Postulate of Determinism

The "Postulate of Determinism" is Zupančič's label for a specific argumentative strategy in Kant's practical philosophy—one that she identifies and names in order to critique and reframe it through a Lacanian lens. The postulate holds that freedom cannot be located in some metaphysical beyond of causal determination; instead, freedom must be understood as emerging precisely within the causal-deterministic order, at the point where that order fails to fully close on itself. Zupančič's move is to show that what looks like a simple denial of psychologism (a "de-psychologizing" of moral agency) is simultaneously a claim about determinism: the subject of freedom is not a transcendent will floating above nature, but rather the correlate of a crack or gap within the causal chain itself. This "crack in the Other" is the structural location where neither cause nor conscience fully accounts for what happens—and it is precisely here that guilt, rather than moral self-congratulation, becomes the paradoxical testimony to the subject's encounter with freedom.

This framing mirrors Lacan's own move of introducing the subject as correlative to the lack in the Other (S(Ⱥ)). Just as the Lacanian subject is not a positive entity but the effect of a failure of closure in the symbolic order, Kantian freedom under this postulate is not a positive faculty but the effect of a failure of closure in the causal order. Guilt—normally associated with transgression—becomes here the subject's mode of registering its participation in that failure, its complicity in a freedom it cannot fully own as an achievement or as an attribute of consciousness.

The Postulate of Determinism appears in alenka-zupancic-ethics-of-the-real-kant-and-lacan-2000 at p.41, where Zupančič is constructing a Lacanian reading of Kantian ethics. It functions as a conceptual label she coins to capture the double gesture in Kant's argument: the refusal to psychologize moral agency and the correlative insistence that freedom operates within, not outside, causal determination. In this way it is an extension of — and a specification of the stakes of — the broader project of the Ethics of Psychoanalysis, which similarly refuses to ground ethics in the psychology of conscience and locates the moral dimension instead at the Real of desire. Where the Ethics of Psychoanalysis names guilt as the only genuine moral failure (giving ground relative to one's desire), the Postulate of Determinism supplies the structural logic for why guilt can carry that weight: the causal chain never closes, and the subject is the name for that non-closure.

The concept also cross-references Lack and the Splitting of the Subject: the "crack in the Other" that the postulate identifies is precisely the site of lack as defined in the canonical corpus — not a contingent absence but the positive void that is the condition of possibility for the subject. The Postulate of Determinism specifies, within the Kantian register, what Lacan calls the subject's emergence at the point where the symbolic order fails to add up. It touches on the Not-all insofar as the causal order, like the masculine universal, is constituted by an exception that simultaneously undermines its totality; and it touches on Jouissance insofar as the "crack" is also the site where the body's surplus satisfaction — irreducible to the clean calculus of practical reason — insists. The postulate thus serves as a hinge concept between Kantian practical philosophy and the Lacanian topology of the split subject and the lacking Other.

Ethics of the Real: Kant and LacanAlenka Zupančič · 2000 (p.41)

Let us call this line of argumentation the 'postulate of de-psychologizing' or the 'postulate of determinism'.

The theoretical load of this sentence lies in its paired naming: by equating "de-psychologizing" with "determinism," Zupančič signals that the removal of psychology from moral agency is not a retreat to mere mechanism but is itself the positive condition for locating freedom — the postulate is deterministic precisely because freedom only becomes legible where the deterministic chain cracks, not where it is suspended. The double label ("or") marks the two faces of the same argumentative move: one faces inward (against the psychologized moral subject), the other faces outward (toward the causal structure within which the subject nonetheless irrupts).