Proving Causation: The Holism of Warrant and the Atomism of Daubert
Journal of Health and Biomedical Law, Vol. 4, pp. 253-289, 2008
38 Pages Posted: 12 Jan 2009 Last revised: 27 May 2014
In many toxic-tort cases - notably in Oxendine v. Merrell Dow Pharmaceuticals, Inc, and in Joiner v. G.E., - plaintiffs argue that the expert testimony they wish to present, though no part of it is sufficient by itself to establish causation by a preponderance of the evidence, is jointly sufficient to meet this standard of proof; and defendants sometimes argue in response that it is a mistake to imagine that a collection of pieces of weak evidence can be any stronger than its individual components. This article draws on the epistemological theory I first presented in 1993 in Evidence and Inquiry, and then amplified and refined in 2003 in Defending Science - Within Reason. This theory of evidence shows that, under certain conditions, a combination of pieces of evidence none of which is sufficient by itself really can warrant a casual conclusion to a higher degree than any of its components alone.
When my account is applied to the very complex congeries of evidence typically proffered to prove general causation in these toxic-tort cases, it improves on the influential Bradford Hill criteria for assessing causation; and it suggests answers to questions frequently raised in such cases: e.g., whether epidemiological evidence is essential for proof of causation, and whether such evidence should be excluded if it is not statistically significant. Moreover, the argument of this paper reveals that by obliging courts to screen each item of expert testimony individually for reliability, the atomism implicit in Daubert will sometimes stand in the way of an accurate assessment of the worth of complex causation evidence.
Keywords: toxic torts, causation evidence, admissibility, preponderance, Weight of Evidence methodology, Bradford Hill criteria, evidentiary atomism, Daubert v. Merrell Dow Pharms., Inc.
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