What did some european imperialists use to justify imperialism?

European imperialists used a variety of methods to justify imperialism. One major reason was the argument that white Europeans were "superior" to the races that were colonized and therefore it was the responsibility of the Europeans to "civilize" the races and groups they were colonizing. 

Ifound this on google “the existence of agglomeration economies is central to the explanation of how cities increase in size and population, which places the phenomenon on a larger scale. the concentration of economic activity in cities is one reason for their development and growth.” i hope this you for what your looking for.