Which factor, self-interest or idealism, was more important in driving American foreign policy in the years 1895-1920?
American foreign policy in most eras has combined elements of both self-interest and idealism, and the period from 1895-1920 is no exception. Indeed most of the United States' relations with other countries during this time could reasonably construed either way. Take the Spanish-American War of 1898, for example. As well as the immense strategic importance of Cuba (self-interest), the United States also backed the Cubans in their revolt against Spanish colonialism (idealism). Whatever the prime motivation for America's involvement with Cuba, there can be little doubt that the war with Spain precipitated an increasingly assertive and expansionist foreign policy.
This development can be seen most clearly in the following year's war between the United States and the Philippines. Having expelled the Spanish from their East Asian colony, the Americans believed that they were entitled to take position of the Philippines. Immediately, this placed them at odds with a growing Filipino independence movement which didn't want to replace one colonial overlord with another. Yet large swathes of American opinion saw war with the Philippines as benevolent in intent, if not necessarily in outcome. Many genuinely believed that an American military presence was necessary to prevent another European power from taking advantage of the situation and imposing their own brand of colonialism on the islands.
The entry of the United States into World War I had some degree of idealistic coloring to it. And there can certainly be doubt as to the commitment of Woodrow Wilson to high-minded principles of democracy and national self-determination. That said, there were also pragmatic concerns to be taken into consideration. For one thing, most of the Allied powers were heavily indebted to American banks and other financial institutions. If they lost the war, then they would default. So it was certainly in the interests of Wall Street for the United States to intervene. Also, the increasingly aggressive campaign of submarine warfare by the Germans was seriously disrupting America's lucrative trade with Europe.
But after the Senate flatly rejected the League of Nations, what little that remained of idealism in American foreign policy quickly evaporated. The election of Warren Harding in 1920 heralded a new era of "normalcy," in relation to both domestic and foreign affairs. In terms of foreign policy this led to a growing isolationist sentiment among both policy-makers and general public alike. However, in due course, many came to see that isolationism was not necessarily synonymous with self-interest. But this process took a long while to seep into the public consciousness, and even then it only truly came to fruition after the United States had been directly attacked at Pearl Harbor in 1941.
This time period really should be differentiated. The early part of the period was dominated by self-interest while the end of the period had aspects of idealism about it. Overall, I would argue that self-interest predominated, but it would be much clearer if we separated this period into the WWI Era on the one hand and the time before it on the other.
The early part of this time period is dominated by the Spanish-American War and the Roosevelt Corollary to the Monroe Doctrine. These things showed the US doing things like occupying ore even taking other countries (Nicaragua, the Philippines) to promote its own interests.
The WWI era is dominated by Woodrow Wilson and the Fourteen Points. Wilson's goal was to create a world order that would be conducive to peace. This is a much more idealistic motive than was present in the early 1900s.
Overall, I would argue that the self-interest predominated, but that idealism came more to the fore at the end of the period.
During this time period our foreign policy was imperialism, spreading to other nations. Both sides can be argued
The White Man’s Burden - Rudyard Kipling. The idea that it is the duty of the white race to help all others who aren't white because they are savages.
Religion - Many missionaries wanted to expand into other nations in order to spread Christianity
Help Western Hemisphere - Roosevelt Corollary to the Monroe Doctrine If any nation in the western hemisphere appeared politically and fiscally unstable and vulnerable to European control, the US had the right and obligation to intervene.
Reconcentration Camps - Spanish American War 1898. In 1896, Spain instituted reconcentration camps in Cuba. They forced Cubans into these camps to keep them from helping the rebels. 1/3 of people in these camps died from disease and starvation. After we won the war we gained Cuba, Puerto Rico and the Phillipines
Navy - a powerful navy was needed to protect our country and we needed ports to refuel around the world. We gained the Panama Canal by interferring with Columbia and Panama. We first tried to buy the rights to build it and were denied. Afterwards we help Panama gain independence and then had a faster way to travel.
Markets - we needed new places to sell goods too and to get natural resources from. In Hawaii, we overthrew the monarchy to keep the markets.
Power - we wanted to compete with other countries who had lots of colonies
Pride- The DeLome Letter, was written by Enrique Dupuy de Lôme, the Spanish Minister (and Cuba). In a personal letter, he stated President McKinley was weak. We soon went to war with Spain after that