Full Idea
Stoics say the study of syllogisms is extremely useful; for it indicates what is demonstrative, and this makes a big contribution toward correcting one's opinions; and orderliness and good memory indicate attentive comprehension.
Gist of Idea
Stoics like syllogisms, for showing what is demonstrative, which corrects opinions
Source
report of Stoic school (fragments/reports [c.200 BCE]) by Diogenes Laertius - Lives of Eminent Philosophers 07.45
Book Reference
'The Stoics Reader', ed/tr. Inwood,B/Gerson,L.P. [Hackett 2008], p.11
A Reaction
The stoics also developed propositional logic. The main point is that they liked formal logic, which is not true of all the ancient schools.