cartesian model of justification when he writes:

"For where is the man that has incontestable evidence of the truth of all that he holds, or of the falsehood of all he condemns; or can say that he has examined to the bottom all his own, or other men's opinions? The necessity of believing without knowledge, nay often upon very slight grounds, in this fleeting state of action and blindness we are in, should make us more busy and careful to inform ourselves than constrain others."

Believing without perfect knowledge, and without having examined all relevant grounds, is a condition of human life. It calls for careful inquiry rather than dogmatic certainty.

At the same time, truth remained Locke's guiding orientation. In a letter to his friend Anthony Collins, he writes: "To love truth for truth's sake is the principal part of human perfection in this world, and the seed-plot of all other virtues."

Unlike Descartes, who aimed to secure knowledge on an indubitable foundation, Locke accepted that most of what we believe is neither simply true nor simply false. It occupies a middle ground. What matters is how well it withstands experience and reflection.

Convictions were therefore provisional. Always open to revision, correction, and refinement. Locke recognized that people often hold beliefs with absolute confidence despite lacking absolute proof. Rather than treating this as a defect, he treated it as a basic feature of human cognition. Truth was not something to be possessed, but something to be pursued.

Locke's ideas reshaped not only philosophy, but also science, education, and politics. His arguments for natural rights and government by consent influenced the development of modern democratic thought. The framers of the U.S. Constitution drew heavily on his claim that legitimate political authority arises from the people rather than divine mandate. His emphasis on experience over innate reasoning laid the groundwork for empirical science, where knowledge is expected to be tested, revised, and updated. Education, in turn, shifted toward observation, reasoning, and exploration rather than passive transmission.

With Locke, the dream of an absolutely certain system gave way to something more grounded. Truth became less a destination than a path, especially when it concerned the objects of experience.

But even this more restrained vision would not remain intact. David Hume would push Locke's framework to its breaking point.

Conviction Shift: Locke

Locke rejected Descartes' appeal to innate ideas and argued that knowledge begins with experience, shaped through sensation and reflection. Certainty remained possible in logic and mathematics, where relations between ideas could be grasped directly. But knowledge of the external world was irreducibly probable, always subject to revision. Truth became a pursuit rather than a possession, and conviction a stance held under conditions of uncertainty.

Hume: The Collapse Of Certainty

If Locke had argued that convictions emerge from experience, David Hume pushed that idea to its breaking point. Locke's system rested on assumptions he had not fully examined.

Hume took Locke's empiricism seriously. Perhaps more seriously than Locke himself had dared. If all knowledge comes from experience, then we must examine what experience actually gives us. And, as Hume showed, it gives us far less than we tend to assume.

We naturally suppose that objects persist even when we are not observing them. The tree outside my window today is the same tree it was yesterday, an object that maintains identity through time and change.

Hume challenges this assumption in his A Treatise of Human Nature:

"But this conclusion beyond the impressions of our senses can be founded only on the connexion of cause and effect; nor can we otherwise have any security, that the object is not chang'd upon us, however much the new object may resemble that which was formerly present to the senses."

What Hume draws attention to is that common sense, and our ordinary talk about the world, rests on the assumption of a closed causal order. We assume that nothing changes without a cause.

Hume points out that we cannot even observe causation in individual cases. We see one event followed by another: a flame touches paper, the paper ignites. But the force that supposedly links them is never visible.

From this, Hume concludes that what we call causation is nothing more than constant conjunction, the repeated association of one kind of event with another. We never observe a necessary connection. We observe patterns, and from these patterns we form expectations. Through habit, the mind comes to expect one event after another, and we mistake this expectation for necessity. There is no logical requirement that the sun must rise tomorrow. There is only our belief that it will, grounded in past regularities.

This line of thought extends further. If causation lacks necessity, then everything that depends on it becomes unstable. Is the tree outside the same tree as yesterday? We believe so, but that belief rests on habit, not necessity. The self fares no better. We think of ourselves as unified and continuous beings, but when Hume examined his own mind, he found only a succession of fleeting perceptions, sensations, and thoughts. Never a stable, enduring self. The belief in personal identity is, once again, a conviction formed by habit rather than reflection. Even the belief that things exist independently of us is known only through the effects they have on our senses.

