Definition
An all-or-none process is one in which missing a single critical step erases the value of completing the others. Gawande borrows the term from engineering. The examples he gives are concrete: running to the store to buy ingredients for a cake (forget the flour and the trip was wasted), preparing an airplane for takeoff (one missed configuration check and the rest do not save the plane), evaluating a sick person in the hospital (one missed vital sign and the others may look reassuring while the patient is in danger).
The category is important because it identifies the class of work that most needs checklist defence — the work where the cost of a single omission is catastrophic rather than incremental.
Why it matters
How it works
The diagnostic is straightforward. Ask, for a given process: if a competent operator misses one of the steps, does the rest of the work still create value? If yes, the process is incremental — partial completion produces partial benefit, and a checklist is helpful but not critical. If no, the process is all-or-none — every completed step but the missed one was wasted effort, and a checklist (or a similar structural defence) is what stands between competent operators and catastrophic outcomes.
The combination of all-or-none structure and routine repetition is particularly dangerous. The same step gets performed dozens of times, usually without consequence; over time, an operator starts to drop it on the assumption that "it never matters." Until the one time it does. Gawande's "this has never been a problem before" — heard from pilots, doctors, engineers — is the canonical signal that this drift is happening.