No philosophical movement of the twentieth century shaped culture, literature, and our self-understanding as profoundly as existentialism. Born amid the wreckage of two world wars, the collapse of metaphysical certainties, and the crisis of traditional institutions, it placed at the heart of philosophy what the great systems had overlooked: the concrete, singular, unrepeatable existence of each individual.
Existentialism is not a school with a uniform set of doctrines. It is better described as a constellation — a cluster of thinkers who, through diverse and sometimes conflicting paths, converge on one conviction: philosophy must begin with lived experience, with anguish, freedom, and the finitude of the human being, rather than with logical abstractions or totalizing systems.
This article traces the entire constellation: from nineteenth-century precursors to postwar developments, through Heidegger’s fundamental ontology, Sartre’s radical freedom, Camus’s absurd, Beauvoir’s ambiguity, and Merleau-Ponty’s embodied philosophy.
1. What is existentialism: definition and central thesis
Existentialism can be defined as the philosophical current that asserts the primacy of existence over essence. In Jean-Paul Sartre’s classic formulation, presented in the lecture Existentialism Is a Humanism (1945): existence precedes essence. This means that human beings are not born with a fixed nature, a predetermined destiny, or a function inscribed in a cosmic order. We exist first — are thrown into the world — and only afterwards define ourselves through what we do, through the choices we make, through the project we sustain.
This reversal carries vast consequences:
- There is no universal human nature dictating what we ought to be. Each person is responsible for inventing themselves.
- Freedom is inescapable — even refusing to choose is itself a choice.
- Anguish accompanies this freedom, for there is no external guarantee that our choices are correct.
- Responsibility is total: we cannot blame God, nature, or society for what we become.
Not every philosopher associated with existentialism accepted this Sartrean formula. Heidegger rejected the label “existentialist”; so did Camus; Marcel preferred “philosophy of existence.” Jaspers used the term Existenzphilosophie. Yet all share a refusal of abstract rationalism and an attentiveness to the concrete, finite, situated condition of the individual.
2. Precursors: Kierkegaard and Dostoevsky
2.1 Kierkegaard: the individual against the system
Existentialism finds its founding moment in Søren Kierkegaard (1813–1855), the Danish philosopher who, at the height of Hegelian idealism, raised the banner of the singular individual against the system.
Hegel had built the most grandiose philosophical edifice of the nineteenth century: a system in which history, logic, nature, and spirit are articulated into a rational totality. Kierkegaard objected that this system, however imposing, forgot something decisive: the existing individual. The concrete person who suffers, doubts, sins, loves, and dies cannot be reduced to a moment in the unfolding of the Absolute Idea.
In The Concept of Anxiety (1844), Kierkegaard describes anxiety as the dizziness of freedom — the feeling that arises when the human being confronts the abyss of their own possibilities. Unlike fear, which has a determinate object, anxiety is objectless: it is vertigo before the possible as such.
In Fear and Trembling (1843), he analyzes the figure of Abraham — the patriarch who obeys the divine command to sacrifice his son Isaac. Kierkegaard sees in this episode the structure of the leap of faith: an act that suspends the universal ethical in the name of an absolute relation with the Absolute. The leap cannot be rationally justified; it demands a radical decision that surpasses the sphere of universal ethics.
Kierkegaard also proposed the three stages of existence: the aesthetic (life oriented by pleasure and novelty), the ethical (commitment to duty and moral universality), and the religious (singular relation with God, beyond reason). The passage between them is not mediated by logic, as in Hegel, but by leaps — existential decisions that break with the previous sphere.
2.2 Dostoevsky: the abyssal freedom
The Russian novelist Fyodor Dostoevsky (1821–1881) did not write philosophical treatises, but his novels explore with unmatched intensity the themes that existentialism would later systematize: freedom as burden, guilt, suffering, and revolt against God.
In The Brothers Karamazov (1880), the character Ivan formulates a dilemma that echoes throughout existentialism: if God does not exist, everything is permitted. Dostoevsky does not celebrate this conclusion — he is horrified by it. But the realization that, without a transcendent foundation, morality hangs in the void is precisely the starting point for Sartre and Camus.
In Notes from Underground (1864), the “underground man” refuses the reduction of the human being to a rational and predictable cog. Against the scientistic optimism of the age, he affirms irrationality, caprice, and voluntary suffering as proof that man is not a piano key.
3. Heidegger: Dasein, being-in-the-world, and authenticity
Martin Heidegger (1889–1976) is the thinker who most radically reformulated the question of existence in the twentieth century — though he rejected the “existentialist” label and criticized Sartre’s reading of his work.
