It was the idea that a colonized people where to immature to handle governing themselves. They needed a Western (white) presence to give them law and order. The British maintained a colonial presence in India on the grounds that the Indians weren't ready to form a modern nation.
The flag of Massachusetts still depicts on a Native American. It used to have the Native American saying "Come here and help us." Europeans were supposed to be rescuing Native peoples from paganism and lawlessness.