Towards a theory of MCDM: stepping away from social choice theory

The similarity between aggregation procedures in social choice theory and multicriteria decision aiding is well-known : the alternatives play the role of the candidates, the criteria play the role of the voters and the decision-maker plays the role of the society. Many authors, aware of this similarity, have used the formalism of social choice theory in multi-criteria decision aiding; see for example (Arrow & Raynaud, 1986; Bouyssou, 1992; Durand & Trentesaux, 2000; Fishburn, 1978; Lansdowne, 1996; Marchant, 1996; Nurmi & Meskanen, 1968; Pérez & Barba-Romero, 1995; Perny, 1992; Vansnick, 1986; Vincke, 1982). They transposed, adapted or generalized some results of social choice theory into the more recent context of multi-criteria decision aiding. When the required result was not available in social choice theory, they created it in multi-criteria decision aiding while still using the formalism of social choice theory. The above-mentioned results are mostly characterizations of aggregation procedures. They tell us what the fundamental characteristics of an aggregation procedure are. This approach to the analysis and characterization of aggregation procedures has often been used for so-called outranking methods. It has considerably improved our understanding of these methods but, nevertheless, it suffers some limitations due to the differences between an election and a decision aiding process. We list four of these differences.