Supporters of this principle are referred to as internationalists, and generally believe that the people of the world should unite across national, political, cultural, racial, or class boundaries to advance their common interests, or that the governments of the world should cooperate because their mutual long-term interests are of greater importance than their short-term disputes.
In 19th-century UK there was a liberal internationalist strand of political thought epitomized by Richard Cobden and John Bright. Cobden and Bright were against the protectionist Corn Laws and in a speech at Covent Garden on September 28, 1843 Cobden outlined his utopian brand of internationalism:
Free Trade! What is it? Why, breaking down the barriers that separate nations; those barriers behind which nestle the feelings of pride, revenge, hatred and jealously, which every now and then burst their bounds and deluge whole countries with blood...
Cobden believed that Free Trade would pacify the world by interdependence, an idea also expressed by Adam Smith in his The Wealth of Nations and common to many liberals of the time. A belief in the idea of the moral law and an inherent goodness in human nature also inspired their faith in internationalism.
Such "liberal" conceptions of internationalism were harshly criticized by socialists and radicals at the time, who pointed out the links between global economic competition and imperialism, and would identify this competition as being a root cause of world conflict. One of the first international organisations in the world was the International Workingmen's Association, formed in London in 1864 by working class socialist and communist political activists (including Karl Marx). Referred to as the First International, the organization was dedicated to the advancement of working class political interests across national boundaries, and was in direct ideological opposition to strains of liberal internationalism which advocated free trade and capitalism as means of achieving world peace and interdependence.
Other international organizations included the Inter-Parliamentary Union, established in 1889 by Frédéric Passy from France and William Randal Cremer from the United Kingdom, and the League of Nations, which was formed after World War I. The former was envisioned as a permanent forum for political multilateral negotiations, while the latter was an attempt to solve the world's security problems through international arbitration and dialogue.
J. A. Hobson, a Gladstonian liberal who became a socialist after the Great War, anticipated in his book Imperialism (1902) the growth of international courts and congresses which would hopefully settle international disputes between nations in a peaceful way. Sir Norman Angell in his work The Great Illusion (1910) claimed that the world was united by trade, finance, industry and communications and that therefore nationalism was an anachronism and that war would not profit anyone involved but would only result in destruction.