Full Idea
Stoics say man differs from irrational animals because of internal speech ...and in virtue of impressions created by inference and combination. Because of this man grasps 'signal', of the form 'If this, then that', which follows from the nature of man.
Gist of Idea
Man is distinguished by knowing conditional truths, because impressions are connected
Source
report of Stoic school (fragments/reports [c.200 BCE]) by A.A. Long - Hellenistic Philosophy 4.3.1
Book Reference
Long,A.A.: 'Hellenistic Philosophy' [Duckworth 1986], p.125
A Reaction
[In Sextus, Adv.Math 8.275-] This is unusual. The distinctive feature of humans is their ability to assert conditionals (because they see connections - or associations - among their impressions). Nice thought.