The debate between the realist and idealist schools of international relations is definitely not a unique one to American politics in relation to foreign policy, however this divide has often been most clearly illustrated in the running of American foreign policy. Woodrow Wilson, Jimmy Carter and Ronald Reagan are often viewed as the most striking examples of idealism in foreign policy, they have seen America's role as a moral crusader fighting for the classically American ideals of democracy, free-markets and human rights. Whereas Theodore Roosevelt, Richard Nixon and Henry Kissinger are usually remembered as having viewed foreign policy primarily as a tool for the use in the pursuit of power and national interests.
Realism in its most concentrated form argues that the head of state should solely be interested in achieving things which will further national interests, with complete disregard for things like human rights if they don't directly contribute to this achievement.
A common explanation for the realist way of thinking is concisely put when it is stated that, 'leaders must deal with the world the way it is, not as they would wish it to be. The key assumptions of realism say that; states are the main components of the international system and that these states are motivated and ought to be motivated by their own interests and the search for power. It is also assumed that; the balance of power is imperative to international stability and that relations between states should be trying to obtain this international balance of power, not to change other states policies. During the presidential debate of 11th of October 2000, when George W. Bush was asked to speak about what the guiding principle for his foreign policy would be, he took a classic realist line:
"The first question is what's in...