Full Idea
Stoics reduced universals to thoughts or concepts, ...so in order to make universal statements which would not conflict with their metaphysics, they rephrased sentences of the form 'Man is...' as conditionals: 'If something is a man, then it is...'
Gist of Idea
Stoics avoided universals by paraphrasing 'Man is...' as 'If something is a man, then it is...'
Source
report of Stoic school (fragments/reports [c.200 BCE]) by A.A. Long - Hellenistic Philosophy 4.3.3
Book Reference
Long,A.A.: 'Hellenistic Philosophy' [Duckworth 1986], p.141
A Reaction
[reference to Sextus, Adv Math 9.8] Predicate logic handles this with ease. It is something like the strategy of Ramsey sentences, for eliminating metaphysical properties.