Evidential reasoning in law

Legal fact-finding as a model for uncertain evidential reasoning and decision-making.

My initial motivation for studying fact-finders' (judges' and jurors') reasoning with evidence lies in the working hypothesis that the task of fact-finders in criminal trials can serve as a model for evidential reasoning and decision-making under uncertainty more generally. This working hypothesis has proven fruitful in my recent work, both epistemological and psychological.

From an epistemological perspective, and at a very abstract level (ie independent from any consideration of real procedures within a particular judicial system), the figure of the fact-finder is useful as it exemplifies uncertain, evidential reasoning preceding (high-stake) decision-making while allowing for clear delineation of the evidential set, the factual questions to be solved, and the stakes (and utilities) of the decision. Furthermore, the common law notion of 'standard of proof' allows for a clear distinction between factual conclusions, probability assessment, threshold for acceptance and decision. This is one reason why I have taken this model to study more generally the notion of reasonable doubt (see Vorms & Hahn 2019). Lastly, when it comes to the study of the epistemic status of testimony, I show in a working paper (Vorms in preparation) that consideration of courtroom witness evidence enables us to show how the pragmatic aspects of everyday conversation take on a particular significance when it comes to informing decisions.

Further, these interesting features of the figure of the juror are at the basis of a whole experimental paradigm in the psychology of reasoning, and the experimental study of judgement and decision-making, to which I have been trained during my Marie-Sklodowska Curie fellowship in the psychology department at Birkbeck college, London. Some of my ongoing experimental projects belong to this line of research.

A comparative, epistemological study of legal rules of evidence

But my study of evidential reasoning in legal contexts has also led me to get interested in the reality of legal evidential rules and proceedings. After my Marie Curie fellowship in the UK, where I could acquire some knowledge of common law criminal evidential rules, I launched an interdisciplinary research group with legal scholars and philosophers of science, aimed at studying French judges' evidential reasoning (mostly through analysis of written decisions), which obtained funding by the University of Grenobles (through an IRS - Strategic research initiatives - project called Raiso-Preuve). Together, we built a training course in evidential reasoning, which we delivered to students of the École nationale de la magistrature (French national judges' training institute). These interdisciplinary exchanges made me realise how different the common law and French conception of evidence were, and I decided to complete a Master 2 degree in French law. My master thesis, which can be downloaded here (and here the extended synopsis in English of the book I'm drawing from it) proposes a critical study of French law of evidence from an epistemological and comparative perspective. 

This work earned me the recognition of French legal scholars, who invited me to give talks and write articles in legal journals about what 'judicial truth' means, the very French notion of 'innermost conviction' (intime conviction), and the presumption of innocence (see talks and publications lists). An entire workshop at University of Rennes was dedicated to my research on judges' evidential reasoning, and was followed by a published interview.

A monograph, whose extended synopsis in English can be downloaded here, will be published by the Éditions du Seuil.