Ontological uncertainty

Ontological uncertainty is uncertainty about what the possibilities are — not merely which outcome will occur, but whether the list of possible outcomes is complete. It is the uncertainty of the intelligence agency that failed to imagine the attack, the regulator that did not contemplate the financial instrument, the virologist that did not predict the pathogen.

Unlike epistemic uncertainty, which can be reduced by more data within an existing model, ontological uncertainty requires new models, new categories, and new forms of imagination. It is related to Knightian uncertainty — unmeasurable uncertainty — but broader: Knightian uncertainty concerns unknown probabilities, while ontological uncertainty concerns unknown possibilities. The only reliable strategy for managing ontological uncertainty is adversarial design: the deliberate cultivation of perspectives that challenge the current framing of what is possible.