One of the major themes that influences how systems degrade over time is how terrible human beings are at probability. We tend to overestimate the likelihood of events recurring once we have already seen them and underestimate the likelihood of events that have not yet happened. Sidney Dekker, a professor of human factors and system safety, called the outcome of this cognition problem on system safety drift.10 Systems do not generally fail all at once; they “drift” into failure via feedback loops caused by a desire to prevent failure.
