Dan Herbatschek
Søren Kierkegaard was a singular figure. Alongside Nietzsche, he stands as one of the two 19th-century roots of what would later grow into 20th-century existentialism. The two could not be more different—Kierkegaard deeply religious, Nietzsche fiercely antireligious—yet both were brilliant stylists and solitary minds who frame the movement like opposite bookends. Still, Kierkegaard is even harder to place than Nietzsche, for his thought seems to emerge without real forerunners. His philosophy developed less from inspiration than from opposition, shaped by what he rejected and sought to escape. At the heart of his work lies a single pressing question: what does it mean to be a Christian? In what follows, we’ll explore the intellectual climate he resisted, the central ideas he advanced—especially those in his seminal work Fear and Trembling—and finally, the influence he left behind.
Much like Rousseau, Kierkegaard was a critic of modern life, though he wrote a century later, in an age increasingly shaped by cosmopolitanism, science, and industrial growth. Rousseau had argued that cultural progress did not amount to moral progress; Kierkegaard, in parallel fashion, insisted that it also did not signify spiritual or religious progress. His opposition was not directed at secularism—still not fully explicit in his time, since it makes more sense to date the rise of secular modernity to the later 19th century rather than the mid-19th century when Kierkegaard was writing—but at a Christianity reshaped to fit the demands of Reason. Above all, this rationalized version of the faith was represented by Hegel. Kierkegaard’s critique was aimed not at atheists or nonbelievers, but at Christians he thought had profoundly misunderstood their own religion. His message to a still largely Christian Europe was simple and radical: it did not truly grasp what Christianity meant.
Kierkegaard was also the most intricate philosophical writer since Plato—not because his prose was opaque like Kant’s or Hegel’s, but because he deliberately concealed his own voice behind pseudonyms. Like Plato, who presented arguments through his characters, Kierkegaard rarely spoke directly. Almost all of his works were written in the names of imagined figures, each embodying a perspective, and this strategy gave his writings an ironic and aesthetic character.
Born the son of a deeply religious father, Kierkegaard wrestled throughout his life with what it meant to be a Christian. Financially, he lived off an inheritance that sustained him until his death. Socially, he was isolated—recognized in Denmark, yet also mocked. Anecdotes (perhaps exaggerated) tell of children in Copenhagen chasing him through the streets, taunting him with chants of one of his book titles: “Either/Or, Either/Or!”
The defining moment of his personal life came at age 28, when he ended his engagement to Regine Olsen after three years. He concluded that marriage was incompatible with his calling. To Kierkegaard, his mission of uncovering Christianity’s true meaning demanded a particular way of life, and the obligations of marriage would have undermined that vocation.
Kierkegaard had a deep disdain for Hegel; he is perhaps the clearest representative of the mid-19th-century backlash against Hegelian philosophy. At one point, Kierkegaard remarked that if Hegel had written his Logic—one of his key works—and then admitted in the preface that it was merely a thought experiment, he would have been “the greatest thinker who ever lived.” But since Hegel presented it as truth, Kierkegaard concluded, he was “merely comic.” That remains one of the sharpest barbs ever delivered by one philosopher at another.
What infuriated Kierkegaard was Hegel’s drive to systematically subsume every dimension of human life—what Hegel himself called the “shapes of spirit”—into one unified system. For Hegel, nothing was beyond synthesis; every experience and aspect of reality could be reconciled into a comprehensive whole. Kierkegaard, by contrast, saw life as fractured. Human existence consists of distinct modes of living that cannot be harmonized. The individual must therefore make genuine choices—irreducible decisions between incompatible ways of life. This insistence on the necessity of choice is a cornerstone of Kierkegaard’s existentialist legacy.
He outlined three broad categories of existence. The first is the aesthetic life. This way of living revolves around pleasure—or more precisely, around whatever is interesting. It is fundamentally self-centered, though not necessarily immoral. Rather, it is amoral: it pursues its aims without concern for morality. The purest illustration of this comes in his literary masterpiece, Diary of a Seducer. There, Kierkegaard sketches a man who meticulously plots his entrance into a woman’s life—first arranging to be seen on the edges of her vision, then engineering a chance encounter, then ensuring a friend casually mentions his name. Gradually he insinuates himself into her world, causes her to fall in love with him, and then abandons her forever. The seducer’s goal is not cruelty but novelty—he acts out of a relentless pursuit of what is “interesting.”
