The truth is that while analysis is an important part of decision making, analysis without synthesis is almost worthless. The converse is also true.
Dictionaries define analysis as something like the following: the separating of any material or abstract entity into its constituent elements (opposed to synthesis)
Dictionaries define synthesis as something like the following:
The combining of the constituent elements of separate material or abstract entities into a single or unified entity (opposed to analysis).
So while dictionaries define analysis and synthesis as opposites of one another, when it comes to decision making they are necessary complements of one another.
Most organizations have top level managers, mid level managers, supervisory managers, technicians and other experts, each capable of doing an analysis on one or more facets of a complex decision. However, few organizations know how to perform a synthesis of these analyses. In order for an organization to make a rational decision—that is a decision that best achieves the multitude of their objectives, they must be able to synthesize as well as analyze.