What philosophy justified aggressive western expansion in the early years of the US?

The philosophy that justified aggressive western expansion in the early years of the United States is known as Manifest Destiny. This doctrine emerged in the mid-19th century and held the belief that it was the divine right and destiny of the U.S. to expand its territory across the North American continent. Proponents of Manifest Destiny argued that this expansion was not only beneficial but also preordained by God, promoting the idea that American culture, democracy, and economic systems were superior and should be spread across the continent.

Manifest Destiny served as a moral and ideological justification for the displacement of Native American tribes and the annexation of vast territories, including Texas and California. It fueled a sense of nationalism and provided a rationale for the often violent conflicts associated with westward expansion. This philosophy had a powerful influence on U.S. policy and public sentiment during that period of history, shaping the nation's identity and its geographic boundaries.

In contrast, the other options do not encapsulate the same ideological underpinnings that characterized the thinking behind expansion. Eminent domain refers to the government's right to seize private property for public use, a legal principle rather than a philosophy driving expansion. Globalization concerns international interactions and economic connections, which gained prominence much later. Colonial expansion typically refers to European