The second category is the ethical life. This is the ordinary, social way of living, governed by reason and shared norms. In this mode, we justify our actions in terms that others can recognize, and we aim for harmony with those around us. Most people live primarily within this ethical framework. That doesn’t mean we never fail, but our lives are structured by moral rules and mutual understanding.
Within this stage, Kierkegaard describes an extreme figure: the knight of infinite resignation. Such a person is capable of surrendering every personal hope or desire, giving up all aesthetic satisfactions, for the sake of a moral duty. Not everyone can reach this level of ethical consciousness, but for Kierkegaard it represents its highest expression.
The third and highest stage of existence, for Kierkegaard, is the religious life. Unlike Hegel’s system, this third stage is not a reconciliation or synthesis of the first two. That alone signals how far Kierkegaard stands from Hegel—not just in his mocking comments, but in the very architecture of his thought. Hegel’s triads always resolved in a synthesis that integrated opposites; Kierkegaard’s triad resists that logic. The religious does not mediate between the aesthetic and the ethical. Instead, it stands apart, more akin to the aesthetic in its individualism, but infinitely deeper: it is the solitary, unmediated relation between the individual and God.
To recap: the aesthetic is the pursuit of pleasure, novelty, and the interesting; it may be refined but remains self-focused. The ethical is social and rational, embedded in human community and shared norms. But the religious transcends both: it is neither social like the ethical nor sensual like the aesthetic. Its essence lies in the individual’s absolute relation to God.
This becomes Kierkegaard’s central mission—to grasp the nature of this third stage, the religious life. His claim is that it has never truly been understood, and that Hegel’s attempt to fold religion into reason and society only obscured it further. Kierkegaard even confesses, in one of his writings, that while his age prides itself on sophistication—everyone reading Hegel’s Logic and Encyclopedia, marveling at scientific discoveries, inventing new machines for convenience—he remains stuck on the fundamentals. “I do not even understand Abraham and his faith,” he admits. That, he insists, is the mystery he wants to understand.
His pseudonymous voices acknowledge their own aesthetic tendencies, since Kierkegaard believes the religious cannot properly speak for itself. By its nature, it resists direct explanation. And the ethical perspective, he argues, is constitutionally incapable of grasping the religious. These are startling claims. We are used to thinking of religion and ethics as intertwined; Kierkegaard flatly denies this. To interpret religion ethically is to misinterpret it. The two stand worlds apart. For Kierkegaard, the biblical God demands acts that overturn ordinary moral reasoning. Even the central Christian command—forgiveness—is, in human terms, “unethical.”
Let’s pause to ask why Kierkegaard would go so far as to call forgiveness “unethical.” At first glance, this seems outrageous—forgiveness is celebrated in Christianity and many other religions as the pinnacle of moral life. Yet Kierkegaard insists otherwise. Ethics, he argues, rests on the rules of justice: wrong actions demand punishment, and those rules are binding. Forgiveness, however, interrupts this structure. It cancels justice’s demand by telling the guilty: even though you deserve punishment, you will not receive it. In Kierkegaard’s terms, forgiveness is the religious breaking into the ethical domain and overturning one of its fundamental principles.
And it gets more radical still. For Kierkegaard, religious faith cannot be reconciled with Reason, contrary to the claims of Hegel and the medieval Scholastic tradition. Recall that Thomas Aquinas in the 13th century had famously attempted to unite Christianity with Aristotle, arguing that Reason and faith complemented each other. Aquinas believed that rational inquiry into creation—the order and beauty of the natural world—was itself a form of worship, a way of moving closer to God. Across much of Western history, especially during its more optimistic periods, faith and Reason were viewed as harmonious, two powers of the human spirit working in concert.
