(Problem Definition, Design Scope)
The project statement should scope the problem space in terms that avoid preconceived solutions, but in a way that all of the design team members (and the customer) can agree and buy into it.
The overall project statement can be further explicated in more or less formal terms. Some designers rigorously document the issues to be addressed by the design project, including constraints, objectives and directives, background and arguments, etc.
In this way, the goals of the project are explicit.
Without such an exercise, the goals are often skewed by dominant personalities rather than all those with insight into the design problem.
Thinking in terms of functions allows the analysis to be specific and informational while sufficiently abstract to lend itself to suspended judgment, lateral thinking and creative solutions.
After settling on a good project statement where the goals are clear, the design team continues with a functional analysis of the problem space. As in the project statement, it is important to avoid thinking in terms of preconceived solutions or existing structures.
Thinking in terms of functions allows the analysis to be specific and informational while sufficiently abstract to lend itself to suspended judgment, lateral thinking and creative solutions.
To illustrate: facilitating the function of "trash removal" rather than providing a "garbage can" opens up a broader range of solutions, for example, recycling bins or preventive solutions that reduce trash via reusable packaging.
If the project is to invent an entirely new system the design team may begin with a top-down analysis of required functions.
If the project is to improve an existing system, the analysis may begin with a structural model (a hierarchical breakdown of components), but even then, the components should be defined in terms of their functions.
Furthermore, they are often stated so vaguely (if at all) that those working on the project have radically different ideas about where they are going.