What remains secure are the demonstrative sciences: arithmetic and algebra. Hume acknowledges their certainty, but only in a limited sense. He writes in Book I of the Treatise:

"In all demonstrative sciences the rules are certain and infallible; but when we apply them, our fallible and uncertain faculties are very apt to depart from them, and fall into error."

To address this, he adds:

"We must, therefore, in every reasoning form a new judgment, as a check or controul on our first judgment or belief; and must enlarge our view to comprehend a kind of history of all the instances, wherein our understanding has deceiv'd us, compar'd with those, wherein its testimony was just and true."

And he concludes:

"Our reason must be consider'd as a kind of cause, of which truth is the natural effect; but such-a-one as by the irruption of other causes, and by the inconstancy of our mental powers, may frequently be prevented. By this means all knowledge degenerates into probability."

A familiar picture of truth is still present here. Reason aims at correspondence with reality. Truth is the natural effect of correct reasoning. But reason is an unreliable cause, constantly disrupted by other influences. Even the demonstrative sciences are vulnerable in their application. Certainty erodes from within.

At this point, certainty collapses entirely. Truth becomes a fragile and rare byproduct of reasoning. How far this is from where René Descartes began.

The Treatise of Human Nature strikes a distinctly heavy-hearted tone:

"When I turn my eye inward, I find nothing but doubt and ignorance. [...] For with what confidence can I venture upon such bold enterprizes, when beside those numberless infirmities peculiar to myself, I find so many which are common to human nature? Can I be sure, that in leaving all establish'd opinions I am following truth; and by what criterion shall I distinguish her, even if fortune shou'd at last guide me on her foot-steps? [... U]nderstanding, when it acts alone, and according to its most general principles, entirely subverts itself, and leaves not the lowest degree of evidence in any proposition, either in philosophy or common life."

Yet Hume was not a nihilist. The conclusion of Book I does not recommend abandoning belief. It recommends recognizing belief for what it is: a practical necessity rather than a logical achievement. Despite his skepticism, Hume still ate, trusted that food would nourish him, and expected the world to remain stable enough to play back-gammon. His philosophy was not a denial of reality, but an acknowledgment that human life cannot wait for absolute proof before it acts. Skepticism, he suggested, is not a way to live.

This may be the deepest lesson of conviction formation. We do not hold beliefs because they are proven beyond doubt, but because life requires us to. Philosophy, by demanding absolute certainty, may have set a trap for itself.

Hume's skepticism sent shockwaves through philosophy. If he was right, then no belief was ever fully justified, only assumed. Locke's world of measured inquiry became precarious. Descartes' cathedral of certainty collapsed. The search for an indubitable foundation had not led to solid ground, but to emptiness. What had passed for certainty now appeared as a lack of deeper doubt.

Hume's conclusions would strike Immanuel Kant with full force, provoking a response that aimed to rescue a refined version of correspondence and necessity by turning the entire picture upside down.

Conviction Shift: Hume

Hume carried empiricism to its limits. What we call knowledge, he argued, is not grounded in certainty but in habit. Mathematics retains certainty in its internal relations, but beyond that, inquiry resembles casting a line into murky water, hoping to catch something more substantial than driftwood. With Hume, certainty dissolves, leaving probability, and the recognition that conviction persists not because it is proven, but because life cannot proceed without it.

Recap: The Collapse of Certainty

Certainty feels good. When nothing stirs our doubts, when no counterarguments take hold, we feel grounded. We feel sure.

René Descartes wanted to use this feeling of certainty as a foundation for knowledge. What appeared undeniable to him at the end of his methodical doubt, he took to be universally undeniable, for all people, at all times. He had doubted as far as he knew how, and what remained seemed immovable.

He assumed that such certainty must correspond to the world, that it must be truth. His innate idea of God was meant to guarantee this correspondence.

John Locke questioned Descartes' foundation, but not the overall project. He rejected innate ideas, began with a blank slate, and relied on experience and reflection to recover as much certainty as human knowledge would allow.

David Hume took Locke's empiricism seriously, and followed it without restraint. In doing so, he discovered that much of what is called knowledge rests not on reason or necessity, but on custom and habit.

Certainty rose, and then collapsed under its own weight.

Yet truth did not lose its pull. The desire for something unshakable remained.

Immanuel Kant would take up this problem with a remarkable turn.