Wilsonian refers to the basic idealistic principles of President Woodrow Wilson as a formula to end World War I and achieve a world without war; it also assumed an altruistic role for the United States of America. At the time, it meant his opposition to militarism and aristocracy, and his design for a League of Nations to keep the peace by reflecting the will of the people (which he assumed was basically hostile to war). It includes the notion of national self-determination and opposition to colonial empires, a theme picked ip in Ireland, India, Eastern Europe, and the Middle East, which remains influential in the 21st century. It may involve the use of military force as a last resort, although it did not contemplate preventive war.
At its most basic, Wilsonian indicates "idealism" in foreign policy, as opposed to a "realistic" foreign policy that seeks to gain specific economic or military benefits for the nation. Francis Fukuyama, in America at the Crossroads: Democracy, Power, and the Neoconservative Legacy, discusses a "realistic Wilsonianism" as a synthesis of approaches to foreign policy for democracies. Andrew Bacevich also describes it is a basis for the thinking of Ronald Reagan and the post-Cold War period.
God was satisfied with Ten Commandments. Wilson gives us fourteen. — Attr. Georges Clemenceau
The most famous expression was the Fourteen Points of 1918, that expressed Wilsonian war aims, and which Wilson personally worked to achieve at the Paris Conference of 1919. He was quite successful there but refused to include Republican leaders to help broaden the base of support for Wilsonianism. As a result Henry Cabot Lodge demanded amendments to the Treaty of Versailles that Wilson rejected; the Senate failed to pass the Treaty and the U.S. never joined the League of Nations. Americans of the 1920s and 1930s largely rejected Wilsonianism; in the 1930s isolationism came into fashion.
An interventionist form of Wilsonianism was revived after 2001 by President George W. Bush and his neoconservative advisors, who carried out an aggressive policy of democracy promotion in the Middle East, including invasions of Afghanistan (2001- ) and a preventive war in Iraq.