Simple systems: simple systems are situations where essentially inanimate objects interact with each other in ways that are fully understood. Lego is a simple system. So is a cake recipe, or a bungee jump. The components of a simple system don’t fight back. Simple systems are therefore predictable. They can
only go wrong if components fail or you don’t follow instructions. In either case they fail in predictable ways. As such, simple systems are suitable for checklists,[1] recipes etc, where algorithms can overcome the hubris that will surely rain down on the heads of those who treat simple processes as trivial. Disinfecting your instruments before performing heart surgery, for example, is a simple step to take, but not a trivial one.