Antitheton
An argument built on opposition — the reasoning counterpart to the figure of antithesis.
Antitheton names a proof constructed from contraries: if the opposite case leads to an unacceptable result, the case at hand is supported. Classical rhetoricians distinguished it from antithesis, which is the stylistic balancing of opposed phrases.
The distinction is worth keeping. Antithesis is a shape a sentence takes; antitheton is a move an argument makes. A passage can have one without the other.
It underlies much practical persuasion: policy arguments from the cost of inaction, legal arguments from absurd consequences, and everyday reasoning that tests a claim by examining its negation.
Common mistake: false dichotomy. Antitheton is only as sound as the claim that the two options exhaust the possibilities; unstated third options are where the figure most often fails.
“If honesty were unprofitable, every merchant would already be ruined; they are not, so honesty pays.”
Keep reading the glossary
A grammatical balance of two opposed ideas — 'to be or not to be'.
A compressed syllogism in which one premise is left unstated, to be supplied by the audience.
Balancing a statement by adding the qualifying other side — 'not only... but also'.
Pairing a promise with a threat, or a reward with a penalty, in balanced form.