Kierkegaard is uncompromising in rejecting this. Faith, he insists, is not simply beyond reason (arational)—it is actually against reason. It is irrational. This is a bold and unsettling claim.
Another hallmark of Kierkegaard’s thought is his insistence that “truth is subjectivity.” For him, truth is not primarily about objective reality but about the lived, inward experience of the individual subject. He makes this point forcefully in Concluding Unscientific Postscript. What matters in philosophy, he says, are not abstract descriptions of the world but the questions that compel a person to confront how he or she will live. Scientific, objective knowledge is thereby demoted to second-class status. Being human, Kierkegaard argues, cannot be understood through the methods of science. The inner life is fundamentally different from the outer world.
This emphasis on subjectivity was one reason Kierkegaard became so important for later thinkers, especially the early phenomenologists such as Martin Heidegger. For them, as for Kierkegaard, the ultimate philosophical question is about a way of life—and a way of life is not a purely intellectual matter but a passionate one. Choosing between the aesthetic, ethical, and religious modes of existence is not a decision that science or reason can settle. It is, instead, a matter of human existence itself: I must decide, I must commit, I must “bet” on one path of life, even without certainty.
Let’s turn now to Kierkegaard’s most famous illustration of such a choice, drawn from his masterpiece Fear and Trembling. In that book, he takes the biblical Abraham as the model of what he calls the knight of faith. You’ll recall the story: Isaac, Abraham’s beloved and long-awaited son, born in his old age, is demanded of him by God. Abraham is commanded to sacrifice Isaac, and he sets out to obey. Kierkegaard’s pressing question—characteristic of his approach in this strikingly beautiful text—is: what is happening within Abraham as he climbs the mountain, knife in hand, prepared to kill his only son? What is Abraham saying to himself to make sense of his action? That is what Kierkegaard longs to grasp. And here we see again how he differs from other philosophers—while they concern themselves with universal principles, the progress of science, or abstract metaphysics, Kierkegaard lingers in the Old Testament, struggling to comprehend Abraham.
First, he rules out a common interpretation: Abraham does not treat the ordeal as a divine prank or a mere test, as though he were secretly confident that God would not require him to go through with it. Second, Abraham’s stance is not one of tragic resignation either. If it were, he would be what Kierkegaard calls a knight of infinite resignation. That attitude would be fully rational, even philosophical, and comparable to the Buddha’s claim that all life is suffering. Abraham might have said: “I was wrong to love my son so deeply. Everything is fleeting. I will obey God’s command, and though it breaks me, I resign myself.” Such a view is intelligible—it accepts the loss and suppresses attachment. In Kierkegaard’s framework, that would count as an ethical response, a surrender of personal desire in obedience to a higher necessity.
But Kierkegaard insists that Abraham’s position is different, stranger, and more paradoxical. Abraham must believe both that he will kill Isaac and that he will somehow still keep Isaac—that Isaac will live. He walks up the mountain convinced that he will plunge the knife into his son, and simultaneously convinced that he will not lose him. To our ears this is contradictory, even absurd—and Kierkegaard agrees. This is precisely what makes it faith. Faith, he says, is not compatible with Reason; it is literally irrational. The Latin phrase credo quia absurdum—“I believe because it is absurd”—though wrongly attributed to Tertullian, captures Kierkegaard’s view more closely than that of any other modern thinker. Faith is the commitment to something that defies reason.
With this in mind, we can better see why faith stands apart from ethics. God’s command to Abraham—to kill his innocent son—is, by ordinary ethical standards, monstrously wrong. Just as forgiveness subverts the demands of justice, God’s command lifts Abraham out of the moral order altogether. Religion, for Kierkegaard, intrudes into the ethical sphere only to suspend and overturn it. And because faith is essentially a solitary relation between the individual and God, it cannot be mediated, justified, or even communicated to others. It is incommensurable with the social world, with rationality, and with ethics itself.
Kierkegaard is making a sharp point here, one that feels surprisingly modern. I don’t mean his insistence on irrationalism, but rather his observation that rationality is tied to the social. To act rationally is to be able to give reasons that others can recognize, to justify oneself in a way that makes sense to a community. Rationality, in this sense, requires communication.
