Chapter 2: Theories of International Relations & Zombies

2.4: Liberalism

If realism sees the world as a bar fight waiting to happen, liberalism is the friend trying to mediate before anyone throws a punch. While realism views the international system as a battlefield of competing powers, liberalism offers a more optimistic perspective. In contrast to the conflict-focused view of realism, liberalism emphasizes the potential for cooperation and mutual benefit among states. According to liberal theory, international relations don’t always have to be a zero-sum game. States can work together through diplomacy, trade, and shared institutions to achieve common goals, reduce conflict, and foster peace. By focusing on the ways states can cooperate, liberalism highlights a more collaborative, interconnected world where power is not just about military might but also about influence, attraction, and collective action.

One of the key ways liberalism sets itself apart from realism is in its emphasis on soft power—the ability of a state to influence others not through coercion or force, but through attraction, persuasion, and legitimacy. Coined by political scientist Joseph Nye, soft power reflects a state’s capacity to shape the preferences and behavior of others by making its values, culture, and institutions appealing. In contrast to realism’s focus on survival and power maximization, liberalism believes that cooperation, mutual benefits, and shared norms can shape global politics. Tools of soft power include diplomacy, cultural exchange, education programs, and the global promotion of ideas like democracy and human rights. For example, the international popularity of American movies, music, universities, and technology brands isn’t just cultural fluff—it’s a form of influence that helps legitimize U.S. leadership and foster goodwill. From a liberal perspective, this kind of influence makes conflict less likely, as states are more inclined to cooperate with countries they admire and share values with.

A powerful illustration of soft power at work can be found during the Cold War, when the United States and the Soviet Union competed not only through arms races and proxy wars, but also through a battle of ideologies and lifestyles. The U.S. promoted consumerism, political freedom, and pop culture as part of a broader campaign to portray liberal democracy as the more desirable model. Meanwhile, the Soviet Union advanced a counter-narrative centered on socialism, equality, and collective identity. This rivalry played out in radio broadcasts, Olympic games, educational exchanges, and even in space exploration—each side trying to convince the world that its way of life was superior. Liberal theory sees this as a clear demonstration that ideas and institutions matter, and that the ability to win hearts and minds is as strategically important as military force. Soft power is central to the liberal belief that international influence can be built through cooperation, respect, and shared identity—not just dominance.

Liberalism also underscores the importance of institutions in fostering cooperation between states. Institutions are the rules, norms, and organizations that structure state behavior in the international system. These can include formal entities like the United Nations, the World Trade Organization, or the International Monetary Fund, as well as informal norms that guide state interactions. Institutions provide a framework for resolving disputes, creating trust, and promoting cooperation. For example, the European Union has created a complex set of rules and institutions that not only facilitate economic cooperation but also prevent conflicts between member states. By providing regular forums for dialogue, monitoring compliance, and offering mechanisms for conflict resolution, institutions reduce the unpredictability and mistrust that often lead to war.

Liberalism envisions the international system as capable of producing positive-sum outcomes, where cooperation benefits all parties involved. In a positive-sum scenario, states aren’t competing for limited resources where one side’s gain equals another’s loss. Instead, they can all benefit through collaboration. Trade agreements, for example, often create positive-sum dynamics where all participating countries can enjoy economic growth, improved standards of living, and access to goods. The success of global trade organizations, like the World Trade Organization (WTO), is rooted in the idea that trade can generate benefits for all involved, as long as there are fair rules in place. This stands in contrast to the zero-sum thinking of realism and demonstrates how, from a liberal perspective, international politics can be about win-win outcomes.

The concept of interdependence lies at the heart of liberal international relations theory. It refers to the mutual reliance between states, especially through economic connections like trade, finance, and supply chains. Liberals argue that as states become more economically interwoven, the incentives for violent conflict diminish—because war would not just harm enemies, but hurt one’s own economy in the process. This idea became especially prominent in the work of Robert Keohane and Joseph Nye, who introduced the concept of “complex interdependence” in the 1970s. They challenged the realist assumption that power politics and military force always dominate international outcomes. Instead, they argued that in a highly connected world, economic, environmental, and technological issues create overlapping interests that make cooperation both necessary and beneficial. In this framework, diplomacy, international institutions, and global markets play a larger role in fostering peace than tanks or missiles.

A powerful example of interdependence in action is the economic relationship between the United States and China. Despite rising tensions over trade policies, cybersecurity, and regional influence, the two countries remain deeply connected through massive bilateral trade, foreign direct investment, and supply chain integration. American companies depend on Chinese manufacturing, while Chinese growth relies heavily on exports and access to U.S. markets. While political leaders on both sides have voiced concerns—and even engaged in trade disputes—these economic ties act as a form of restraint, making outright conflict less likely. Liberal theorists argue that this web of mutual economic interest raises the cost of war to a level that discourages aggressive action. In essence, why bomb your trading partner when both of your stock markets would tank? Interdependence doesn’t eliminate conflict entirely, but it shifts state behavior toward negotiation, compromise, and economic diplomacy over brute force.

