The thinking processes are a series of cause-and-effect mapping techniques designed to help managers and staff think through the steps necessary to reaching a goal. They are part of a wider philosophy of business management known as Goldratt's theory of constraints. In order to decide what needs to change, business people create a current reality tree. The evaporating-cloud and future-reality tree techniques are used to decide what to change, while the negative-branches concept helps business people recognize the unintended negative side effects of the change. Finally, a prerequisite tree and transition tree are used to show the step-by-step changes that must be made in order to reach the goal.
If a business finds that it is not meeting all of its goals, managers try to decide what they can change in order to overcome the problem. The current reality tree is a chart made up of boxes and arrows that show how one part of the system affects another. It is used to identify what Goldratt called undesirable effects (UDE), parts of the system that are not working. Once these are identified, managers can find the root constraint, or underlying issue, that causes these UDE.
The next step in the thinking processes involves identifying the underlying assumptions and conflicts that cause the UDE. This is done using the evaporating cloud technique, a chart that starts with the objective and maps the requirements and prerequisites necessary to reach that objective. Then the future reality tree is used to map how changing one element will affect the whole system. This may result in negative branches. If the negative branches can be overcome, the managers have found what they will change. If not, they must search for another solution.
The last two thinking processes are used to show staff how to make the change. The prerequisite tree maps out the actions that must be taken and the obstacles that will result from those actions. It is basically a series of goals and the problems resulting from meeting each one. The transition tree shows a step-by-step explanation of each action and explains why it is needed.
Dr. Eliyahu M. Goldratt first introduced the thinking processes in his book The Goal, published in 1984. They were part of his theory of constraints. This theory assumes that any system is limited by a small number of constraints that keep it from reaching its goals. If these constraints are properly identified using the thinking processes, they can be overcome and the goals of the system can be met.