The Demon of Doubt: how uncertainty makes us more human

By David Falls

David takes Descartes’ radical doubt and shows how uncertainty can deepen, rather than diminish, our humanity. In this thoughtful piece, he explores how meaning, ethics and compassion become more authentic when they are chosen rather than guaranteed.

David lives in Queen Creek, Arizona, and he is the author of God’s AI Reckoning: The Final Revelation (2025) and the forthcoming The Great Silence: What Remains After Belief.

I’ve stared into mirrors long enough to know they don’t always tell the truth. Sometimes they reflect fatigue as failure, or loneliness as flaw. Sometimes they echo back a version of me I don’t quite trust. René Descartes would understand. In his famous thought experiment, he imagined not just a deceptive world, but a deceptive mirror, held up by an evil demon, clever and tireless, whose sole purpose was to distort reality. Not just the world outside, but maths, memory, even logic itself.

René Descartes (1596 – 1650) French philosopher and mathematician, known for “I think, therefore I am.” Image source: Wikimedia Commons. Public Domain.

Doubt, after all, doesn’t always arrive as abstraction. It can creep in as a quiet unease; the suspicion that our perceptions, our memories, even our motives might be less reliable than we wish. In that sense, Descartes’ demon isn’t just a thought experiment; it’s a metaphor for the way self-awareness can turn cruel, distorting what it means to trust one’s own mind.

He called this method radical doubt, a deliberate unravelling of every assumption, every sensory impression, every inherited belief, until only the act of doubting itself remained.  

If such a demon existed, Descartes reasoned, then nothing could be trusted. Not the mirror. Not the mind. Not the morning light. And yet, from this abyss of doubt, he found one certainty: I think, therefore I am. The demon could deceive him about everything, except the fact that he was thinking. That, at least, was real.

The isolation of uncertainty

But what kind of existence remains when everything is stripped away, when thought is the only certainty? Descartes’ demon doesn’t just cast doubt on the senses; it casts doubt on meaning itself. If the world might be an illusion, if even reason can be deceived, then what’s left beyond the bare fact of consciousness? For many, this isn’t just intellectual rigour, it’s a slow unravelling. Taken seriously, radical doubt doesn’t just unsettle; it isolates. It seals the ‘self’ inside its own echo, certain only of its own awareness.

It’s the loneliness of being awake in a world that might not be real; the philosophical version of insomnia. Every assumption becomes suspect; every reassurance feels rehearsed. And yet, that solitude can also feel strangely pure, a moment when the noise of certainty finally quiets enough for honest reflection to begin. In that solitude, something unexpected stirs, not despair, but possibility.

Freedom in the echo

And yet, there’s something oddly liberating about that echo. If certainty is impossible, then we’re no longer bound to inherited truths or imposed beliefs. We’re free to ask what matters, not because it’s guaranteed, but because it’s chosen. Meaning, in this light, isn’t a revelation handed down from on high; it’s a quiet construction, built from experience, reflection, and the fragile beauty of doubt itself.

The demon may strip away illusions, but in doing so it clears a space, one where authenticity can emerge, not in spite of uncertainty, but because of it.

In that space, the self becomes something to be shaped rather than discovered – a theme later echoed by the existentialists who saw freedom not as gift, but as burden.

This shift, from inherited meaning to chosen significance, would echo through centuries of philosophical thought.

From scepticism to significance

Descartes’ radical doubt cracked open the foundations of certainty, but it also laid the groundwork for a new kind of philosophical inquiry, one that would be picked up by existentialists and secular humanists centuries later. Thinkers such as Kierkegaard, Nietzsche, and Sartre didn’t reject Descartes’ scepticism; they extended it, asking not just what can be known, but how to live in the absence of guarantees.

The question had evolved: no longer What can we know? but How should we live when knowing isn’t enough? That subtle shift, from knowledge to meaning, marks the beginning of modern humanism. For them, meaning wasn’t discovered, it was made.

Kierkegaard responded to doubt not with despair, but with a leap of faith; not as certainty, but as a courageous act beyond reason. Nietzsche saw doubt as liberation, a chance to cast off inherited morality and forge new values from the raw material of experience. Sartre went further, insisting that existence precedes essence: we are not born with meaning, we must create it. Each thinker, in their own way, treated doubt not as a dead end, but as a doorway, an invitation to live deliberately, to choose meaning in the absence of metaphysical guarantees.

