The Founding Reversal

For most of Western philosophy's history, the deepest questions about human beings were answered before any individual arrived on the scene. Plato argued that the soul has a fixed rational nature aiming at the Good. Aristotle said humans are rational animals whose essence, to live according to reason, defines what counts as flourishing. Medieval Christian philosophy added that God creates each soul with a predetermined purpose. Descartes located the essence of the self in thinking substance. Even Kant, who rejected theological foundations, gave reason a fixed, universal structure that shapes experience in advance. The common thread: human nature is settled before any individual makes their first choice.

Existentialism's central move is a wholesale rejection of this. Its slogan, associated above all with Jean-Paul Sartre, is existence precedes essence: you first exist, show up in the world, and only then define yourself through your choices and actions. There is no blueprint. There is no human nature waiting to be fulfilled. There is only the ongoing, irreversible, often anguishing process of becoming who you are.

The intellectual lineage runs from Søren Kierkegaard (1813–1855), who attacked Hegel's grand systematic philosophy for ignoring the individual's personal, passionate, inward relation to existence. Through Friedrich Nietzsche (1844–1900), who announced the death of God and the necessity of creating values from scratch. To Martin Heidegger (1889–1976), who gave the tradition its most rigorous ontological foundation in Being and Time (1927). To Sartre and Simone de Beauvoir in postwar Paris, who made existentialism a cultural movement as much as a philosophy. And to Albert Camus, who, though he consistently rejected the label, articulated its darkest and most honest corollary: the absurd.

Kierkegaard's starting point is the critique of abstraction. Hegel had built a system in which the individual is a moment in the unfolding of Absolute Spirit, history moves through you, and your particular passions and choices are merely the medium through which the universal comes to self-consciousness. Kierkegaard found this insufferable. When you face a genuine existential choice, how to live, what to commit to, whether to leap into faith, the Hegelian system is useless. Abstract truths about Spirit do not help you. What matters is subjective truth: the passionate, inward, personal relationship to what you commit your life to.

Anxiety may be compared with dizziness. He whose eye happens to look down into the yawning abyss becomes dizzy. But what is the reason for this? It is just as much in his own eye as in the abyss, for suppose he had not looked down. Hence, anxiety is the dizziness of freedom, which emerges when the spirit wants to posit the synthesis and freedom looks down into its own possibility, laying hold of finiteness to support itself.

— Søren Kierkegaard, The Concept of Anxiety (1844), trans. Reidar Thomte

Kierkegaard's image is exact: anxiety is not fear of a specific thing, it is the vertigo of pure possibility. When you face a genuine choice, the terrifying truth is that you could do anything. Nothing in your nature, your past, or the structure of the world compels you. Possibility opens like an abyss. This is the lived phenomenology of freedom, not the exhilarating experience of liberation promised by political philosophy, but the nauseating groundlessness of having to choose who to be without any guarantee that the choice is right.

Kierkegaard maps the ways humans typically respond to this anxiety by describing three spheres of existence. The aesthetic sphere: you live for immediate pleasure, novelty, and sensation, you flee the anxiety of commitment by refusing to commit. The ethical sphere: you take on social roles and universal moral obligations, you answer anxiety with duty. But Kierkegaard argues both are ultimately unsatisfying. The aesthetic collapses into boredom; the ethical runs up against its own limits when the universal conflicts with your deepest personal truth. The religious sphere requires what Kierkegaard calls the leap of faith, a passionate, non-rational commitment to the absolute that no system can validate from outside. Abraham's willingness to sacrifice Isaac is the paradigm: no ethical reasoning justifies it; it is a direct, personal relationship with the infinite that suspends the universal.