A vicious circle (or cycle) is a complex chain of events that reinforces itself through a feedback loop, with detrimental results. It is a system with no tendency toward equilibrium (social, economic, ecological, etc.), at least in the short run. Each iteration of the cycle reinforces the previous one, in an example of positive feedback. A vicious circle will continue in the direction of its momentum until an external factor intervenes to break the cycle. A well-known example of a vicious circle in economics is hyperinflation.
When the results are not detrimental but beneficial, the term virtuous cycle is used instead.
Examples
Vicious circles in the subprime mortgage crisis
The contemporary subprime mortgage crisis is a complex group of vicious circles, both in its genesis and in its manifold outcomes, most notably the late 2000s recession. A specific example is the circle related to housing. As housing prices decline, more homeowners go "underwater", when the market value of a home drops below that of the mortgage on it. This provides an incentive to walk away from the home, increasing defaults and foreclosures. This, in turn, lowers housing values further from over-supply, reinforcing the cycle.
The foreclosures reduce the cash flowing into banks and the value of mortgage-backed securities (MBS) widely held by banks. Banks incur losses and require additional funds, also called "recapitalization". If banks are not capitalized sufficiently to lend, economic activity slows and unemployment increases, which further increase the number of foreclosures. Economist Nouriel Roubini discussed vicious circles in the housing and financial markets in interviews with Charlie Rose in September and October 2008.
Designing ecological virtuous circles
By involving all stakeholders in managing ecological areas, a virtuous circle can be created where improved ecology encourages the actions that maintain and improve the area.
