Passage Summary: A cereal company says their health claims are true because healthy people buy the cereal. They then say they know these people are healthy because they only buy cereal with true health claims.

Conclusion: The health claims on the cereal package are true.

Reasoning: Health-conscious consumers buy the cereal, and they only buy cereal if the claims are true; we know these consumers are health-conscious because they only buy cereal with accurate health information.

Analysis: This is a classic case of circular reasoning, where the evidence for the conclusion already assumes the conclusion is true. The author uses the "truth of the claims" to define the "health-consciousness of the consumers," then uses those "health-conscious consumers" to prove the "truth of the claims." When looking for a parallel, seek out an argument that chases its own tail by using two statements to prove each other. It's like saying "I am a great leader because my followers are smart, and I know they are smart because they chose me as their leader."