Superheroes don't just make fun characters for comic books and movies. Their powers, and how they choose to use them, are philosophical treasure troves, and few are as rich and complicated as the protagonists in “Watchmen,” which opens in movie theaters around the world this week. “'Watchmen' is an embarrassment of riches to the comics-obsessed philosopher,” said Mark D. White, editor of the book “Watchmen and Philosophy: A Rorschach Test.” The book is one of a series that uses pop culture as an entry point to the sometimes abstract subject of philosophy. Years in the making, “Watchmen” is the big-screen adaptation of the acclaimed 12-issue comic book series by Britons Alan Moore and Dave Gibbons published between 1986 and 1987. Like the books, the movie is set in an alternative 1985 when the United States and the Soviet Union are on the brink of nuclear war. It features costumed vigilantes who have become so unpopular they are now outlawed. But “Watchmen” is far from just popcorn entertainment. Its twisted superhero archetypes, like the tortured do-gooder Rorschach and brainy businessman Ozymandias, take time out from performing death-defying acts to muse on subjects like free will, savior figures and the politics of fear. “In ‘Watchmen,' the philosophy is so explicit that you don't have to dig very hard to find it,” said White, an associate professor in the department of political science, economics and philosophy at the College of Staten Island.