Definition
The Burden of Proof (Onus Probandi) is the obligation of a party in a dispute to provide sufficient evidence for their claim. In logic and science, the burden of proof always lies with the person making the positive assertion, particularly if that assertion is extraordinary or contradicts established knowledge.
Why It Matters
The burden of proof is the ‘firewall’ of rational discourse; without it, we would be paralyzed by an infinite number of unfalsifiable claims, making it impossible to distinguish between meaningful data and noise.
Core Concepts
- Positive Assertion: If Person A claims “God exists” and Person B says “I don’t believe you,” the burden of proof is on Person A. Person B does not have to “prove” that God doesn’t exist.
- Extraordinary Claims: As Carl Sagan famously stated, “Extraordinary claims require extraordinary evidence.” The more a claim deviates from current scientific understanding, the higher the standard of proof required.
- Shifting the Burden: A common logical fallacy where a person making a claim demands that their opponent disprove it (e.g., “You can’t prove that aliens haven’t visited Earth, therefore my claim is valid”). This is a violation of rational discourse.
- Legal Standard: In criminal law, the burden of proof lies with the prosecution (presumption of innocence) and must meet the standard of “beyond a reasonable doubt.” In civil law, the standard is usually “preponderance of evidence.”