CONCEPT
The Factor of Safety
Engineering's institutionalized acknowledgment of its own ignorance — the deliberate excess built into every structure as a moral commitment to the people who will depend on it, and the specific property that AI optimization is structurally inclined to erode.
Every engineered structure in the world is overbuilt. A factor of safety of two means the structure is designed to carry twice the maximum expected load; a factor of four, four times. The factor varies by application, material, and failure consequence — aircraft wings at 1.5, concrete dams at 4 or more.
Petroski understood this not as a technical parameter to compensate for bad math but as an
epistemological stance: the engineer's confession, built into every structure, that she does not know everything the structure will encounter. The calculations are as precise as possible. The factor exists because the engineer knows the calculations are not sufficient — the model is approximate, materials vary, construction introduces tolerances, and the future will present conditions no model predicted. The factor of safety is the margin within which the unanticipated can be absorbed without catastrophe. AI optimization, whose logic minimizes everything the specification does not explicitly demand, reads this