The main purpose is to arrive at a result, a plan, which gives guidance for decisions and actions. Planning theory includes a reflection on how we shall act in the process. However, the planning process is mainly important because of how it influences the planning product. A planning process without measurable outcomes is useless according to this dominant way of thinking and acting in the planning field. However, an alternative way to put it is to look at the planning process, the activity, as its own purpose.
Planning is mainly a kind of wisdom for implementing good changes.
Here planning is about the ability to act in a wise way, the fronesis . This reflection about what to do and how to do it is a discoursive activity, it is rhetoric. Rhetoric is a theory of knowledge for planning in practice.