Faith, by contrast, is none of these things. It is not rational, not social, and it cannot be communicated. Because of this, a knight of faith cannot be identified by any outward behavior. Take Abraham: he could never explain his action to another person. Nobody would understand him, because what he was doing was irrational by every human standard. Likewise, you could not point to any external sign that marks someone as a knight of faith. Kierkegaard has a marvelous passage where he says that the knight of faith might look no different from an ordinary tax collector. He wakes up in the morning, washes his face and hands, skims the newspaper, drinks his coffee, and goes to work. To outside observers searching for some trace of transcendence in his behavior, there is nothing to find. The inward reality of faith has no outward signature.
Kierkegaard’s sharp separation of the aesthetic, the ethical, and the religious—as incommensurable forms of life—creates real difficulties in understanding him. It also explains his curious literary strategy. His use of pseudonyms was not accidental. Because these spheres of existence cannot be reconciled, he needed different voices to explore them. In Fear and Trembling, for instance, the narrator is explicitly aesthetic. He admits openly: “I am an aesthetic character; I find Abraham’s faith fascinating and puzzling. I cannot grasp it, nor do I see how anyone could.” From Kierkegaard’s standpoint, only a true knight of faith could understand another knight of faith, and such figures are vanishingly rare. For the rest of us, we can only view them from the outside—through the aesthetic lens, or the ethical one. Both are distortions, but Kierkegaard suggests that the aesthetic point of view, strangely enough, gets us closer to glimpsing the religious than the ethical does.
This raises a further problem: if these forms of life are incommensurable, how can one ever move from one to another? How does someone transition from the aesthetic to the ethical, or more radically, from the aesthetic to the religious? Kierkegaard insists that there is no gradual ladder, no dialectical progression, no educational path that carries us from one to the next. Unlike Hegel, who always resolved opposites into a synthesis, Kierkegaard divides existence into starkly separate possibilities. The religious does not absorb or reconcile the other two; it is wholly other.
That is why Kierkegaard titled one of his most famous works Either/Or. As the (perhaps apocryphal) story goes, children in Copenhagen would tease him by shouting this title as he passed. The phrase captures his conviction: when it comes to ultimate ways of life, you must simply choose. And this choice is groundless, without reasons. Why? Because any reasons you might give are drawn from within the form of life you already inhabit. If you are living ethically, the ethical mode can only offer reasons to remain ethical, not reasons to leave it. The gulf between forms of existence is unbridgeable, and choice comes down to a leap.
Does this logical impasse trouble Kierkegaard? Not at all. His reply is consistent: of course it makes no sense—it is irrational. And that is precisely the point.
To conclude: Kierkegaard occupies a singular place among modern thinkers. Many philosophers—especially those tied to 20th-century existentialism—flirted with irrationalism. William Barrett even titled his classic overview of existentialism Irrational Man, pointing to how central the so-called irrational became for this tradition. Yet Kierkegaard stands apart. He is the most sophisticated and relentless critic of rationality in modern philosophy, and at the same time one of the most passionate, emotionally charged writers the field has ever produced.
What, then, is his legacy? In the 20th century, Kierkegaard left two distinct marks. On one side, he deeply influenced liberal Protestant theology, inspiring a movement within religious thought. On the other, though he was too unusual to shape mainstream philosophy widely, his existential view of religion had a surprising impact on the century’s leading atheist existentialist, Martin Heidegger. Heidegger leaned heavily on Kierkegaard’s insights in his landmark book Being and Time.
So what can we finally say about Søren Kierkegaard? Above all, he achieved the aim he set for himself. He crafted a philosophy that was personal to its core, a philosophy centered on subjective truth—truth bound up with the most profound and agonizing choices of human existence. Rejecting the standards of conventional rationalism, Kierkegaard turned philosophy back toward the life of the individual: a single finite life, filled with decisive moments that shape its meaning. If one were to ask Kierkegaard, “What should I do?” his counsel, in the end, would likely be distilled to a single imperative: choose.
