I suggest that for the interaction designer, stories provide one way to deal with this indeterminacy. When first starting out, stories provide a way of getting a feel for the new terrain. A key element of the power of stories, I believe, is their informality. Like the first rough sketches of an architect, stories have a sort of discountability. We all know that stories are subjective, exaggerated, and particular, and so we don't take them too seriously.
Any story is liable to questioning, reinterpretation, or rejection.
At the same time, stories provide concrete examples that people from vastly different backgrounds can relate to. Thus, as a collection of stories accretes around a design project, it provides a common ground, a body of knowledge which can be added to, and questioned by, all participants. Y.Y. A 'Pile' Metaphor for Supporting Casual Organization of Information. Permission to make digital or hard copies of part or all of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. Copyrights for components of this work owned by others than ACM must be honored.