Biological, economic and social systems abound with both types of system. Darwin noted that a single ground orchid produced enough seeds to fill an acre in the first generation, an English county in the second and the planet in the third. Negative feedback prevents this explosion from happening. Each depend on the other, and no one can develop the way in which the solitary orchid has the potential to do. The second type of classification is concerned with the dynamical nature of the system.
Many systems can be stable or they can oscillate.
The implication is that there are situations in which the system shows one kind of dynamical property stability and another where the same system, with different values of the variables, shows instability. The range which the variables can occupy is known as the state space , and parts of it have well defined properties. One significant kind of instability is called deterministic chaos . In an oscillating system, variables change as with the business cycle but what happens next is relatively predictable. In a chaotic system, the next value of a variable has very little that is obvious to do with the previous state.