Words / C2

f-uh-LAYSH-uh-s/fəˈleɪʃəs/

Fallacious means based on a mistaken belief, or logically unsound: a fallacious argument, fallacious reasoning. False is everyday; fallacy (already in the dictionary) is the noun. Fallible (this batch) is “able to err” — a cousin, not a synonym. Do not call a rounding error fallacious as if it were a trick of logic.

Meaning

Based on a mistaken belief; logically unsound (formal).

Examples

• “A fallacious leap from one anecdote to “the cohort” failed review.”
• “False is everyday. A fallacy is the named error (already in the dictionary). Facetious (already in the dictionary) is joking at the wrong time — a lookalike. An honest miscount is an error, not a fallacious syllogism.”

Good to know

Logically false; based on a fallacy. Everyday: false. Noun: fallacy. Cousin: fallible (can err). Mix-up: facetious. A slip is not a fallacy until it argues.

Near in meaning

false

New