Full Idea
Dialectic itself is necessary, and is a virtue which contains other virtues.
Gist of Idea
Dialectic is a virtue which contains other virtues
Source
report of Stoic school (fragments/reports [c.200 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 07.46
Book Reference
'The Stoics Reader', ed/tr. Inwood,B/Gerson,L.P. [Hackett 2008], p.12
A Reaction
Presumable the virtues which are 'contained' are the whole panoply of other intellectual virtues. These will be virtues of intellectual character (Zagzebski), not virtues of processes (Sosa).
Related Idea
Idea 20776 Dialectics is mastery of question and answer form [Stoic school, by Diog. Laertius]