Looks like I outsmarted myself with this one. Steven Gordon, on the Agile Project Management list, offered definitions that are far simpler and cleaner than mine: A plan is a course of action. Planning is making a plan.

I’ve been thinking a lot about planning, especially about the purposes for planning and about how planning serves those purposes. I tried to stuff all of that into my definitions.

Why plan? To inform decisions about the course of action described in the plan.

How does planning inform those decisions? By making explicit our expectations, assumptions, intentions, constraints, and commitments, so that we can scrutinize them and make inferences from them.

Those ideas about planning—the purposes and benefits—are important ideas. But they aren’t the defining ideas. The defining ideas are the ones Steven suggests: A plan is a course of action. Planning is making a plan.

Why plan?

A lot of people hate to plan. It hems them in, it is constricting, it is pointless since the plans will eventually fail in any event, etc.

But the best reason I have found for planning is that it creates a web of thinking, images, stuff that helps to see those things that are pertinent to what you are trying to accomplish. Without the planning important things would pass by unnoticed. Planning helps catch thoughts to enrich/enable purposeful action.

Dean — I prefer your definition to Steven’s. Maybe that’s because I see a plan not as a simple list of anticipated actions, but something that “[makes] explicit our expectations, assumptions, intentions, constraints, and commitments” as well.

Maybe a plan is a model of the world which defines the meaning of our project. We need a model/abstraction to be able to to even speak coherently about what goes on in the project. This would explain why a plan is very important even though we know it will fail - it defines our expectations, assumptions, intentions, constraints, and commitments - our model of project-world.