Chapter 3 The Decision: The Multi-criteria Universe

Deciding means choosing. This choice concerns “the” solution – alternative – to a problem previously posed in terms that call for it to be solved. Formulated in this way, the verb “to choose” may appear to acquire an unusual synonym: to solve. More precisely, if the solution to the problem posed exists and is unique, it will be determined immediately and the choice will then make sense. This choice becomes “systematic”, not dependent on the decision-maker, when a method exists making it possible to decide the solution univocally. Nevertheless, there are situations for which application of such methods cannot be envisaged, because of the presence of a set of potential solutions or indeed problems, the reality of which differs from that of a model that lends itself to this. In such cases, determining the solution will require a pathway and will become the result of a mechanism based on the decision-maker’s knowledge and intent, and involves “reflecting, discussing, organizing and, finally, choosing” (see Preface). By relying on Simon’s process or one of its variants (see section 2.6.4), the decision-maker will then be aided to rationalize the mechanism that allows them to carry out this analysis. This is the essence of what we have retained from Chapter 2.