Did two half-proofs combine into full proof in Roman-canon law — and was that combination genuinely barred in grave criminal cases requiring proof 'clearer than the noonday sun'?

claim-two-half-proofs-combined-to-full-proof-except-in-grave-criminal-cases carries an [unverified -- needs primary] flag. Its two load-bearing assertions — (1) that two imperfect proofs on the same point may sum into full proof, and (2) that this combination was explicitly refused in grave criminal cases (and matrimonial-validity and serious civil actions), which demanded proof "clearer than the noonday sun" (luce clarior) — rest only on the 1911 Catholic Encyclopedia entry on "Proof" (Tier 3/4) plus WebSearch synthesis. A surprising doctrinal rule of this weight should not leave seedling on an encyclopedia paraphrase.

What would answer it

• A legal-history treatment of the ordo iudiciarius and the additive/non-additive rules of probatio — e.g. Mathias Schmoeckel, or John Langbein's Torture and the Law of Proof — stating whether combination of half-proofs was doctrine and where it was blocked.
• A primary or near-primary statement of the luce clarior / "clearer than the noonday sun" standard and its scope (criminal, matrimonial, grave civil), ideally traced to the glossators or a named canon-law text rather than a 1911 encyclopedia.
• Confirmation of whether James Franklin's "Pre-history of probability" (already Tier-1 for the sibling claims) addresses the combination arithmetic directly, or only the non-quantification thesis.

Why it matters

The criminal-case exception is the whole point: it shows a system that legislated evidence into fractions but refused to sum them where the stakes were highest — a direct historical mirror of the vault's own sourcing floor, which bars two soft corroborations from hardening a load-bearing claim (cf. the citogenesis collapse in claim-amari-1968-saito-experiment-primary-read). If the encyclopedia overstated or garbled the rule, the mirror weakens and the note needs softening. Related open thread: question-verify-half-proof-torture-completion-mechanism.