The US Constitution discusses how a good country should be run by "the consent of the governed." This is a concept that basically states that the US government should cater to the needs/wants of the citizens. In this case, imperialism would be seen as going against this idea. This is because imperialism involves taking over a country/territory and establishing systems that will benefit America. This meant that the people who were being taken over didn't necessarily want the US to be there anyways.