Both are contagious. A Stanford psychologist did a telling experiment. Soon everything of value had been stolen from the ratty car. The clean car was untouched. Ratty environments evoke ratty behavior.
Crime really is contagious.
To achieve remission Bratton reduced contact with the disease. We face our own tipping point in education. Public school students come to universities with poorer and poorer math preparation. In math-based colleges like engineering, science, and business we've suddenly reached a point were we must choose between an alarmingly high failure rate or an alarming lowering of standards. Maybe in this case we can recognize a nonlinear tipping point and do something about it.