Claim detection is the NLP task of identifying factual assertions or claims in text that can be verified as true or false. It is the first step in the automated fact-checking pipeline — before you can check whether something is true, you must first identify what statements are even making factual claims.

What Counts as a Claim

• Factual Claim: "The Earth's average temperature has risen 1.1°C since pre-industrial times." — A verifiable statement about the world.
• NOT a Claim: "I think chocolate ice cream is the best." — An opinion, not objectively verifiable.
• NOT a Claim: "Good morning!" — A greeting with no factual content.
• Borderline: "This is the most important election of our lifetime." — Contains both opinion and an implicit factual claim.

Check-Worthy Claim Detection

• Not all claims are worth checking. "The sky is blue" is a claim but trivially true.
• Check-worthiness identifies claims that are important, contested, or potentially misleading — statements whose truth or falsehood matters to public discourse.
• Politicians' statements, health claims, and viral social media posts are high-priority for check-worthiness.

Detection Methods

• Rule-Based: Identify sentences containing numbers, statistics, named entities, and comparative language — these are more likely to contain claims.
• Classification Models: Fine-tune BERT/RoBERTa to classify sentences as claim vs. non-claim, check-worthy vs. not check-worthy.
• Sequence Labeling: Tag claim spans within longer text — a paragraph may contain multiple claims mixed with commentary.
• LLM-Based: Prompt GPT-4 or similar models to extract claims from text and assess check-worthiness.

The Fact-Checking Pipeline

1. Claim Detection → Identify what factual claims are being made. 2. Evidence Retrieval → Find relevant evidence from trusted sources. 3. Verdict Prediction → Determine if the claim is supported, refuted, or unverifiable.

Tools and Systems

• ClaimBuster: System that scores sentences for check-worthiness.
• Google Fact Check Tools: API and markup for fact-check articles.
• Full Fact: UK fact-checking organization developing automated tools.

Claim detection is the critical first step in combating misinformation — you can't check facts you haven't identified as claims.