Types of learning and varieties of innovation: how does policy learning enable policy innovation?

Policy innovation is considered important for addressing major challenges such as climate change and the sustainable energy transition. Although policy learning is likely to play a key role in enabling policy innovation, the link between them remains unclear despite much research on both topics. To address this gap, we move beyond a binary treatment of policy innovation and differentiate policy problem innovation from policy instrument innovation and policy process innovation. Subsequently, we synthesise the literature on policy learning with the research on the multiple streams framework (MSF), a well-known lens for explaining policy innovation. Like earlier policy learning studies, we distinguish several types of learning by posing the key questions of learning, but in the context of each stream of the MSF: who learns (actors), what (beliefs), how (modes), and to what effect (ripening). This new conceptualisation clarifies the relationship of each type of policy learning to the varieties of policy innovation. Further, it indicates that policy learning is likely to result in policy innovation if and only if it influences the coupling among the three streams during a window of opportunity - through policy entrepreneurship - and not otherwise. We conclude with the implications of this study for future research on policy innovation, policy learning, and the MSF.