Another important liberal concept is collective security, which suggests that peace can be maintained when states agree to protect one another against aggression. In a collective security system, an attack on one member is considered an attack on all, prompting a united response. The most famous example of this is NATO, where members have pledged to defend each other in case of external aggression. This idea stands in contrast to the balance of power thinking in realism, where states constantly seek to counterbalance potential threats. In a collective security arrangement, the goal is not to prepare for inevitable conflict but to prevent it altogether by deterring aggressors through the promise of a coordinated response.

A key contribution of liberalism to international relations is the Democratic Peace Theory, which posits that democracies are significantly less likely to go to war with one another. This theory is grounded in the belief that democratic states share certain structural and cultural characteristics that reduce the risk of conflict. These include transparency in decision-making, public accountability, free press, and checks and balances that make it more difficult for leaders to engage in aggressive or unilateral military actions. In democracies, leaders must answer to voters and legislatures, and there is often robust debate over the costs and justifications of war. The roots of this idea go back to Immanuel Kant’s 1795 essay Perpetual Peace, in which he argued that a federation of republican states could lead to lasting peace. Modern liberal scholars like Bruce Russett (1993) and Michael Doyle (1983) have provided empirical support for the theory, highlighting how democratic norms and institutions constrain violent behavior between democratic nations.

Empirical studies of international conflict support the Democratic Peace Theory, showing that while democracies do go to war, they rarely go to war with each other. A widely cited example is the long-standing peace between the United States and Canada, two mature democracies with deep economic ties, shared cultural values, and strong political institutions. Despite occasional disagreements—over trade, Arctic sovereignty, or defense spending—the relationship has remained peaceful for well over a century, largely managed through diplomacy rather than force. This stands in contrast to relations between democracies and non-democracies, where conflict remains more likely. From a liberal perspective, this pattern offers hope: if democracy can spread globally, so too can the zones of peace. The Democratic Peace Theory thus reinforces liberalism’s optimistic vision—that through shared governance, norms, and cooperation, the international system can become more stable, less violent, and more just over time. But would this peaceful behavior continue in the face of hordes of the undead at your doorstep?

Liberalism: Fighting Zombies with Friendship and Committees

If realism prepares for a zombie apocalypse by building walls and stockpiling weapons, liberalism is busy organizing a global task force and drafting a “Zombies Without Borders” treaty. Liberalism would focus on cooperation and collective action to combat the zombie threat. Liberals believe that, despite the anarchic nature of international politics, states can work together through institutions and diplomacy to overcome shared challenges. The outbreak of zombies would prompt immediate international collaboration, with states working through institutions like the United Nations or the World Health Organization to coordinate responses, share information, and allocate resources. In World War Z, we see hints of this liberal approach when scientists and governments collaborate to find a cure, emphasizing that cooperation is not only possible but essential for global survival. Check out the following scene from World War Z to see how the UN might use its global cooperative power to respond to a zombie outbreak.

The liberal emphasis on interdependence would be crucial in a zombie apocalypse, reinforcing the idea that no state can survive alone—especially when facing a relentless, borderless threat. Since zombies don’t respect national boundaries, the survival of any one state is directly tied to the survival of others. Even the most fortified nations would quickly realize they depend on global trade for essential supplies like food, medicine, and fuel. Additionally, medical research must be shared to develop a vaccine or cure as quickly as possible, ensuring that scientific breakthroughs benefit all of humanity rather than being hoarded for strategic advantage. Liberalism would also highlight the importance of positive-sum outcomes, where cooperation leads to mutual benefit rather than cutthroat competition. Instead of stockpiling resources and viewing others as threats, states could pool their expertise, infrastructure, and technological advancements to combat the zombie crisis more effectively. One country might develop a treatment, another might have the manufacturing capacity to mass-produce it, and another could provide the logistics to distribute it globally. Rather than descending into chaos and conflict, liberalism suggests that states would recognize their shared interests and work together, proving that even in an apocalyptic crisis, diplomacy, institutions, and cooperation remain essential tools for survival.

Liberalism, with its focus on cooperation, interdependence, and institutions, offers a compelling alternative to the more conflict-driven worldview of realism. However, just like realism, it has its limitations and critics, especially when cooperation fails, or when institutions are unable to prevent conflict. In the next section, we’ll explore constructivism, a theory that highlights the role of ideas, identities, and norms in shaping international relations, providing yet another lens through which to understand global politics.