From the book, Change By Design by Tim Brown:
The mark of a designer, as the legendary Charles Eames said often, is a willing embrace of constraints.
The willing and even enthusiastic acceptance of competing constraints is the foundation of design thinking. The first stage of the design process is often about discovering which constraints are important and establishing a framework for evaluating them. Constraints can best be visualized in terms of three overlapping criteria for successful ideas: feasibility (what is functionally possible within the foreseeable future) ; viability (what is likely to become part of a sustainable model); and desirability (what makes sense to people and for people).
A competent designer will resolve each of these three constraints, but a design thinker will bring them into a harmonious balance.
Insofar as it is open-ended, open-minded, and iterative, a process fed by design thinking will feel chaotic to those experiencing it for the first time. But over the life of a project, it invariably comes to make sense and achieves results that differ markedly from the linear, milestone-based processes that define traditional business practices.