Almost two decades ago, Peter M. Haas formulated the epistemic communities framework as a means of exploring the influence of knowledge-based experts in international policymaking. Specifically, the approach was designed to address decision-making instances characterized by technical complexity and uncertainty. Control over the production of knowledge and information enables epistemic communities to articulate cause and effect relationships and so frame issues for collective debate. Remarkably however, we still know very little about the variety of ways in which decision-makers actually learn from epistemic communities. This article suggests that variety is best captured by differentiating between the control enjoyed by decision-makers and epistemic communities over the production of substantive knowledge -or means -that informs policy on the one hand and the policy objectives -or ends -to which that knowledge is directed on the other. The implications of this distinction for the types of epistemic community-decision-maker learning exchanges that prevail are elaborated using a typology of adult learning from the education literature which delineates the four possible learning situations. Section one of the article examines how the epistemic communities' framework currently organizes and captures variation in decisionmaker learning, outlines a possible learning typology and addresses the likely criticisms of this enterprise. The potential usefulness of this typology requires empirical investigation; section two of the article uses the comparative study of US and EU decision-makers' interaction with the epistemic community that formed around the regulation of the biotech milk yield enhancer bovine somatotrophin (rbST) to explore how the learning types identified in the model play out in practice. The third and concluding section examines how well the learning types measure up against three of the main desiderata for assessing such schema.KEYWORDS epistemic communities; knowledge production; policy learning; policy transfer; bovine somatotrophin (rbST); biotechnology.
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I TRODUCTIOThough the epistemic communities concept enjoys good currency across political science 1 , nearly two decades after it was first unveiled (Haas, 1990(Haas, , 1992a, the epistemic communities' framework continues to buck the academic trend of conceptual revision through empirical investigation observed in similar approaches (notably, the study of policy communities and the advocacy coalition framework). Despite the presence of a healthy empirical literature using the idea of an epistemic community in different ways and in conjunction with different approaches, only in a handful of studies have related any findings back to framework itself (Dunlop, 2000a;Radaelli, 1995;Zito, 2001). Significantly, none of these interventions address the central mechanism that underpins epistemic communities'influence -the ability to assume control over knowledge production and in doing so guide decision-maker learning.It is clear that epistemic commu...