Nonessential Objectives and Network-Based Multicriteria Decision Making Thomas Hanne Fraunhofer Institute for Industrial Mathematics (ITWM) Department of Optimization Europaallee 10 67657 Kaiserslautern Germany e-mail: hanne@itwm.fhg.de Abstract In Gal and Hanne (1999) the problem of using several methods to solve a multiple criteria decision making (MCDM) problem with linear objective functions after dropping nonessential objectives is analyzed. It turned out that the solution does not need be the same when using various methods for solving the system containing the nonessential objectives or not. In this paper we consider this problem for an approach for combining MCDM methods called MCDM networks. We argue that redundancies such as nonessential objectives might be hardly avoidable in complex decision making processes. On the other hand, dropping nonessential objectives should do no harm as an axiom-based analysis of the rationality of corresponding methods shows. In contrast to the previous results on nonessential objectives, the current paper focuses on discrete MCDM problems which are also denoted as multiple attribute decision making (MADM) problems. Key words: Multiple criteria decision making, multiple attribute decision making, modelling, redundancy, nonessential objectives, MCDM networks