The Flat Earth movement raises a deeper question than geography: how do people decide what counts as scientific truth? This debate examines whether Flat Earth claims meaningfully challenge mainstream science through testable hypotheses, falsifiability, and reproducible evidence—or whether they reflect cognitive biases, algorithm-driven misinformation, and declining trust in scientific institutions. What role do peer review, empirical measurement, and consensus play in validating knowledge? And when individuals reject centuries of observational data, is science failing to communicate—or is skepticism being confused with denial?