What is the role of ethics in The Chrysalids?

There are several ethical systems in the Chrysalids. The people in Waknuk and the surrounding communities have an ethical system that seems to be based on post-apocalyptic survival, which for the most part works as a survival strategy, but doesn't work really well to help them develop morally or spiritually. They confuse that kind of survival with religion... and maybe they had to believe in it that much to survive, but now the extremism that led to their survival seems overbearing and way too harsh... at least to the soft society reading the novel. :)

The telepaths have a loyalty based on the intimacy of knowing each other's minds. They are incapable of betraying each other without severe mental (and spiritual?) consequences, and so they will not, even for survival. Uncle Axel saves them from this decision.

The fringe people, formerly of waknuk, have a more broken system. They are about survival as well, but don't have the means without raiding or harming others, and so they do.

The Zealanders who have a large telepath population don't seem to have any ethics at all other than survival of the fittest... and they of course feel that telepaths are that. They have no compunction about murdering the non-telepaths. Theoretically at least, this is the ethical system that David and his friends will learn to embrace.