3.1 The question of being
In Being and Time (1927), Heidegger begins with an observation: Western philosophy, since Plato, has forgotten the question of being. It has concerned itself with beings — things, ideas, substances — but has not asked about the meaning of being as such. To reopen this question, Heidegger analyzes the only being that questions being itself: Dasein (“being-there”), that is, the human being in its concrete existence.
3.2 Fundamental structures of Dasein
Dasein is not a Cartesian subject enclosed within itself that later “goes out” to encounter the world. It is, from the outset, being-in-the-world (In-der-Welt-sein): already thrown into a web of meanings, practical relations, tools, and other Daseins. The world is not an external stage — it is constitutive of what we are.
The fundamental structure of Dasein is Care (Sorge), which articulates three dimensions: facticity (we are always already thrown into a situation we did not choose), projection (we exist as possibility, anticipating ourselves toward the future), and falling (Verfallenheit — the tendency to lose oneself in the impersonal everyday).
3.3 The “they” and authenticity
In everyday life, Dasein tends to dissolve into das Man — the “they,” the impersonal, the “one says” and “one does.” In this mode of being, the individual does not decide for themselves: they follow public opinion, common sense, social expectations. This is the mode of inauthenticity.
Authenticity is achieved when Dasein confronts its finitude. Anxiety (Angst) — unlike everyday fear — has no definite object: it reveals the fundamental uncanniness of existing and wrests Dasein from its dispersion in the impersonal. Anxiety opens the possibility for Dasein to take ownership of its ownmost being.
3.4 Being-toward-death
The most extreme possibility is death — the ownmost possibility, certain, indeterminate as to “when,” and non-transferable. No one can die in my place. Resolutely anticipating death is not morbid brooding: it is the condition for Dasein to appropriate its existence as a whole and live authentically.
Heidegger insisted, in the Letter on Humanism (1946), that his fundamental ontology was not a humanist existentialism in Sartre’s sense. The central question was not the human subject and its freedom, but being and its historical disclosure.
4. Karl Jaspers: boundary situations and transcendence
Karl Jaspers (1883–1969), a psychiatrist by training and philosopher by vocation, developed a “philosophy of existence” (Existenzphilosophie) parallel to Heidegger’s but with a different emphasis: where Heidegger focused on the question of being, Jaspers turned toward communication and transcendence.
4.1 Existenz and boundary situations
For Jaspers, human existence (Existenz) cannot be grasped by scientific or objectifying categories. It reveals itself in boundary situations (Grenzsituationen): death, suffering, struggle, and guilt. These are situations that cannot be eliminated, circumvented, or solved — only faced. In confronting them, the human being is summoned to a decision that discloses their deepest freedom.
4.2 Ciphers of transcendence
Transcendence, for Jaspers, is the ultimate horizon that envelops and exceeds all existence — the Encompassing (das Umgreifende). It cannot be known directly or demonstrated logically. It manifests through ciphers — symbols, myths, limit experiences, works of art — that point toward something beyond the objectifiable without ever fixing it in a concept.
4.3 Existential communication
Jaspers holds that truth cannot be reached in isolation. Authentic existence is realized in the encounter with another existence, in a dialogue that demands openness, risk, and mutual recognition. Existential communication is not the exchange of information: it is a loving confrontation between freedoms that mutually challenge each other to become more.
This emphasis on communication distinguishes Jaspers from Heidegger — whose analytic of Dasein has a more solitary tonality — and from Sartre, for whom the other is, above all, a threat to my freedom.
5. Sartre: radical freedom, bad faith, and engagement
Jean-Paul Sartre (1905–1980) is the name most immediately associated with existentialism — and he was the one who turned the movement into a public philosophy, present in the cafés of Paris, in literature, theater, and politics.
5.1 The ontology of Being and Nothingness
In Being and Nothingness (1943), Sartre distinguishes two fundamental modes of being:
- Being-in-itself (en-soi): the being of things — massive, opaque, identical with itself. A stone is a stone, with no internal distance.
- Being-for-itself (pour-soi): the being of human consciousness — which is always consciousness of something and therefore always a nothingness at the heart of being. Consciousness has no substance of its own: it exists as project, as lack, as desire to be.
From this structure freedom follows: because consciousness is nothing fixed, it is condemned to choose. Freedom, for Sartre, is not a property one may or may not possess — it is the very condition of consciousness.
