QuoteOne thing that I do not understand though is whether, in Epicurus' time, there was such a thing as "social trust" among communities larger than say, the Garden, and whether this is thought to possibly contribute to a similar sense of security.
The Law of Xenia, or hospitality, was regarded as sacred to Zeus himself, and stories abound of the punishments inflicted on those who violated it. This unwritten law was the cornerstone of the Greek idea of social trust, and of the etiquette surrounding the host-guest relationship.
My favorite example of this kind of social trust is related by Vitruvius in his De Architectura:
QuoteIt is related of the Socratic philosopher Aristippus that, being shipwrecked and cast ashore on the coast of the Rhodians, he observed geometrical figures drawn thereon, and cried out to his companions: "Let us be of good cheer, for I see the traces of man." With that he made for the city of Rhodes, and went straight to the gymnasium. There he fell to discussing philosophical subjects, and presents were bestowed upon him, so that he could not only fit himself out, but could also provide those who accompanied him with clothing and all other necessaries of life.
As soon as he saw the geometrical figures drawn in the sand, he knew he was near Greeks. He knew that he could trust that the Law of Xenia would be upheld, and that he and his shipmates would survive the ordeal.
Principle Doctrine 39 may be the most relevant text on this question:
Quote39. He who best knew how to meet fear of external foes made into one family all the creatures he could; and those he could not, he at any rate did not treat as aliens [ἀλλόφυλά]; and where he found even this impossible, he avoided all association, and, so far as was useful, kept them at a distance.