My method is better!

Abstract

Engineering Design is an activity where what you want to create and how you want to create are fundamental to the underlying process. Both aspects of this activity require selection among alternatives that are intertwined. In engineering, how a problem is defined and the creation and selection of alternatives are the focus of methods performed in a team. How do we carry it out, are we content with the outcome, can we do it better, are important questions to address. These questions have been studied to varying depths in many disciplines including psychology, neurosciences, economics, management, non-fiction literature, and engineering. While we are interested in engineering design contexts, which might be different from other non-engineering contexts, these questions transcend most disciplinary boundaries. In design, there are always many alternative solutions, some of which await discovery and some of which may require additional knowledge for it to work. The choice of multiple criteria for evaluating each alternative, and the specific selection are decided in a team process comprising of participants from diverse disciplines including those that are non-technical. Over the last 20 years, there have been many studies done on selection among alternatives in design. These studies have been reported in a variety of journals including Research in Engineering Design; they form a web from which part is depicted in Fig. 1. The web reflects the relations between them: some studies rely on other study results (stated ‘‘positive reference’’ in the legend); they criticize previous studies (stated ‘‘negative reference’’) and they propose improvements to other proposals (thereby describing their limitations, also considered negative); or they merely report what another study stated (‘‘indifferent reference’’). It is difficult to go through these studies and synthesize a coherent position as they have been conducted by authors from different disciplines, having different beliefs, and often critical of each other. The studies at the top of the figure represent the pool of methods and theoretical work that form the basis of subsequent work. Some of these studies are based on theoretical frameworks, e.g., Sen and Arrow (both from public choice theory) and Keeny and Raiffa (from multi-attribute decision theory); some are based on a theoretical framework with strong influence from practice, e.g., Saaty and Suh, and others originated in practice, e.g., QFD and Pugh. These origins are important because they form a context that permeates the discussion on the questions regarding methods I raised before. For example, consider a subset of these studies (Fig. 2), Arrows impossibility theorem (AIT) [Ar63], constructed in the context of public choice by voting, forms the basis of Hazelrigg’s (1996a, b, 1997, 1998, 1999) contention that