Starship Troopers by Robert A. Heinlein
My rating: 5 of 5 stars
Starship Troopers is, in my opinion, one of the three best military sci-fi novels ever written. It shares that distinction with Ender’s Game and Old Man’s war.
It’s also a good primer on, in the books own words, “moral philosophy”. Though it’s main story is about Johny Rico’s time in the Mobile Infantry and their fight against the pseudo-arachnids (the bugs) most of the novel is the musings of Johny on morals, primarily through his remembrances of his “History and Moral Philosophy” teacher in high school.
The basis of morality according to Heinlein (through his characters) is spelled out in the middle of Chapter 12: “Morals – all correct moral rules derive from the instinct to survive; moral behavior is survival behavior above the individual level – as in a father who dies to save his children.”