QUESTIONS OF EVIDENCE IN EVIDENCE-BASED POLICY

Evidence-based approaches to policy making are growing in popularity. A generally embraced view is that with appropriate evidence at hand decision and policy making will be optimal, legitimate and publicly accountable. In practice, however, evidence based policy making is constrained by a variety of problems concerning the very concept of evidence. Some of these problems are explored in this article, in the context of the debates on what counts as evidence and how to use it, from which they originate. It is argued that the source of much disagreement might be a failure to addressing crucial philosophical assumptions which inform, often tacitly, these debates. Three controversial questions are raised which appear central to some of the challenges faced at present by evidence-based policy making: firstly, how do certain facts candidate themselves as evidence; secondly, how can be decided what evidence we have, and how much of it; thirdly, how can we combine different types of evidence. By exploring these questions it is shown how, against common wisdom, informing the discussion on evidence based policy by philosophical analysis proves instrumental (and indeed useful) to claryfying and settling difficulties in practice.