## 2 Competing Theoretical Perspectives on Sustainability and Sustainable Development  
One way to illustrate how sustainability and sustainable development are contested phenomena is to pinpoint some of the many disputes over their meaning represented in the scholarly literature that displays a multitude of co-existing definitions based in particular values and ideological orientations [6; 7]. There are, for instance, disagreements over which theory of justice [28; 29; 30; 31; 32; 33] and, more generally, which moral theory, should underpin sustainability and sustainable development [7; 34]. Moreover, several ways to define and measure sustainability and sustainable development have been proposed, reflecting different normative and ideological positions, e.g., [6; 7; 19; 35; 36]. No matter how straightforward and objective the'solutions' to unsustainability may seem to be, they are inescapably political in the sense that they always rest on particular values and ideologies and promote certain interests. In this section, we illustrate these political circumstances with a brief overview of two main positions on sustainability in the scholarly literature: the production and consumption perspectives [37]. The former perspective exemplifies 'weak' versions of sustainability and sustainable development, whereas the latter provides examples of'strong' versions. This is by no means a comprehensive overview of these positions, even less so of the disagreements concerning sustainability and sustainable development generally. Our overview serves to illustrate a few major controversies between proponents of these two perspectives and, thus, to provide concrete examples of how sustainability and the process to attain it are disputed. The choice to focus on the production and consumption perspectives stems from the circumstance that they represent two significantly different perspectives that, moreover, are common in policies for sustainable public procurement. One reason for this is that these perspectives are closely associated with different political economy approaches to sustainability [18; 19; 38]. Since public procurement is largely founded on economic theory, disputes over economic approaches are highly relevant to its practice. Another reason is that both perspectives have been highlighted as important by civil servants in at least one member state, Sweden [19], where both perspectives also surface in public procurement policies [18]. It needs to be clarified, however, that the analytical strategy of this paper is more empirically driven, in that we identified the problem representations implied in the identified guidelines and best practice exemplars (as detailed in the methodology section). The production perspective entails a focus on promoting sustainability by facilitating innovative production, while the consumption perspective is centered on changing unsustainable consumption patterns, and the power relations and inequalities associated with these. Production perspective approaches to sustainability are underpinned by the assumption that technological innovations are the primary drivers of sustainable development. Conversely, the consumption perspective stresses that political interventions are needed in order to limit consumption in ways that transform economic and social relations, as well as their environmental impacts [37]. The primary solutions to the unsustainable predicament from a production perspective are centered on environmental reforms of current modes of production. These reforms are to create conditions that incite sustainable technological innovations, which enable a perpetual and sustainable economic growth. Consequently, economic, social and ecological sustainability can be achieved without a fundamental transformation of current socio-ecological relations. This perspective is indicative of approaches to sustainability that, in the research literature, are labeled market environmentalism [20; 21; 22] and are based in neoclassical economics [39].