On a certain level, this novel seems to extol the virtue of the military. All of the characters who we are supposed to respect do at some point come to the conclusion that all real men are military men, that it makes sense that one can only be a citizen after completing a term of service. Dubois believes this from the beginning. He drills the idea of the importance of civic duty, and of violence into his students during History and Moral Philosophy: "breeds that forget this basic truth [that violence settles most anything] have always paid for it with their lives and freedom" (27).
I'm tempted to call this novel nostalgic, for all of its debatable purpose and philosophy. Of course I wouldn't be the first to call it so, and part of the reason the jacket calls it "The controversial classic of military adventure" is the long history it has spawned of civilian readers being to some degree upset or suspicious of the almost fond way in which this future society of citizenship through military service is described; but still I had promised myself going in that I was going to try and find Heinlein's real philosophy behind the novel.