Heidegger on the Essence of Dasein

The 'essence' of Dasein lies in its existence. — Martin Heidegger, Being and Time, §9

Historical Context

Section 9 of Being and Time (Sein und Zeit, 1927) is titled "The Theme of the Analytic of Dasein" and marks the formal introduction of Dasein as the central concept of Heidegger's existential analytic. Being and Time was published when Heidegger was thirty-seven and serving as a professor at the University of Marburg; it was intended as the first half of a larger project that was never completed. The book opens with a deceptively simple question — the question of the meaning of Being (Sein) — and argues that this question, despite being the foundational question of Western philosophy since the Pre-Socratics, has been forgotten. Heidegger calls this forgetting the "ontological difference": the tradition consistently confused Being with entities, asking what things are rather than what it means for them to be at all.

Heidegger's strategy is to approach Being through the one entity for whom Being is an issue: Dasein, the human being conceived not as a biological organism or a rational subject but as the being whose own existence is a question for it. Section 9 is where Heidegger breaks decisively with the tradition of Western metaphysics, which from Aristotle through Descartes had sought to define entities by their essence — the "what" that makes a thing what it is. Heidegger argues that this essentialist approach fails when applied to Dasein, because Dasein's "what" is not a fixed property but its way of being. The section thus sets the stage for the entire analytic that follows: the analysis of being-in-the-world, care, thrownness, temporality, and ultimately the relation between Dasein's existence and the meaning of Being as such. The work was composed during a period of extraordinary intellectual intensity for Heidegger, influenced by his reading of Husserl's phenomenology, Aristotle's ontology, and early Christian theology, particularly Luther and Augustine.

Meaning

The claim that "the 'essence' of Dasein lies in its existence" means that Dasein cannot be defined by listing its properties or specifying its nature, as one might define a stone or a tree. A stone has an essence — a set of determining characteristics that make it what it is — but its existence (the fact that it is) is logically and ontologically secondary to that essence. Dasein inverts this relationship: what Dasein is cannot be separated from the fact that it is and how it is. Dasein does not instantiate a pre-given form or nature; rather, it constitutes itself through its way of being.

Heidegger immediately qualifies this by noting that the "essence" of Dasein lies in its existence in the sense that Dasein is always already engaged in the world, always projecting possibilities, always interpreting its own being. Dasein is not a thing that happens to exist but an existence that is always already interpreting itself. The scare quotes around "essence" signal Heidegger's awareness that he is using a traditional metaphysical term in a new, anti-essentialist sense. The priority of existence over essence means that Dasein is defined not by what it is but by the fact that it has to be its being — it is always in question for itself, always responsible for the way it exists. Dasein is the being for whom its own being is at issue, and this "being-at-issue" is not a property it possesses but the very structure of its existence.

Philosophical Interpretation

Heidegger's claim that existence precedes essence (in the specific sense he gives it in §9) was taken up and popularised by Jean-Paul Sartre, who made "existence precedes essence" the slogan of existentialism in his 1945 lecture "Existentialism Is a Humanism." Sartre's appropriation, however, transforms Heidegger's ontological claim into an ethical and psychological one: for Sartre, the priority of existence means that human beings are radically free to choose their own nature, whereas Heidegger's point is more narrowly ontological — it concerns the structure of Dasein's being, not a doctrine of free will. Heidegger himself later distanced himself from Sartre's existentialism, arguing in the "Letter on Humanism" (1947) that Sartre had inverted rather than overcome the metaphysical tradition, remaining trapped within the very essentialism he claimed to reject.

The deeper philosophical significance of §9 lies in what Heidegger calls the "ontological difference" — the difference between Being (Sein) and entities (Seiendes). Traditional metaphysics, Heidegger argues, has consistently confused Being with the highest entity (God, the rational subject, the will) and has thus failed to think Being as such. By defining Dasein through existence rather than essence, Heidegger clears the ground for a new kind of inquiry — fundamental ontology — that asks not what entities are but what it means for them to be at all. This break with essentialism also resonates beyond existentialism: it anticipates the anti-foundationalism of post-structuralist thought and the deconstruction of fixed identities in contemporary philosophy, even as Heidegger's own project remained rigorously ontological rather than ethical or political. The claim in §9 is thus not merely a definition of Dasein but a methodological revolution: it declares that the tradition's approach to the question of being has been fundamentally misguided and that a new path — one that begins from existence rather than essence — must be opened.

Related Concepts

• Dasein: the being for whom its own being is an issue; Heidegger's term for human existence
• Ontological Difference: the distinction between Being (Sein) and entities (Seiendes)
• Existence (Existenz): Dasein's way of being, contrasted with mere presence-at-hand
• Essence (Essentia): the traditional metaphysical "what" of a thing, which Heidegger argues is secondary for Dasein
• Fundamental Ontology: Heidegger's project of asking the question of the meaning of Being

Related Learning

• Martin Heidegger — Explore the life and philosophy of Heidegger
• Being and Time — Full analysis of Heidegger's masterwork
• Meaning — The question of meaning in philosophy

Sources

• Heidegger, Martin. Being and Time. Translated by John Macquarrie and Edward Robinson. Section 9. Oxford: Blackwell, 1962.
• "Martin Heidegger." Stanford Encyclopedia of Philosophy. Accessed July 30, 2026. https://plato.stanford.edu/entries/heidegger/