Full Idea
Chrysippus argues against the 'swerve' of the Epicureans, on the grounds that they are doing violence to nature by positing something which is uncaused, and cites dice or scales, which can't settle differently without some cause or difference.
Gist of Idea
A swerve in the atoms would be unnatural, like scales settling differently for no reason
Source
report of Chrysippus (fragments/reports [c.240 BCE]) by Plutarch - 70: Stoic Self-contradictions 1045c
Book Reference
'The Stoics Reader', ed/tr. Inwood,B/Gerson,L.P. [Hackett 2008], p.103
A Reaction
That is, the principle of sufficient reason (or of everything having a cause) is derived from observation, not a priori understanding. Pace Leibniz. As in modern discussion, free will or the swerve only occur in our minds, and not elsewhere.
Related Ideas
Idea 5709 The actions of the mind are not determinate and passive, because atoms can swerve [Lucretius]
Idea 20834 Chrysippus allows evil to say it is fated, or even that it is rational and natural [Plutarch on Chrysippus]