5.2 Bad faith
Bad faith (mauvaise foi) is the attempt to flee freedom by pretending to be determined like a thing. The waiter who plays his role with excessive rigidity, as if he were a waiter by nature; the woman who pretends not to notice the hand holding hers, treating her own body as someone else’s object — these are famous examples from Being and Nothingness. Bad faith is not lying (for the liar knows the truth); it is a conduct in which consciousness deceives itself about its own freedom.
5.3 The look of the other
Sartre analyzes the encounter with the other through the phenomenology of the look. When the other looks at me, I become an object for a freedom I do not control. The other’s gaze fixes me, judges me, assigns me an essence. Hence the celebrated line from the play No Exit (1944): hell is other people — not because human relations are inevitably destructive, but because the other is the mirror in which I discover my objectivity, my facticity, what I am without being able to escape.
5.4 Engagement
In the lecture Existentialism Is a Humanism (1945), Sartre responds to criticisms that existentialism is pessimistic and individualistic. He argues that in choosing, I choose for all humanity — because every act projects an image of what the human being ought to be. Hence responsibility and engagement: philosophy is not neutral contemplation but commitment to the world.
In his later phase (Critique of Dialectical Reason, 1960), Sartre attempted to reconcile existentialism and Marxism, arguing that Marxism is the unsurpassable philosophy of the age but needs existentialism to recover the dimension of subjectivity and individual freedom.
6. Simone de Beauvoir: ambiguity, situation, and gender
Simone de Beauvoir (1908–1986) was not merely Sartre’s intellectual companion — she was an original thinker who developed existentialism in directions Sartre did not explore, particularly in ethics and the analysis of gender oppression.
6.1 The ethics of ambiguity
In The Ethics of Ambiguity (1947), Beauvoir confronts a problem Sartre had left open: if we are radically free, how can we ground an ethics? Her answer begins with the ambiguity of the human condition: we are at once free and situated, subjects and objects, consciousness and body. Ethics consists in assuming this ambiguity — and in willing freedom not only for oneself but for all. Oppression is condemnable because it denies the other’s freedom, reducing them to the condition of a thing.
6.2 The Second Sex
In The Second Sex (1949), Beauvoir applies existentialist categories to the condition of women. The central thesis — “One is not born, but rather becomes, a woman” — argues that femininity is not a biological given but a social and historical construction. Woman has been constituted as Other in relation to man, who sets himself up as universal subject. Women’s liberation requires that women recognize themselves as free, transcendent subjects, refusing the immanence to which culture has condemned them.
Beauvoir uses the Hegelian dialectic of master and slave to describe the relation between the sexes, but goes further: she shows that women’s oppression is peculiar because, unlike the slave, woman has always lived in intimate proximity with the oppressor, which makes collective consciousness-raising more difficult.
7. Camus: the absurd, Sisyphus, and revolt
Albert Camus (1913–1960), French-Algerian writer and philosopher, Nobel laureate in Literature in 1957, rejected the existentialist label. He preferred the term absurdism. Yet his themes — the absurd, revolt, human solidarity in the face of death — are inseparable from the existentialist field.
7.1 The absurd
In The Myth of Sisyphus (1942), Camus defines the absurd as the confrontation between the human desire for meaning and clarity and the irrational silence of the world. The absurd does not reside in the human being or the world taken separately: it arises from the relation between them. We crave unity, reason, eternity; the world is fragmentary, indifferent, mortal. From this disproportion the absurd is born.
7.2 Three responses to the absurd
Camus examines three possible responses: physical suicide (eliminating the one who perceives the absurd — rejected), the leap of faith after Kierkegaard (suppressing the absurd by surrendering to transcendence — rejected as “philosophical suicide”), and revolt — Camus’s answer. To revolt is to go on living and creating despite the absurd, without illusions, in full lucidity. The myth of Sisyphus, condemned to push a boulder up a hill for eternity, is the image of this condition: one must imagine Sisyphus happy.
7.3 The Sartre–Camus polemic
The publication of The Rebel (1951) triggered the break between Camus and Sartre. Camus criticized revolutions that sacrifice concrete lives in the name of a future utopia — implicitly targeting Soviet communism, with which Sartre was still allied. Sartre, through Francis Jeanson in the journal Les Temps Modernes, accused Camus of abstract moralism and refusal of real political engagement. The polemic revealed a deep fissure within existentialism: between revolutionary political commitment (Sartre) and the intransigent defense of individual dignity (Camus).
