Species of Abductive Reasoning in Fact Investigation in Law

Imaginative reasoning is as vital in law as it is in any other discipline. During fact investigation, hypotheses, in the form of possible charges or complaints, must be generated or discovered, as well as evidence bearing on these hypotheses. During the later process of proof, arguments in defense of the relevance, credibility, and probative force of offered evidence on hypotheses must also be generated. In no context known to me are hypotheses, evidence, and arguments linking them supplied at the outset for investigators and attorneys. These ingredients must be generated by imaginative or creative thinking. How we are able to generate new ideas has been an object of study for millennia. In spite of this, our imaginative and creative reasoning abilities are not well understood. There is considerable debate about the forms of reasoning that take place as we generate new ideas and evidential tests of them. This Article concerns a form of reasoning called “abduction,” which was suggested over a century ago by the American philosopher Charles S. Peirce as a reasoning mechanism underlying imaginative and creative thought. Most of us hear about two forms of reasoning: (1) deduction, showing that something is necessarily true, and (2) induction,showing that something is probably true. There is reason to believe that new ideas, in the form of hypotheses, may not be generated by induction or deduction. In this Article I will suggest that there are several species of abductive reasoning by which we show that something is possibly or plausibly true. I relate these species of abduction to intellectual tasks performed by investigators during fact investigation and to those performed by advocates during the process of proof. Consideration of these species of abductive reasoning exposes the richness of this important discovery-related activity.