International Relations is an interdisciplinary subfield within political science. The first theoretical paradigm of International Relations, Realism, was developed in infancy by classical Athenian historian Thucydides in his writings on the Peloponnesian War. Modern political theorists would later be added as founding fathers of the paradigm, including Cardinal Richelieu, Niccolo Machiavelli, and Otto Von Bismarck. As a field of study, however, it would not become concrete doctrine until the 20th century, by scholars including E.H. Carr and Hans Morgenthau. The former being English, and the latter an American academic. Over the course of Realism’s ascendance in both policy-making circles and academia, common assumptions would develop in which most realists agreed upon. These common assumptions include 1) the primary unit-of-analysis in the international system are nation-states. 2) these states are primarily concerned with their survival; maximizing security, power, and autonomy. 3) There is no actor above states, be it global government or 911, to call upon to rescue your state. It is a self-help system in which only agents of your state will look out for the interests of your state.
These three ideas can be classified as the three S’s: statist, survival, and self-help. The common assumption I find to make most sense or be most vital in the study of global politics historically and in contemporary times, is the statist assumption. The primary unit-of-analysis in the international system continues to be the nation-state. There are plenty of empirical examples that show the nation-state is no longer the only actor in the international system. Transnational terrorist organizations, for example, have been the predominant security concern of the U.S. government the past decade. However, the reasons for which these organizations form are, ideological yes, but they form as a response to actions or policy undertaken by states.
The Mujahedeen in Afghanistan formed as both a rebellious force against Soviet aggression, but also formed under the patronage of other nation-states; Pakistan and the United States. So organizations, whether they are militarized or not, often serve as proxies that, in their own struggle, also accomplish goals of their patrons. Hizbollah embedded itself as a paramilitary force in Lebanon. But the organization receives support from the nation of Iran. Without a nation-states patronage, could it have carried out its goals as effectively? Even Al-Quada attempted to receive patronage from Saudi Arabia to fight Iraq after the invasion of Kuwait. When they were denied and the U.S. acted as protector instead, within a multinational coalition, AQ then directed its efforts against those nation-states policy-decisions.
Whether or not a leader embraces a realist worldview or liberal one can depend upon a number of factors, including geography and state doctrine. If you are Bashar Al-Assad, you have little choice in accepting a realist worldview. You’re surrounded by states who would like to see you overthrown. No one can, or is willing to, force Saudi Arabia to stop spending tens of billions of dollars funding your opponents. You can in such a case only rely on your base of support to uphold your claim to the presidency of Syria. Whether or not others will help you, Iran and Russia, is a bilateral decision, not subject to international oversight. Bashar frequently has made the point in media interviews, that when one sovereign government sells goods to another sovereign government, that is fair game. But when a sovereign government sells goods to a rebel group, it is an affront to state sovereignty. When a nation does decide to supply rebels with goods, it can be made by that nation, including when president Obama waived the ban on supplying arms to Syrian rebels.
Norway’s leaders on the other hand can take full advantage of the physical security provided by NATO; the shipping lanes secured by the U.S. Navy; and the international order underwritten by American power, to take part in global trade and secure high standards of living. As long as others continue to be realist in upholding international security measures, Norway can continue to take part in liberal institutions to provide for its people, without having to worry Russia will invade it by sea, as they did by land invade Georgia in 2008. So whether a leader approaches the world as a liberal or realist may not necessarily affect who they engage with in the world, but for what purposes. A realist leader may be more likely to seek military arms from those they approach, while a liberal leader will more likely seek solutions to common problems, like engendering economic growth or capping carbon emissions across both nations (so companies won’t relocate from one to the other). But again, whether they concentrate on arms or trade is likely to be affected by their internal stability and how serious their external competitors are about undercutting them.
The Democratic Party is more open to realism today than the Republican party. The Republican Party historically over the cold war period had the reputation as the more hawkish party, and were considered more trustworthy on issues of national security. Eisenhower, Nixon, Bush senior (and their NSA’s and SOS’s) had reputations as realists. The Democratic Party was still brushing off its Liberal anti-war image decades after the Vietnam War ended. In the post cold war world, the struggle for global hegemony is over, and the struggle for global order, lest we degenerate into global chaos, had begun. The Republican Party is made up almost exclusively now by neoconservatives, ideologues who seek to create a world in which other nations are rebuilt in our image; and isolationists, those who would seek an end to all American obligations overseas, and thus weaken our ability to project power and secure the international order we helped to underwrite. Democrats have their own liberal internationalist wing, but as we saw on multiple occasions during and in the aftermath of the “Arab Spring”, president Obama did not universally intervene on behalf of “free peoples”. He’s sought to draw down America’s wars, retrench, and rebuild the basis of American power (economic and fiscal security). Whether he can succeed in that is more a matter of domestic politics than international. Republicans like Richard Lugar can no longer be considered the mainstream of the Republican Party. The center of gravity in the Democratic Party however, is building on organizations like Center for a New American Security, grand strategy of the Truman administration, and at least try to adhere to the advice of men like Jacob Stokes, Stephen Walt, Leslie Gelb, and Zbigniew Brzezinski.
The neo-liberal case for free trade is part of the Washington Consensus. So who struggles uphill against this consensus most stringently? Difficult on first thought to say. Labor’s been rolling over for decades; tea party conservatives are contradictory in what they’re seeking, tariffs and “buy America” on the one hand, but deregulatory measures and more and more extreme free market ideology on the other. I would say progressives, even if they are ineffectual, are at least more doctrinally in line with protecting against the affects of neoliberalism. They want to expand the welfare state, not shrink it; guarantee a certain standard of living, not undercut it. Progressive’s aren’t very supportive of free trade agreements, though that may not stop progressive congressman from voting for it with the president. The Tea Party mostly supports neoliberalism, they didn’t even support the bank bailouts. They completely avoid accepting state intervention in corporate affairs (free market), preferring rather “personal responsibility” and “individualism”. I think it’s fair to say the Tea Party, at least their representatives, are neoliberals or free-marketeers.
The central argument of the liberal approach to international relations is that certain standards should be upheld by way of institutions of global governance and regulatory measures. These norms should be upheld through bodies that have the power to take up disputes between nations and judiciously settle the matter. Morgenthau would have called this something along the lines of international legalism. The World Trade Organization is an example of one of these bodies. Collective security is necessary to enforce these standards. As we know liberalism shares many of the human nature assumptions that classical realism does. A nation will break the “rules” of international cooperation if the opportunity presents itself and the costs of doing so don’t outweigh the reward. No one consented to Russia invading Finland in 1939, in fact if the Legalism of the League of Nations meant anything it meant that they could not install a puppet government in Finland. But Morgenthau will say that international law is nothing if not backed up by the power to enforce those laws. So collective security, especially of a defensive nature, in some way reinforces international standards of commerce among nations. It tells any nation that would be offensive in its economic actions that others will coalesce to protest or take action against it. Once this is normalized, and nations acquiesce to the rules imposed, trade, rather than security, becomes far more important. It is when others no longer feel like acquiescing that collective action is necessary.
 The Twenty Years’ Crisis 1919-1939: An introduction to the study of international Relations  Politics Among Nations: The struggle for Power & Peace  Defensive Realism & Offensive realism  Accredited to Zbigniew Brzezinski, perhaps the most realist democrat of the 60s-80s.  Truman National Security Institute  Research Associate CNAS, Harvard professor, President Emeritus CFR, NSA under Carter.