Definition
Plain language
An assertion that depends on the specific data shown — like 'this method always works,' which one counterexample can disprove.
Why it matters: Distinguishing claims that are specifically refutable from broader generalizations is essential for reading papers honestly and designing experiments that can fail.
For example, 'this model achieves 95% accuracy on the test set' is a hard claim — one rerun showing 80% would falsify it.