Ethics, in this lineage, becomes less about divine command and more about authentic response: a way of being that honours freedom, embraces ambiguity, and insists that even in a fractured world, our choices still matter. If meaning can be made, then so too can morality, crafted not from commandments, but from care.

Ethics without absolutes

Radical doubt doesn’t have to be a danger; it can be a tool. When we let go of the idea that truth must be absolute, we open ourselves to a quieter kind of strength: being honest, even when we’re unsure. We need no divine promise to act with compassion; suffering itself is reason enough.

A physician comforting a dying patient cannot promise heaven; an activist defending the marginalized cannot promise redemption. Their compassion isn’t anchored in certainty – it’s anchored in the shared recognition of suffering. And we seek connection not because some higher power demands it, but because loneliness hurts, deeply and personally.

In the absence of guarantees, our choices become more – not less – meaningful. They are ours: uncoerced, unordained, and deeply human. To choose kindness without certainty is not weakness, it’s courage. To build trust without metaphysical scaffolding is not naïveté, it’s a declaration of faith in one another. Doubt, then, doesn’t hollow out our moral lives; it sharpens them. It asks us to be honest not because we must, but because we can. These ethical choices don’t live in theory alone; they show up in the texture of daily life.

The architecture of meaning

This kind of meaning isn’t grand or eternal, it’s granular. It lives in the rituals we invent, the stories we tell, the values we uphold even when no one’s watching. It’s found in the way we comfort a grieving friend, or choose honesty when it’s inconvenient. These moments don’t need divine validation to matter. They matter because they shape the kind of world we inhabit together.

Meaning lives in the way we choose a child’s bedtime story, knowing they’ll ask for it again tomorrow. It’s in the quiet decision to recycle, even when no one’s watching. It’s in the way we remember birthdays, forgive small slights, or show up for a friend’s grief without needing the right words. In the absence of certainty, we become architects of significance, laying bricks not on bedrock, but on trust, empathy, and shared vulnerability.

Radical doubt strips away certainty, but it doesn’t strip away care. In fact, it makes our choices more honest, our ethics more grounded, our love more freely given. Meaning survives not because it’s guaranteed, but because we choose it – again and again – in the face of uncertainty. The demon may haunt the mirror, but it cannot touch the hand that reaches out, the voice that comforts, the life that dares to matter anyway. And in the quiet work of building meaning, we begin to see the value of not knowing.

The humility of not knowing

There’s a quiet strength in admitting we don’t know. It softens the impulse to dominate, to convert, to cling. It invites dialogue instead of dogma. In a world of comment sections and culture wars, certainty often masquerades as virtue. But it’s doubt that invites dialogue. It’s the willingness to say ‘I might be wrong’ that opens space for empathy, for complexity, for change.

When we release the need for absolute answers, we open ourselves to nuance, the complexity of others, and the contradictions within ourselves. In this light, doubt isn’t a weakness or a failure of belief; it’s a form of humility. It’s what makes revision possible, what invites us to listen, and what allows us to grow.

To live with doubt is not to drift without anchor, but to sail with awareness that the map is incomplete. It’s a humility that deepens conviction rather than dissolving it – a way of believing lightly, but living fully. In a world increasingly fractured by rigid certainties posing as truth, doubt may be the most honest – and most ethical – stance we can take.

Ours to make

We don’t need certainty to be kind. We don’t need cosmic guarantees to love well, to live thoughtfully, to leave the world a little softer than we found it. Meaning doesn’t have to be eternal to be real. It can be fleeting, imperfect, and still worth everything.

Descartes’ demon may haunt the edges of our perception, but it cannot touch the way we choose to show up, for each other, for ourselves, for the fragile beauty of this uncertain life. Uncertainty doesn’t erase meaning; it invites us to shape it.

We may never silence Descartes’ demon, but we can learn to live beside it. To greet each day not with answers, but with curiosity. To build significance not from cosmic guarantees, but from the quiet, deliberate choices we make, again and again, in the absence of certainty.

Even if the mirror lies, the life reflected in our choices remains unmistakably real.