What are the arguments for and against imperialism?

The supporters of an American empire thought annexing the Philippines would provide economic and military benefits. It would provide the U.S. with a naval base in Asia, and a large market for American goods. They also believed that America had the duty to teach "less civilized" people how to live properly. Those who didn't support annexation thought that the cost to run an empire would outweigh the economic benefits that it provided. They also believed that imperialism violated American principles.