Intersubjective Overdetermination

Intersubjective overdetermination names the logical contradiction that arises when Kantian critical idealism attempts to incorporate the Other as a genuine, organising presence within the field of experience. For Kant, experience is structured by the transcendental subject's own categories; every element within experience is, by definition, subordinate to and constituted by that organising subject-pole. Yet the Other—as a consciousness in its own right—would have to appear as an organising, transcendent unity, a second pole of structured experience that could not be fully reduced to the first subject's categories. To admit this would be to allow experience to be simultaneously organised by two irreducible, transcendent sources: the constituting subject and the Other-as-subject. Sartre identifies this as a contradiction internal to idealism's own logic, a doubling or "over-determination of the phenomenon" that the idealist framework cannot coherently accommodate.

The concept thus functions as a reductio ad absurdum deployed in Sartre's phenomenological ontology: both naïve realism and critical idealism fail to sustain the Other's genuine existence. Realism dissolves the Other into a mere representation when pushed to its limits, while idealism generates an incoherent overdetermination—two incompatible organising principles colliding within a single phenomenal field. This clearing of the theoretical ground prepares the way for a phenomenological rethinking of intersubjectivity, one that must go beyond the subject/object dyad and the primacy of individual consciousness.

This concept appears uniquely in jean-paul-sartre-hazel-barnes-being-and-nothingness-an-essay-on-phenomenological and is best understood as a critical moment within Sartre's phenomenological ontology rather than a positive doctrine. It cross-references the canonical concepts of Consciousness, Phenomenology, Subject, and Subjectivity in a precise way: it identifies the limit of idealist accounts of consciousness — namely, that a consciousness-centred framework cannot coherently situate another consciousness as genuinely Other. This aligns with the corpus's broader diagnosis of phenomenology's blind spot: as the Phenomenology synthesis notes, the Lacanian tradition insists that phenomenology cannot account for what structures experience from a position external to the first-person subject-pole (the gaze as objet a, the symbolic order, the unconscious). Intersubjective overdetermination is, in Sartrean terms, the precise contradiction that makes this blind spot legible from within the phenomenological tradition itself.

The concept also resonates with the canonical treatment of Lack: the impossibility of two organising subjects cohabiting within one experiential field can be read as a structural "hole" in idealism — a gap that cannot be sutured from within that framework. Similarly, the Imaginary register's constitutive méconnaissance is anticipated here: idealism's failure is precisely its capture within a dyadic (ego–world) schema that cannot tolerate the asymmetry introduced by a genuinely transcendent Other. Intersubjective overdetermination thus functions as a phenomenological precursor to, or negative analogue of, the Lacanian argument that the subject is always already displaced by the symbolic Other — an Other that cannot simply appear "within" experience without rupturing its constituting logic.

Being and Nothingness: An Essay on Phenomenological OntologyJean-Paul Sartre · 1943 (page unknown)

The Other therefore can not without contradiction appear to us as organizing our experience; there would be in this an over-determination of the phenomenon.

The phrase "over-determination of the phenomenon" is theoretically loaded because it deploys a structural term — overdetermination, the simultaneous inscription of a single element by more than one incompatible causal or organising chain — to expose idealism's internal incoherence: "organizing our experience" names the transcendental subject's sovereign function, and admitting the Other into that role means the phenomenon would bear two irreducible, contradictory organising sources at once, which idealism's monological framework categorically cannot allow.