Backcasting is a planning methodology where a desired future is defined using either basic principles (i.e. conditions that must be met within the system) or scenarios (i.e. simplified images of the future). An assessment is then made of the current system and strategic actions are identified, prioritized according to their ability to achieve the desired outcome, implemented, and reviewed.
An alternative to traditional forecasting, backcasting is especially useful in uncertain circumstances, when there is a need for a major systemic change, when problems are complex, when the problem is primarily a matter of externalities, when the scope is wide enough and the time frame long enough to enable thoughtful choice, and when dominant systems are part of the problem.