, Volume 33, Issue 2, pp 339–360 | Cite as

Mechanisms and the Evidence Hierarchy

  • Brendan Clarke
  • Donald Gillies
  • Phyllis Illari
  • Federica Russo
  • Jon Williamson


Evidence-based medicine (EBM) makes use of explicit procedures for grading evidence for causal claims. Normally, these procedures categorise evidence of correlation produced by statistical trials as better evidence for a causal claim than evidence of mechanisms produced by other methods. We argue, in contrast, that evidence of mechanisms needs to be viewed as complementary to, rather than inferior to, evidence of correlation. In this paper we first set out the case for treating evidence of mechanisms alongside evidence of correlation in explicit protocols for evaluating evidence. Next we provide case studies which exemplify the ways in which evidence of mechanisms complements evidence of correlation in practice. Finally, we put forward some general considerations as to how the two sorts of evidence can be more closely integrated by EBM.


Mechanism Difference-making Evidence Evidence of mechanism Evidence in medicine Evidence-based medicine 



We thank the UK Arts and Humanities Research Council for supporting this research. F. Russo also acknowledges financial support from the FWO-Flanders (2012–2013) as Pegasus Marie Curie Fellow. We are extremely grateful to the very many people who came to various events we organised during 2012, and participated in the discussions that allowed us to develop these ideas. We owe particular thanks to Ian McKay, Barbara Osimani, Jacob Stegenga and David Teira for extensive comments leading to significant improvements to the paper.


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Brendan Clarke
    • 1
  • Donald Gillies
    • 1
  • Phyllis Illari
    • 1
  • Federica Russo
    • 2
  • Jon Williamson
    • 3
  1. 1.Science and Technology StudiesUniversity College LondonLondonUK
  2. 2.Dipartimento di Studi UmanisticiUniversità degli Studi di FerraraFerraraItaly
  3. 3.Philosophy, SECLUniversity of KentCanterburyUK

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