Logic Decay

The failure mode in which agentic logic produces increasingly incorrect outputs not because the code is defective, but because the data environment it was calibrated for has shifted — a miscalibration that compounds silently until it produces a visible error.

Logic Decay is the most insidious of the three primary autonomous system failure modes because it is invisible at the point of origin. A software bug is present from deployment and detectable by testing. Logic Decay is introduced by environmental change after deployment: customer behaviour shifts, market pricing moves, an API updates its schema, regulatory parameters change. The logic gate that produced correct outputs in Q1 continues executing in Q3 — against a data environment it was never calibrated for. Each individual output is plausible. The accumulated drift is not. The error compounds until it produces a failure that is impossible to miss, at which point it has typically been running for weeks.

First used: March 2026