Final answer:
The philosophy described in the excerpt is Social Darwinism, which posits that certain races or social groups are inherently superior and destined to succeed. This ideology justified the colonialist and expansionist attitudes of the 19th century, including Manifest Destiny.
Step-by-step explanation:
The 19th-century philosophy described in the excerpt is Social Darwinism. This ideology, based on Charles Darwin's theory of evolution, was applied to human societies by Herbert Spencer who coined the term 'survival of the fittest.' Social Darwinism suggests that certain races or social groups are inherently superior to others and that their success and expansion are natural outcomes of their superiority. This philosophy justified the colonialist and expansionist attitudes of the era, including the notion that the Anglo-Saxon race was meant to spread its civilization and influence over others deemed less fit or capable.
The concept closely linked to this ideology, Manifest Destiny, also emerged in the same period. It was a widespread belief that Americans were destined by God to expand westward across North America. This expansion was viewed as a way of spreading democracy and Americanizing the inhabitants of the territories. It provided a cultural and religious justification for the expansionist policies and actions of the United States during that period.