Key Theories of International Relations

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Realism in International Relations

International relations theories can help us understand the way the international systems work, as well as how nations engage with each other and view the world. Varying from liberal, equality-centric strategies to straightforward realist concepts, international relations theories are often used by diplomats and international relations experts to dictate the direction that a government may take in regards to an international political issue or concern. By studying the following key international theories, professionals in the field can better discern the motivations and goals driving policy decisions worldwide.

Realism is a straightforward approach to international relations, stating that all nations are working to increase their own power, and those countries that manage to horde power most efficiently will thrive, as they can easily eclipse the achievements of less powerful nations. The theory further states that a nation’s foremost interest should be self-preservation and that continually gaining power should always be a social, economic, and political imperative.

The nature of realism implies that seeking a moral high ground is a goal that governments cannot always achieve and that deceit and violence can be highly effective tools for advancing national interests. With homeland defense elevated to the highest priority, remaining morally righteous in the eyes of international organizations can take a backseat to enforcing foreign policy that will improve the nation’s global stature. In modern times, realism is evident in the foreign policies of China and Russia. The relationship between Russia and Syria is one that has raised eyebrows in Europe and around the world; despite the bloody civil war in Syria—and the international community’s pleas for intervention—Russia has maintained strategic relations with the government of Bashar Al-Assad in order to protect Russian interests in the region. Similarly, China continues its diplomatic and economic association with North Korea in spite of the latter’s abysmal human rights record and aggressive nuclear testing. Chinese encroachment into the South China Sea and Russia’s incursions into Ukraine also highlight the two countries’ aggressive—and at times violent—realist political approach to international affairs.


Also called “liberal internationalism,” liberalism is based on the belief that the current global system is capable of engendering a peaceful world order. Rather than relying on direct force, such as military action, liberalism places an emphasis on international cooperation as a means of furthering each nation’s respective interests. Liberalists believe that the negative consequences of force—such as economic losses and civilian casualties—far exceed its potential benefits. Therefore, liberal politicians generally prefer the use of economic and social power in achieving their national goals (for instance, obtaining the agreement of a neighboring country to help secure a border). In today’s globalized society, using economic tactics—such as bilateral trade agreements and international diplomacy—can be more effective in advancing political interests than threatening force. As liberalism has become more rooted in international cooperation through the establishment of organizations like the United Nations, realism has started to wane as a viable political strategy. It can be argued that the liberalist tradition, perpetuated by the United States, has become the dominant system in international relations, with established values and international institutions in place to regulate this order.


Constructivism rests on the notion that rather than the outright pursuit of material interests, it is a nation’s belief systems—historical, cultural and social —that explain its foreign policy efforts and behavior. For example, since German aggression served as the primary catalyst for the Second World War, Germany deploys its armed forces outside of German borders only when its government is certain of the need to intervene in instances of genocide or conflict that threatens to spill over into other nations. This has been demonstrated by the country’s foreign policy following the first and second Gulf War (the latter of which Germany refused to participate), as well as its reluctant participation in United Nations-led operations in Somalia and Yugoslavia.

Constructivists also argue that states are not the most important actors in international relations, but that international institutions and other non-state actors are valuable in influencing behavior through lobbying and acts of persuasion. For this reason, constructivism has become a popular and important theory in recent decades as non-state actors like international organizations such as Amnesty International, OXFAM, and Greenpeace gain political influence. International organizations play a role in promoting human rights and making them an international standard to which countries are expected to conform.


