Internationalism
Working Men of All Countries, Unite!
— Karl Marx, Final line of The Communist Manifesto (1848)
Internationalism is the belief that leftist solidarity should not end at national boundaries. With regard to theory, it states that the working class shares common interests over the entire globe, and that it is impossible to effectively support the interests of any working people by maintaining activity only within a single country. In revolutionary praxis, it is transnational cooperation and support between leftist organizations, and the effort to unify the struggle into a single worldwide movement. In international politics, it is the movement to organize economic activity collectively and eventually federate all peoples under the banner of the earth.
Its relation to nationalism is not one of simple opposition. There is no inherent contradiction between internationalism and the preservation of national identity. Instead, internationalism is the effort to empower nationalities through mutual solidarity. Leftist internationalism ought to be distinguished from capitalist globalism. Globalism effectively disempowers the world's peoples by subjecting them to the unrestrained discipline of a global market economy.