Unrealizable
ELI5
An "unrealizable" is something real about you — like how others see your personality or your body — that you can never see or feel from the inside the way they do; it's genuinely yours, but you can never quite grab hold of it yourself.
Definition
The "unrealizable" is Sartre's technical term for a specific class of objective characteristics that belong to the for-itself through its being-for-others, yet which the for-itself can never apprehend from within its own first-person perspective. These characteristics are not imaginary or fictitious — they are perfectly real existences — but they are given only to the Other, never to the subject that "is" them. The structural asymmetry is precise: the Other perceives my cowardice, my class, my race, my beauty as stable, thematic predicates; I, as the nihilating for-itself, am always already beyond any such fixity through my projective freedom. I can never coincide with these characteristics as an in-itself would, yet I cannot escape them, since they constitute my "reverse side" — the face I present to the world of the Other that I can never turn to look at directly. The unrealizable thus designates the zone where facticity and being-for-others intersect: it is the form that my alienated being takes when it has become an objective datum for the Other's transcendence.
Crucially, the unrealizable produces a specific existential imperative: because these characteristics are experienced as real yet structurally inaccessible to the for-itself, they are simultaneously given as limits and felt as demands-to-be-realized. Freedom is therefore responsible for a finitude it did not choose and cannot dissolve — including, in Sartre's argument against Heidegger, death itself. Death is not "my" possibility in any authentic Heideggerian sense; it is precisely one of the unrealizables — a synthetic aspect of my reverse side — which belongs to being-for-others and eludes all subjective appropriation. Finitude, by contrast, is constituted by freedom's own projective self-choice, which means freedom remains total not because it overcomes death but because death as an unrealizable is structurally outside freedom's domain.
Place in the corpus
The concept of the unrealizable appears exclusively in jean-paul-sartre-hazel-barnes-being-and-nothingness-an-essay-on-phenomenological, where it functions as a technical specification within Sartre's ontology of the for-itself's relation to the Other. It is best understood as a precise regional concept that sits at the intersection of several major cross-referenced canonicals. Most directly it is a specification of alienation: like the Lacanian vel of alienation, the unrealizable names a constitutive loss built into the very structure of subjectivity — one cannot simultaneously be one's being-for-others and apprehend it. The "forced choice" structure is analogous: choosing subjective transparency (the for-itself's nihilating perspective) means losing access to the stable objective being that the Other sees; choosing to take up that objective being would dissolve the for-itself's freedom. In this sense the unrealizable is Sartre's phenomenological counterpart to the Lacanian split subject ($) — the gap between the subject of enunciation and the subject of the statement.
The unrealizable also intersects with facticity: it is the specifically social-relational dimension of facticity, the portion of unchosen givenness that belongs not to my body or past alone, but to my being-as-seen. It further brushes against anxiety — the unrealizable, as a demand-to-be-realized that can never be met, is a structural engine for that dread of a gap that cannot be closed. The invocation of death as "one of the unrealizables" in Occurrence 2 links the concept to the question of death and its relation to finitude, while the fact that unrealizables are given in the field of the Other's perception gestures toward the Lacanian big Other as the locus where the subject's being is deposited and read back to it in a form it cannot itself access. The concept thus functions as an extension and phenomenological specification of alienation, not its resolution.
Key formulations
Being and Nothingness: An Essay on Phenomenological Ontology (page unknown)
We shall call these characteristics unrealizables. We must be careful not to confuse them with the imaginary. We have to do with perfectly real existences; but those for which these characteristics are really given are not these characteristics, and I who am them can not realize them.
The theoretical weight of the quote rests on the precise asymmetry encoded in "those for which these characteristics are really given are not these characteristics, and I who am them can not realize them" — the split between the one for whom they are given (the Other) and the one who is them (the for-itself) is irreducible, producing a structure in which being and apprehension permanently diverge. The careful distinction from "the imaginary" is equally loaded: it insists that the unrealizable is an ontological, not a psychological, category — these characteristics are real existences, which makes the inaccessibility all the more structurally significant rather than a mere epistemic limitation.