"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.