You know what we absolutely love? When an author spells out the theme for you in a simple, easily digestible sentence. Take Asimov's stance on violence in Foundation. Salvor Hardin says, "Violence is the last refuge of the incompetent" (III.1.55). Boom. Done. Any character that prefers a quick, simplistic, and violent solution to a problem does not fare well in Asimov's universe. Enter characters like Hardin, who prefer to think their way to nonviolent solutions: they're the heroes of day. And we here at Shmoop find the notion very appealing.
Foundation is ultimately a novel about achieving pacifism through science and rationalism.
As the stories progress, violence becomes a more acceptable option.