Relative plausibility redux (review of Allen and Pardo, part 2)

As we mentioned in a previous post, law professors Ron Allen and Mike Pardo summarize and critique probabilistic theories of evidence on pp. 7-12 of their most recent paper “Relative plausibility and its critics.” (Hold on: “critique” is too polite. They launched a blistering attack!) In addition, they also present an attractive and intuitive alternative theory of legal trials in their paper. Without further ado, here is how they describe their theory of  “relative plausibility” in their own words (pp. 13-14, footnotes omitted):

“Rather than characterizing proof standards as probabilistic thresholds (such as 0.5), [our theory of] relative plausibility accounts for the standards in terms of explanatory thresholds. The proof process involves two stages: (1) the generation of potential explanations of the evidence and events, and (2) a comparisons of the [plaintiff’s and defendant’s competing] explanations in light of the applicable standard of proof. In general, the process depends on the parties to obtain evidence and to offer what they consider to be the best explanation (or explanations) that support their respective cases. *** The explanatory thresholds vary depending on the standard—with higher standards requiring a higher threshold. Under the ‘preponderance of the evidence’ standard, fact-finders determine whether the best of the available explanations favors the plaintiff or the defendant. The best available explanation will favor the plaintiff if it includes all of the legal elements of plaintiff’s claim; it will favor the defendant when it fails to include one of more elements. A number of general criteria affect the strength or quality of an explanation. These criteria include considerations such as consistency, coherence, fit with background knowledge, simplicity, absence of gaps, and the number of unlikely assumptions that need to be made.”

This relative plausibility theory of legal proof is itself very plausible and intuitive. Alas, this theory does not banish the specter of probability from the trial process, for the word “best” is just code for “more probable”, whether we assign a numerical value or not to describe the level of a story’s plausibility! (See image below, by way of example.) Stay tuned, we will weigh the pros and cons of Allen and Pardo’s relative plausibility theory in our next two blog posts …

Related image
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One Response to Relative plausibility redux (review of Allen and Pardo, part 2)

  1. Pingback: In defense of relative plausibility (review of Allen and Pardo, part 3) | prior probability

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