When John L. O'Sullivan coined the term "mani-fest destiny" in 1845, it referred to the "destiny" of the United States to occupy and develop the American continent because of its superior institutions and form of government. Relative to its later counterpart, the "old" manifest destiny provided a modest program for the development and population of contiguous areas to the then existent United States. The new manifest destiny at the end of the nineteenth century bespoke a certain arrogance, since it claimed for Americans a superior system of government, a superior culture, and a superior race destined to carry mankind to the highest pinnacle of achievement. Many of the adherents of this philosophy extolled Yankee capitalism as part of the superior culture.
A man worthy of the task of educating the nation to the needs of expansion appeared in the form of Captain Alfred Thayer Mahan, whose major work, The Influence of Sea Power Upon History, 1660–1783 (1890), extolled the virtues of a big navy as the route to national greatness— which required colonies to extend the defense perimeters of a great nation, and a merchant marine to carry trade to and from the colonies that would be defended by the navy. Mahan's great fear was a forthcoming contest with a rising China, and by means of its navy he wished to put the United States in a position that would keep China confined to the Asian continent. In numerous books, articles, speeches, and through his classes at the Naval War College in Newport, Rhode Island, Mahan bombarded Americans with his perception of the need for colonies. Ironically, while his impact was great in the United States, before World War I it was possibly even greater in Germany and Japan. Mahan was not nearly as interested in colonies for their commercial value as for their strategic value, but commerce became a selling point to attract a broad segment of the American public.
Social Darwinism added a sinister bent to the American urge for colonial expansion. American exponents of this pseudoscientific philosophy espoused by the Englishman Herbert Spencer adapted the concept of the survival of the fittest to the new manifest destiny, urging the spread of the Anglo-Saxon race and system of government to the less fortunate peoples of Asia and the Far Pacific. Such proponents of expansion for security motives as Theodore Roosevelt might stress the strategic value of port facilities in the Philippines, but they were drowned out by the more flamboyant spokesmen like Senator Albert Beveridge, who demanded annexation of the whole Philippine archipelago. Roosevelt warned President William McKinley that it was feasible to hold a military naval base to protect American interests in Asia, but possession of the whole of the Philippines would be a commitment that the American people would not support in the long run. His advice was ignored. Again in 1907, Roosevelt referred to the Philippines as an Achilles' heel, which should be given at least nominal independence at the earliest possible moment.
Various answers have been proposed for why Americans, with an anticolonial bias deeply ingrained in their political system, turned to colonialism, or, in other words, what the cause was of the development of the new manifest destiny. Obviously, social Darwinism and the hold that it established on the opinion makers in the United States provide one of the many answers. Richard Hofstadter ascribed America's outward thrust for colonies to what he called the psychic crisis. In The Paranoid Style in American Politics and Other Essays (1965) he argues that the severity of depressions of the period created fears about radicalism that caused the upper-middle and upper classes in the United States to look for some diversion from internal crises, and they found relief by focusing on the expansionist issue. Restless energies, which had concentrated on internal development in the first century of American history, turned in some degree to external adventures, such as Frederick Jackson Turner feared they would with the closing of the frontier in 1890. Missionary enthusiasts saw fields available for the spread of Protestant doctrine. Idealists dreamed of lifting the yoke of European monarchists from the Western Hemisphere and then also from Asia. Some proponents of the Spanish-American War hoped to reunite the North and the South through this uplifting national endeavor. A search for markets motivated some enthusiasts for annexation of the Philippines. A desire to be included among the nations of great powers, which required colonial possessions in the late nineteenth century, proved yet another component to the expansionist movement. But Hofstadter's main emphasis in the psychic crisis rests on internal stimuli for external policy, not the least of which was the contest for political position as each of the major parties struggled to become the repository of public confidence.