Multi-actor systems and ethics Erik Pruyt Policy Analysis Section, Delft University of Technology, PO Box 5015, 2600GA Delft, The Netherlands E-mail: e.pruyt@tudelft.nl [Pruyt] Received 31 December 2008; received in revised form 19 April 2009; accepted 27 May 2009 Abstract This paper looks at implicit and explicit ethical aspects of research and decision making in complex issues that are characterized by combined systems and multi-actor complexities. These social–technical issues, called multi-actor systems, are so complex that researchers and decision makers need to reduce these complexities. This is mostly achieved by means of implicit assumptions of the research paradigms/methods chosen and explicit omission of multi-actor and/or system aspects. Many of these paradigmatic assumptions and boundary choices are in fact implicit and explicit ethical choices. The goals of this paper are to draw attention to these ethical choices, to reveal their underlying ethical theories and to reflect on appropriate locations and functions of ethics in different strands of multi-actor systems research and decision making. Keywords: multi-actor systems; ethics; paradigms; complex issues 1. Introduction Multi-actor systems are characterized simultaneously by complex actor-related aspects, by complex system-related aspects, often by other complex aspects and their combined effects. Most complex societal problems require attention to be paid to the (physical) system and to the behavior of multiple actors in the decision-making process, and hence, could be considered or labeled multi-actor systems. Decision making and research related to multi-actor systems is difficult. Multi-actor systems are so complex that researchers/decision makers in multi-actor systems necessarily need to reduce the complexity of the multi-actor system by using basic assumptions and by focusing only on a limited number of systems aspects/behaviors and/or multi-actor aspects/behaviors. Too many aspects and their interactions actually need to be considered simultaneously: systems aspects (different dimensions at different levels), actor aspects (interests, strategies, etc.), institutional aspects Intl. Trans. in Op. Res. 17 (2010) 507–520 DOI: 10.1111/j.1475-3995.2009.00729.x INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH r 2010 The Authors. Journal compilation r 2010 International Federation of Operational Research Societies Published by Blackwell Publishing, 9600 Garsington Road, Oxford, OX4 2DQ, UK and 350 Main St, Malden, MA 02148, USA.