fallacy; fallacious argument
Formal, academic term for a mistaken belief or logically unsound argument. Often used in philosophical or critical contexts.
That claim is based on an obvious fallacy.
His paper refutes a common fallacious argument.
The kanji 謬 (mistake, error) and 説 (theory, explanation) combine to mean 'erroneous theory'. The exact historical derivation is uncertain; the term is used in modern formal writing.