Evidence based-policy (EBP) is a popular research paradigm in the applied social sciences and within government agencies. Informally, EBP represents an explicit commitment to applying scientific methods to public affairs, in contrast to ideologically-driven or merely intuitive “common-sense” approaches to public policy. More specifically, the EBP paradigm places great weight on the results of experimental research designs, especially randomised controlled trials (RCTs), and systematic literature reviews that place evidential weight on experimental results. One hope is that such research designs and (...) approaches to analysing the scientific literature are sufficiently robust that they can settle what really ‘works’ in public policy. Can EBP succeed in displacing reliance on domain-specific expertise? On our account, this is seldom, if ever, the case. The key reason for this is that underlying this approach is generally an appeal to argument by induction, which always requires further assumptions to underwrite its validity, and if not induction, some other argument form that also requires assumptions that are very often not validated for the case at hand. (shrink)