While negative-feedback loops tend to support the stability of a system, positive-feedback loops often create ever-widening crises, which tend to lead to a breakdown of the system (as in the bus system) or to its evolution into a radically different and unintended state (as in a mixed economy). In other cases, however, positive feedback tends to reinforce significant features of the system's original state. For example, a tennis player of above-average ability aspires to become a professional player. Her early successes, as shown in the graph at right, may generate a positive-feedback loop through which she experiences increasing success over time, reinforcing her initial skill and commitment to developing as a professional player. In this case, the effect magnified by positive feedback is not inconsistent with the initial conditions of the system, and in fact it tends to strengthen those conditions. In our previous positive-feedback examples, in contrast, the amplified effect operated against the system's basic structure or intended function, thereby generating some degree of inherent instability.

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