Occasionalism
ELI5
Occasionalism is the idea that your mind and your body don't actually connect directly — something else (like God, or in Lacan's version, language and social rules) is secretly doing the work of linking them up every single time. Žižek uses this to say that the whole system of words, meanings, and social norms is what holds our inner thoughts and outer physical reality together, not any natural glue.
Definition
Occasionalism, as Žižek deploys it in this corpus, is a structural-philosophical concept drawn from Malebranche's 17th-century metaphysics and reread through Lacan's theory of the big Other. In Malebranche's original formulation, God alone is the true cause of all events; finite substances (mind and body) never directly act upon one another — God intervenes at each "occasion" to coordinate the two causally incommensurable series. Žižek strips this of its theological content and replaces God with the big Other, the symbolic order: the big Other is what accounts for the coordination between the network of ideas (mental/symbolic causality) and the network of bodily, "real" causality. Because no immanent or natural bridge connects these two causal chains, their apparent synchrony is always already sustained by a third, external instance — the symbolic order as such.
What makes this move theoretically sharp is the identification Žižek draws between occasionalism and the "arbitrary of the signifier." The gap that separates the two causal networks is precisely the gap the Saussurean-Lacanian signifier introduces: the signifier does not naturally correspond to the real, and thus whatever coordination appears between thought and world, symbol and body, or intention and action, must be "guaranteed" by a structurally external mediator — the big Other. This means occasionalism names not a historical curiosity but a permanent structural condition: the subject's apparent unity of mind and body, will and act, is always a retroactive effect produced by the symbolic order's intervention, not a transparent natural fact. The death drive figures in Žižek's second occurrence as the "vanishing mediator" between nature and the symbolic order, the originary cut that installs this mediation in the first place.
Place in the corpus
This concept appears in two Žižek texts — slavoj-zizek-hegel-in-a-wired-brain-bloomsbury-publishing-2020 and slavoj-zizek-less-than-nothing-hegel-and-the-shadow-of-dialectical-materialism-v — and functions in both as a hinge between Lacanian structural theory and philosophical history. In relation to the cross-referenced canonical concepts, occasionalism is best understood as a specification of the Gap and the Symbolic Order working in tandem: the Gap is the structural openness that prevents any immanent coordination between real causality and symbolic causality, and the Symbolic Order (the big Other) is what steps in to manage — never to close — that gap. It extends the concept of the Signifier's arbitrariness from a formal-linguistic claim into a metaphysical-causal one: not just that signifiers are unmotivated by nature, but that all coordination between mental and physical series presupposes the symbolic order as their mediating ground.
In relation to the big Other and Ideology, occasionalism provides the structural underpinning for why ideological coordination works without any natural necessity: just as God was needed to synchronize Cartesian substances, the big Other is needed to synchronize subjects with their social reality. Interpellation, in this light, is one name for the event of occasionalist coordination — the moment the big Other "hails" the subject and produces the illusion of direct correspondence between identity and social position. And the Real surfaces as what remains uncoordinated, the jouissance that the big Other cannot fully absorb — the residue of the very gap that occasionalism names. In both source texts, occasionalism is not a thesis about historical metaphysics but a structural diagnosis of the mediated, never self-grounding character of symbolic existence.
Key formulations
Hegel in a Wired Brain (p.51)
Occasionalism is thus essentially a name for the 'arbitrary of the signifier,' for the gap that separates the network of ideas from the network of bodily (real) causality, for the fact that it is the big Other which accounts for the coordination of the two networks
The quote is theoretically loaded because it performs three simultaneous identifications in a single sentence: "occasionalism" = "arbitrary of the signifier" = "the big Other as coordinator." The phrase "arbitrary of the signifier" invokes the Saussurean-Lacanian principle that no natural bond ties symbol to world, while "the gap that separates the network of ideas from the network of bodily (real) causality" maps this arbitrariness onto the Lacanian distinction between the Symbolic and the Real — meaning the big Other is not a supplement to an otherwise functional system but the very structural condition that prevents the gap from becoming an abyss of total incoherence.