Argument from opposites

You support a claim by stating its mirror image. The argument works because the support talks about the opposite thing and says the opposite of it, and the two oppositions line up: if lies start wars, truth starts peace. It can be attacked by showing that one of the pairs is not a true opposition, or that the two oppositions do not run parallel.

Example

Peace can be started by truth because wars can be started by lies

Standardised form

Peace (a) can be started by truth (X) because wars (b) can be started by lies (Y).

Transformations applied: none — the example is already in canonical form.

Classification

Both the subjects and the predicates differ, so the argument form is gamma (a is X because b is Y).

The relation between the subjects “peace” and “wars” is the same as the relation between the predicates “can be started by truth” and “can be started by lies”, so the argument substance is i.

The keyword OPPOSITE describes the relation that the subjects and the predicates both instantiate. The argument lever can thus be formulated as “Wars (b) is the OPPOSITE of peace (a), as being started by lies (Y) is the OPPOSITE of being started by truth (X)”.

Not to be confused with

• Argument from synonyms — The matching relation is sameness of meaning. SYNONYMOUS
• Argument from derivatives — One term is formed from the other. DERIVATIVE
• Argument from integratives — The relation is part to whole. INTEGRATIVE
• Non sequitur — Substance, not lever: the two relations do not match, so no lever can be formulated. d

Source

The example is based on a quotation by Julian Assange.

Other examples

• “False statements (b) are persuasive among mortals (Y), … many truths (a) turn out to be incredible to mortals (X).” — mentioned by Aristotle in his description of the topos “from opposites”, Rhetorica 1397a; taken from Euripides, Thyestes, fragment 396. Translation and information from G.A. Kennedy (1991), Aristotle, On Rhetoric: A Theory of Civic Discourse, p. 191. New York/Oxford: Oxford University Press.
• “Self-control (a) is good (X) because a bad temper (b) is bad (Y).” — source not yet recorded.