Valuing reasons: Analogy and epistemic deference in legal argument

This thesis addresses two enduring issues in legal theory-- rationality and its association with rule of law values--by offering detailed models of two patterns of legal reasoning. One is reasoning by analogy. The other is the inference process that legal reasoners (as practical reasoners) use when they defer epistemically to scientific experts (theoretical reasoners) in the course of reaching legal decisions. Discussions in both chapters reveal that the inference pattern known as "abduction" is a deeply important element of many legal inferences, including analogy and epistemic deference to experts--something that has been largely unrecognized in legal theory. After presenting a detailed model of analogy, Chapter 1 argues that legal reasoning by analogy, like analogical argument in logic, mathematics, and the natural sciences, possesses a great deal of rational force when properly executed. Chapter 2 investigates the reasoning process by which non-expert legal reasoners (judges and juries) defer epistemically to the judgments of scientists. It presents five main conclusions or explanations. (i) Every practical syllogism actually consists of two distinct chains of inference, and what is usually considered in writings on practical reasoning to be the minor premise of a practical syllogism is actually the conclusion of a separate chain of argument. (ii) When a practical reasoner defers epistemically to a theoretical expert, this separate chain of argument has a special structure, which is modeled in Chapter 2. (iii) The non-expert legal reasoner must always make a prescriptive practical judgment about the standard of epistemic appraisal and level of epistemic confidence that the reasoner requires of scientific evidence before it may be relied upon in reaching a legal decision. (iv) Legal systems should be (and some are) committed to an emergent rule of law ideal identified and referred to as "intellectual due process" which condemns epistemically arbitrary reasoning processes insofar as they play a role in legal decisionmaking. (v) Since non-arbitrariness is a necessary condition of both epistemic and legal legitimacy, we have compelling reason to doubt that the non-arbitrariness condition can be met when non-experts defer epistemically to scientific experts.