Karl Marx was a Prussian philosopher and economist whose works posited that societies could escape the self-destructive nature of capitalist socioeconomic systems by implementing socialist theory into their policies, both locally and abroad. Marxism, a theory that closely analyzes social classes, aims to dismantle the capitalist structure of the international system, as it states that capitalism is no longer practically sustainable in the modern world. Marx believed that private property should be replaced by cooperative ownership, with the emphasis placed entirely on satisfying human needs for consumption, rather than creating private profit. Under an ideal socialist international regime, societies would work together to ensure that basic human needs were met on a global scale. Marxism was a dominant political ideology during the Cold War and inspired socialist revolutions in countries such as China, Vietnam and Cuba. Marxism’s influence can still be felt today, with Vietnamese Prime Minister Nguyen Tan Dung encouraging students to study Marxism in exchange for free tuition. The Marxist revival is not exclusive to current and former communist nations; The 2017 Marxism Festival was hosted by the Socialist Workers Party in London and attracted thousands of activists from across the world. As the global population continues to grow and sustainability becomes increasingly precarious, Marxism remains a relevant topic of discussion for those who advocate the prioritization of human needs over private profit.


Gender issues are a significant concern within global politics, and feminism as an international relations theory seeks to regulate the power derived from (or denied on the basis of) an individual’s gender. Feminists are mostly interested in tracking political and social developments that inhibit success in female populations. When systems of power subtly or overtly tell women they can only fulfill certain roles, those limitations become social norms and perpetuate the cycle. The significance of feminism in international relations is evidenced by the role women play in promoting more just and fair international relations policies. Women like Hillary Clinton and Condoleezza Rice have both made important contributions to the advancement of women worldwide. As a senator representing the state of New York, Clinton co-sponsored the Lilly Ledbetter Fair Pay Act of 2009, which was aimed at combatting gender-based pay discrimination. Rice was instrumental in starting the One Woman Initiative, which provides access to legal rights, political participation, and economic development to women living in countries with a large Muslim population.

Outside of the U.S., the adoption of feminist policies has propelled women to political achievement. Iceland has maintained women’s rights as integral to their political policy since 1850, when the nation granted unconditional inheritance rights to men and women. The nation, which also granted women suffrage five years before the United States in 1915, has also seen women in the highest levels of government: former President Vigdís Finnbogadóttir and current Prime Minister Jóhanna Sigurdardóttir were the first women to be elected to these positions in 1980 and 2009, respectively. The National Committee for the United Nations Development Fund for Women (UNIFEM) in Iceland was established in 1989 and focused on improving the social status of women across the globe. The contributions of nations such as Iceland have been financially and socially impactful, addressing the need for true gender equality and demonstrating the positive effects of feminism in domestic and foreign policy.

With the rapid changes taking place in the current geopolitical landscape, discerning why governments act as they do and understanding the implications of those actions has never been more crucial. When leveraged properly, these theories can be used to accomplish a broad array of objectives; therefore, international relations professionals must possess a keen understanding of the specific impact each theoretical approach to international relations can have on global diplomatic efforts. Obtaining a master’s degree in international relations—such as the Master of Arts in International Relations degree offer by Norwich University—can help individuals deepen their knowledge and understanding of these theories and prepare them for the rigors of a career in international diplomacy.

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As the nation’s oldest private military college, Norwich University has been a leader in innovative education since 1819. Through its online programs, Norwich delivers relevant and applicable curricula that allow its students to make a positive impact on their places of work and their communities.

Our online Master of Arts in International Relations program offers a curriculum which evolves with current events to help you face the future of international affairs. The program covers many subjects to give you a look at the internal workings of international players, examine the role of state and non-state actors on the global stage, and explore different schools of thought. You can further strengthen your knowledge by choosing one of five concentrations in International Security, National Security, International Development, Cyber Diplomacy, or Regions of the World.



Fifty Key Thinkers in International Relations, Google Books
Handbook of International Relations, Google Books
The Globalization of World Politics, Google Books
Realism in International Relations, E-International Relations
How China, The World’s Oldest Marxist State, Proves Marx Wrong, The Atlantic
Vietnam Seeks to Lure Students to Study Marxism with Free Tuition, The New York Times
IR Theory: Problem Solving Theory vs. Critical Theory, E-International Relations
Marxism Festival, Marxism
Women’s Rights and Opportunities, The Office of Hillary Rodham Clinton
One Woman Initiative Fund for Women's Empowerment, U.S. Department of State
Feminism’s Influence on Iceland’s Foreign Policy, E-International Relations