Contemporary developed western economies are commonly referred to as “knowledge-based” economies, which compete through drawing on the innovative and creative capacities of their local populations. Economic policy-makers must invest in and conserve the social, cultural and public resources that underpin dynamic and disruptive competitive activities, namely technological innovation and entrepreneurship, which bring new ideas and products to market. But these resources defy orthodox forms of economic knowledge and quantification. Their trajectories and outcomes are intrinsically uncertain. The paper draws on interviews with experts who advise governments on innovation and competitiveness, to understand what expert strategies are used to deal with this epistemological problem. Such experts must project and retain epistemological authority, but without lapsing too far into quantitative, economistic and bureaucratic forms of reason. The paper identifies three ways in which knowledge of the future can be validated, but without disguising uncertainty: it can be presented as practically useful; as aesthetically appealing; and as hinting at some “ultimate” form of ontological knowledge.