Describing the prescriptive approach to strategic management is best done by contrasting it with the emergent approach. The former involves identifying the main elements of a strategy and its desired goal at the beginning of the planning process. With the latter approach, the desired goals are not predetermined. Instead, they evolve as the various steps in planning are completed.
The strategic decider -- if not the chief executive officer, then someone near him -- establishes the strategic objectives in a prescriptive approach. They are then disseminated throughout the organization. As with military marching orders, the prescriptive approach is "top down." The main advantage to this approach is that the objectives are clearly defined, and the entire organization has the same understanding of them. The obvious disadvantage is that it tends to be rigid and unresponsive to the challenges and opportunities that often bubble up from within.
Using the emergent approach, those in the organization closest to its customers have input in determining the strategic objectives. It is "bottom up." An emergent strategy is designed to be flexible and responsive to changes in the competitive environment. As new information presents itself, the organization adjusts its strategy on the fly. The biggest disadvantage to the emergent approach is that, unless properly harnessed, it can lead to confusion and result in different factions within the organization pulling in different directions.