21st October 2019

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# What is the difference between tautology and contradiction?

"All is lost but there is hope." A compound statement is a tautology if its truth value is always T, regardless of the truth values of its variables. It is a contradiction if its truth value is always F, regardless of the truth values of its variables.

Just so, what is a tautology in logic?

In logic, a tautology (from the Greek word ταυτολογία) is a formula or assertion that is true in every possible interpretation. Philosopher Ludwig Wittgenstein first applied the term to redundancies of propositional logic in 1921.

What is a contingency in truth tables?

A propositional form that is true in all rows of its truth table is a tautology. A propositional form that is false in all rows of its truth table is a contradiction. A propositional form that is true in at least one row of its truth table and false in at least one row of its truth table is a contingency.

Is a tautology a fallacy?

Tautology. Tautology in formal logic refers to a statement that must be true in every interpretation by its very construction. In rhetorical logic, it is an argument that utilizes circular reasoning, which means that the conclusion is also its own premise.