Perhaps the parsing of “reasonable doubt” vs. “preponderance of evidence” is a Talmudic exercise. The Hardest Working Man in Show Business, Richard Posner, in his review of The Origins of Reasonable Doubt: Theological Roots of the Criminal Trial, writes:
James Whitman, a legal historian at Yale Law School, claims in his new book that the reasonable-doubt rule is unrelated, in its historical origins and in its present-day usage, to any concern with accuracy in the determination of guilt, or even to the protection of the innocent. The concept of reasonable doubt, he argues, is designed solely to make judges and jurors comfortable with convicting people. It is a vestige of a vanished era in which “moral comfort” was important to people involved in the criminal justice system. Whitman wants the United States to jettison the rule, along with the rest of the Anglo-American (common law) apparatus of criminal justice, and adopt the criminal justice system of continental Europe instead.