Existence precedes Essence

In Sartre's ontology, "existence precedes essence" names the foundational structure of human reality as for-itself: unlike a manufactured object whose concept (essence) precedes its fabrication, the human being first exists — is thrown into the world as sheer facticity — and only subsequently constitutes itself through the projects it freely chooses. Essence, on this account, is not a pre-given logical nature that determines what the for-itself will do; it is retrospectively sedimented from the for-itself's enacted choices. This is why Sartre can write that "Adam is defined by the choice of his ends" rather than by any Leibnizian compossible essence. The contrast with Leibniz is decisive: for Leibniz, possible predicates logically unfold from a subject's complete individual concept, making each act deducible from essence. For Sartre, no such deductive chain exists — freedom is ontologically prior to essence, and the for-itself is always already ahead of itself, constituted by projection toward possibilities rather than by a nature already given.

The practical-theoretical consequence is equally important. Secondary or derivative choices do not follow logically from a "fundamental project" the way theorems follow from axioms; they relate to it as partial structures to a Gestalt totality. This means there exists a genuine domain of "indifferents" — situations where the fundamental project underdetermines the choice — so that freedom remains unconditioned at the moment of choice while remaining retroactively interpretable through the original project. Essence is thus always a temporal achievement: it is what the for-itself has been, never what it is or must be.

This concept appears in the Sartrean strand of the corpus (jean-paul-sartre-hazel-barnes-being-and-nothingness-an-essay-on-phenomenological, p.468) and functions as the ontological ground for everything Sartre means by Freedom (Sartrean), Fundamental Project, and the for-itself's mode of being. It directly underpins the cross-referenced concept of Consciousness: in Sartre's frame, consciousness just is this perpetual nihilating movement beyond any fixed essence, which is why it is radically transparent to itself yet never self-identical. Where the Lacanian corpus systematically decentres consciousness — making it derivative of the unconscious and the symbolic order — Sartre's "existence precedes essence" performs the opposite move: it elevates consciousness/freedom to the role of ontological foundation, refusing any determining essence whether logical (Leibniz), biological, or social. The concept thus stands in constitutive tension with the Lacanian accounts of Consciousness and Fantasy synthesized in this corpus: Lacan's fantasy ($◇a) is precisely the structural frame that gives the subject's desire its "coordinates" — a function that, in Sartrean terms, would be inadmissibly essentializing, imposing a quasi-essence on the for-itself from without.

Within the Sartrean argument itself, "existence precedes essence" also governs the concepts of Singularity and Bad Faith. Singularity (the irreducible particularity of each for-itself's project) is only possible because there is no universal essence constraining individual choices. Bad Faith, conversely, is the self-deceiving flight from this condition — the attempt to treat oneself as if one possessed a fixed essence (being-in-itself) that determines conduct and thereby relieves the anguish of radical freedom. The concept is therefore the axiomatic starting point from which the rest of Sartre's existential psychoanalysis — including Fundamental Project and Reflection — is derived.

Being and Nothingness: An Essay on Phenomenological OntologyJean-Paul Sartre · 1943 (p.468)

Adam is not defined by an essence since for human reality essence comes after existence. Adam is defined by the choice of his ends

The quote is theoretically loaded because it names a concrete individual ("Adam") precisely to displace the Leibnizian logic of individual essences: Adam is not the bearer of a complete concept from which his acts follow, but is constituted entirely by "the choice of his ends" — making teleological self-projection, not essence, the ontological ground of personhood. The phrase "essence comes after existence" encapsulates the entire temporal reversal on which Sartrean freedom depends.