Paraphrasing from Plato's The Republic, when the rulers and their auxillaries raise children with proper balance in the body and soul, there will be no need to deliberate on what is the right legislation, for the legislators themselves will be just in their duties.
In the end of the day, we need proper education, not only in technical excellence, but also societal awareness, what it means to be good and how to uphold oneself to such a standard even if everyone around them does not. This is how you defend against the men with guns.
"To rear a child and give him an education is easy, but to put a good mind into him is impossible... By teaching you will never make the bad man good."
— Theognis of Megara (Elegies, lines 429–438) (quoted by both Plato in Meno and Aristotle in Nicomachean Ethics)
Or:
"Naturam expellas furca, tamen usque recurret."
("You may drive out Nature with a pitchfork, yet she will always return.") — Epistles, Book I
More generally, in a system of agents, you could impose deep structure by construction on all the agents, or figure out from a set of black box agents, necessary convergence principles. Or you could treat them as black boxes, but instead of arguing intrinsically, impose external controls on the system to bound the error.
Probably a lot of ways to think about it, but when you phrase it this way, it becomes quickly pretty hard!
In the end of the day, we need proper education, not only in technical excellence, but also societal awareness, what it means to be good and how to uphold oneself to such a standard even if everyone around them does not. This is how you defend against the men with guns.