8. Merleau-Ponty: embodied existentialism
Maurice Merleau-Ponty (1908–1961) brought to existentialism a dimension often neglected by Sartre and Heidegger: the body.
8.1 The primacy of perception
In Phenomenology of Perception (1945), Merleau-Ponty argues that perception is not an act of a disembodied consciousness interpreting sensory data — it is the originary mode of access to the world. To perceive is to be bodily engaged in a situation. The body is not an object among objects: it is the vehicle of being-in-the-world, the zero point of all orientation, the pre-reflective anchorage in which subject and world intertwine.
8.2 The critique of dualism
Merleau-Ponty rejects both Cartesian dualism (mind separated from body) and the idealism of pure consciousness found in Sartre. For him, the subject/object dichotomy is an abstraction subsequent to lived experience. The example of the hand that touches and is touched reveals the irreducible ambiguity between sensing and being sensed — the body is simultaneously subject and object.
8.3 Flesh and intercorporeality
In the late and unfinished work The Visible and the Invisible (published posthumously in 1964), Merleau-Ponty introduces the concept of flesh (chair): neither matter nor spirit, but the common element from which body and world are made. Flesh is the fabric of reversibility between toucher and touched, seer and seen. From this concept follows the notion of intercorporeality — the relation with the other passes not only through the gaze (as in Sartre) but through the intertwining of bodies in a shared perceptual field.
9. Gabriel Marcel: Christian existentialism, mystery, and being
Gabriel Marcel (1889–1973), French dramatist and philosopher, is the leading representative of what has been called Christian existentialism — though he himself preferred the term “neo-Socratism” or “concrete philosophy.”
9.1 Mystery vs. problem
Marcel’s fundamental distinction is between problem and mystery. A problem is something I can place before me, objectify, and solve technically — like a calculation or a mechanical breakdown. A mystery is something in which I am involved — I cannot detach myself from it to analyze it from outside. Existence, love, death, faith are mysteries: the more I interrogate them, the more I discover that I am part of the question.
9.2 Being and having
In Being and Having (1935), Marcel distinguishes two fundamental relations with the world. Having is the relation of possession, exteriority, objectification — treating something (or someone) as an available thing. Being is participation, presence, creative fidelity. Modernity, for Marcel, tends to reduce being to having — and in this reduction the meaning of existence is lost.
9.3 Fidelity, hope, and presence
Marcel values experiences that escape traditional philosophical objectification: fidelity as a creative commitment that transforms me, hope as an openness to what exceeds all prediction, and presence as availability to the other that is irreducible to mere physical proximity. These themes bring him close to Jaspers (in the emphasis on communication) and distance him from Sartre (whose ontology Marcel considered excessively negative).
10. Legacy and contemporary relevance of existentialism
10.1 Cultural influence
Existentialism was perhaps the last philosophical movement to have a massive impact beyond the academy. In the 1940s–1960s, its concepts permeated literature (Camus, Sartre, Beauvoir, Beckett), cinema (Bergman, Antonioni, the Nouvelle Vague), theater (the theater of the absurd of Ionesco and Beckett), and music (the jazz and chanson française of Saint-Germain-des-Prés cafés).
10.2 Philosophical developments
Many later currents are unthinkable without existentialism:
- Hans-Georg Gadamer’s philosophical hermeneutics deepens the historicity Heidegger had foregrounded.
- Jacques Derrida’s deconstruction radicalizes Heidegger’s critique of the metaphysics of presence.
- Second-wave feminism departs directly from Beauvoir.
- Existential psychotherapy (Rollo May, Irvin Yalom, Viktor Frankl) applies insights about anguish, freedom, and meaning to clinical work.
- The ethics of care and the philosophy of vulnerability take up the existentialist attention to the finite, embodied condition of the human being.
10.3 Criticisms and limits
Existentialism also drew sharp criticism. The structuralists (Lévi-Strauss, Foucault in his early phase) challenged the privilege of the individual subject, showing that linguistic, social, and unconscious structures precede and condition freedom. Habermas criticized the lack of an intersubjective social theory. Anglo-Saxon analytic philosophy considered existentialist language vague and unverifiable.
10.4 Contemporary relevance
In a world marked by the climate crisis, artificial intelligence, the erosion of traditional identities, and generalized anxiety, existentialist themes remain urgent. The question of authenticity in an age of social media and perpetual performance; anguish before an uncertain future; individual responsibility within complex systems; the need to find meaning without recourse to absolute certainties — all of this makes existentialism not a historical relic but a living resource for thinking the contemporary human condition.
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