Søren Kierkegaard's Sygdommen til Døden (The Sickness Unto Death), published in 1849 under the pseudonym Anti-Climacus, is widely regarded as the founding text of existentialist philosophy. Taking its title from Jesus's words at Lazarus's tomb - 'this illness does not lead to death; it is for the glory of God' (John 11:4) - the work argues that true death is not physical but spiritual: it is despair, the failure to become oneself before God. The analysis Kierkegaard develops over the book's two parts is both a phenomenology of the human condition and a theological account of sin, written with a compressed aphoristic intensity that influenced Heidegger, Sartre, Camus, Tillich, and the entire existentialist tradition.
The Thinker and His Work
Kierkegaard published The Sickness Unto Death two years before his death at forty-two, at a period when he had shifted from the pseudonymous aesthetic works (Either/Or, Stages on Life's Way) to increasingly direct Christian communication. The pseudonym Anti-Climacus signals that its author speaks from a higher level of Christian commitment than Kierkegaard himself claimed to have achieved - an ironic distancing that is itself philosophically significant. Kierkegaard regarded himself as a corrective to the cultural Christianity of Christendom, in which everyone is automatically Christian by birth and convention; Anti-Climacus speaks from the demanding height of authentic Christian existence.
Biblical Texts Engaged
John 11:4 provides the title and the philosophical move: Jesus says that Lazarus's physical illness 'does not lead to death,' meaning that there is a condition worse than physical death - the spiritual death of the person who does not come to God. Kierkegaard reads this as a phenomenological clue: the 'sickness unto death' that Anti-Climacus analyzes is not death as ending but despair as a living death, a failure of being that cannot be escaped by physical mortality because it is the self's relationship to itself that has gone wrong.
Romans 7:24 - 'Wretched man that I am! Who will deliver me from this body of death?' - is the Pauline diagnosis that parallels Kierkegaard's analysis. Paul's anguish of the divided will - wanting to do good, doing evil - is the phenomenological texture of despair as Kierkegaard describes it. The self that cannot be what it knows it ought to be, that is defined by this gap between actuality and possibility, is the self in despair.
1 John 3:20 - 'whenever our heart condemns us, God is greater than our heart, and he knows everything' - provides the theological resolution that Kierkegaard's work moves toward: the self's ultimate judge is not its own self-knowledge but God's. This is the ground for the possibility of escaping despair - not through introspective achievement but through transparent self-surrender to the power that constituted the self.
Core Argument
Kierkegaard's opening definition is famous: 'A human being is spirit. But what is spirit? Spirit is the self. But what is the self? The self is a relation that relates itself to its own self, or it is that in the relation [which accounts for it] that the relation relates itself to its own self; the self is not the relation but [consists in the fact] that the relation relates itself to its own self.' (trans. Hong and Hong)
This densely packed formula means: a human being is not simply a relationship between finite and infinite, temporal and eternal, necessity and freedom - it is a self-relating relationship, a being that has a relationship to its own nature. Despair is what happens when this self-relating goes wrong, when the self either fails to acknowledge its own constitution (unconscious despair), refuses to be itself (despair of weakness), or defiantly insists on being itself in rebellion against its Creator (despair of defiance).
The progression from unconscious to weak to defiant despair is both a phenomenological typology and a theological diagnosis: the person who does not know they are in despair is still in despair; the person who wishes to be someone other than who they are is in despair; the person who knows their constitution and rebels against it - who wants to be their own creator rather than a creature - is in the most acute form of despair, which Kierkegaard calls sin.
Intellectual Context
Kierkegaard was writing in explicit critical dialogue with Hegel's philosophy, which had dissolved the individual into the movement of Absolute Spirit and regarded subjective interiority as a moment to be transcended. Against Hegel, Kierkegaard insisted on the irreducibility of the individual, the primacy of subjective passion, and the impossibility of systematizing existence. The Sickness Unto Death is in this respect a counter-phenomenology to Hegel's Phenomenology of Spirit: where Hegel traces the movement of Spirit through various shapes of consciousness, Kierkegaard traces the movement of the individual through forms of self-evasion toward (possible) authentic selfhood.
Reception and Critique
Heidegger's Being and Time (1927) transforms Kierkegaard's analysis of despair into the secular concept of Angst (anxiety): anxiety is the mood in which Dasein confronts its own groundlessness, its being-toward-death, its radical freedom and finitude. Heidegger rarely cites Kierkegaard directly, but scholars from Karl Lowith to Michael Theunissen have shown the depth of the debt. Sartre's concept of bad faith - the evasion of one's radical freedom through pretending to be determined by one's situation - is structurally identical to Kierkegaard's weak despair, though Sartre removes the theological framework.
Rollo May's The Meaning of Anxiety (1950) and The Courage to Create (1975) brought Kierkegaard's analysis into clinical psychology, identifying anxiety with the confrontation with possibility and creativity. May's neo-Kierkegaardian psychology influenced humanistic psychology and the existential therapy movement.
Legacy
The Sickness Unto Death established the vocabulary of existentialist philosophy: despair, anxiety, authenticity, selfhood, the individual. It demonstrated that philosophical anthropology - the question of what it is to be a human being - could only be addressed through the concrete phenomenology of actual human experience, not through abstract definition. This methodological commitment is the inheritance that Heidegger, Sartre, Beauvoir, and Camus received from Kierkegaard.
Key Passages
'The most common form of despair is not being who you are.' (The Sickness Unto Death, Part One, C., trans. Hong and Hong)
'In spite of all this despair, he cannot die; "the sickness unto death" is literally unable to die, because the second death, dying to die, is to live, to experience that one has died.' (Part One, A.)
Contemporary Relevance
The Sickness Unto Death has acquired new urgency in the context of contemporary mental health crises, particularly among young people. Kierkegaard's diagnosis of despair as a failure of self-relation - not primarily a mood but a structural misrelation - provides a framework for thinking about depression, anxiety, and identity confusion that transcends the merely clinical. His insistence that the self cannot constitute itself - that authentic selfhood requires a power beyond the self - challenges both the therapeutic culture's faith in self-construction and the political culture's faith in autonomous self-determination. The work is regularly assigned in courses on philosophy of mind, ethics, and psychology precisely because it addresses the fundamental question of what it means to be a self with an urgency and precision that has not been surpassed.