Proof, doubt and the fear of miscarriages of justice are at the heart of the popular imagery of trials, which features judges and juries trying to assemble the pieces of a veritable jigsaw puzzle to arrive at the truth. Finding the facts before any legal qualification seems paramount since a decision based on factual errors cannot be right. However, the way in which judges must form their opinions on questions of fact is a topic remarkably absent from French law (both positive law and legal scholarship). A blind spot in the law, judges' reasoning on facts and evidence has not been the subject of in-depth epistemological analysis either. Although the norms of correct reasoning are a privileged subject for philosophy, they are generally studi...