Category: Logic
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Significant Paradoxes: Epistemology and Probability
38 Hempel’s Raven Scientific hypotheses are usually universal claims—for example, “All ravens are black.” By standard logic that statement is equivalent to its contrapositive “All non-black things are non-ravens.” Hempel pointed out a tension between that equivalence and ordinary confirmation. A sighting of a black raven clearly supports the hypothesis, yet the contrapositive implies that…
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Significant Paradoxes: Formal Logic
1 The Liar A single sentence—“This statement is false”—defies binary truth assignment. If it is true, then what it asserts must obtain: the statement is false. Yet if it is false, its content is not the case, which makes it true. The oscillation exposes a basic flaw in applying ordinary two-valued semantics to self-referential assertions.…