Definition:Invalid Argument/Also known as

Invalid Argument: Also known as

An invalid argument is also known as a fallacy.

Some authors use the term unsound argument to mean invalid argument.

However, because of the confusion about the meaning of sound argument, which can be used to mean either valid argument or proof, it is recommended that this term not be used.

Sources

• 1965: E.J. Lemmon: Beginning Logic ... (previous) ... (next): Chapter $1$: The Propositional Calculus $1$: $1$ The Nature of Logic