Argument from opposites

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

Both the subjects and the predicates are different, so the argument form is gamma (a is X because b is Y): “Peace (a) can be started by truth (X) because wars (b) can be started by lies (Y)”.

The relationship between the subjects is identical to that between the predicates, so the substance is ‘i’.

The argument lever describes the semantic relationship between the subjects a and b and the predicates Y and X. It can thus be formulated as “Wars (b) is OPPOSITE to peace (a) and can be started by lies (Y) is OPPOSITE to can be started by truth (X)”.

Other examples

• But since, old man, false statements are persuasive among mortals, you should believe the opposite too: That many truths turn out to be incredible to mortals (this example is mentioned by Aristotle in his description of the topos ‘from opposites’ in Rhetorica 1397a and is taken from Euripides, Thyestes, fragment 396 – translation and info from G.A. Kennedy (1991), Aristotle, On rhetoric: A theory of civic discourse (p. 191). New York / Oxford: Oxford University Press).
• Self-control is good because a bad temper is bad.

Notes

The example is based on a quote by Julian Assange.