Informally fallacious argument

Informally fallacious argument: An argument with a false premise or methodological flaw. Circular arguments are informally defective but formally valid.

Source: ‘What is Good? What is Bad? The Value of All Values across Time, Place and Theories’ by John McMurtry, Philosophy and World Problems, Volume I-III, UNESCO in partnership with Encyclopedia of Life Support Systems: Oxford, 2004-11.