International Relations

International relations (IR) is an academic discipline devoted to the study of political, economic and social interactions that occur across national borders. It encompasses the analysis of diplomacy, war, foreign policy, trade and the behaviour of sovereign states within the international system, as well as the role of global actors such as intergovernmental organisations, international courts, multinational corporations and non-governmental organisations. Although the study of international politics can be traced back to antiquity, IR emerged as a distinct academic field in the early twentieth century and has since developed into a major multidisciplinary branch of political science.

Scope and Definitions

International relations examines how autonomous political entities interact in a world without a central overarching authority. In many academic institutions, it is classified as a subdiscipline of political science alongside comparative politics, political philosophy, political methodology and public administration. In other settings, IR is treated as a broader interdisciplinary field that integrates politics, international law, global economics, history, sociology, geography and anthropology.
The terminology varies by institution. In Scandinavia, the field is commonly referred to as international politics, whereas universities such as the London School of Economics use the term international relations to denote multidisciplinary study. Undergraduate degrees in IR often lead to specialised postgraduate programmes in diplomacy, political science, international law or global economics.
A seminal early description by Frederick S. Dunn in the inaugural issue of World Politics highlighted that IR concerns interactions across national boundaries involving autonomous political groups. He differentiated international politics, international economics and international law by their distinct relationships to sovereignty and state power.

Historical Development

Although modern IR as a discipline began in 1919 with the establishment of the first academic chair at Aberystwyth University, the intellectual foundations of the field reach back much earlier. Ancient and early modern texts analysing statecraft and conflict influenced later IR theories. Notable works include:

• The Art of War by Sun Tzu
• History of the Peloponnesian War by Thucydides
• Arthashastra by Chanakya
• Leviathan by Thomas Hobbes
• The Prince by Niccolò Machiavelli

These writings informed the realist tradition, which emphasises power, survival and the competitive nature of international politics.
A key historical reference point in IR is the development of the modern state system founded on the principle of sovereignty. The Peace of Westphalia of 1648 is often cited as the origin of the sovereign state order, although scholars note that elements of overlapping authority persisted, particularly in the Holy Roman Empire. The Treaty of Utrecht in 1713 further consolidated the idea that sovereigns possessed no external superiors and no internal equals.
Between 1500 and 1789, diplomacy, multilateral relations and professional militaries became institutionalised across Europe. The French Revolution introduced the notion of national, rather than monarchical, sovereignty, influencing the emergence of the modern nation-state. Competing models of nationhood developed in this era, notably the civic-republican model associated with France and the ethnic-linguistic variant prominent in German-speaking territories.
European concepts of sovereignty and international law were exported globally through colonisation. During the twentieth century, global decolonisation and the Cold War established the contemporary state system. However, not all states adhere to strict Westphalian principles: some are regarded as premodern, while others in highly integrated regions can be considered postmodern.

Major Theoretical Perspectives

International relations theory emerged formally after the First World War and has since expanded to include several key schools of thought:

• Realism, emphasising power politics, state survival and an anarchic international system.
• Liberalism, focused on cooperation, international institutions and interdependence, drawing upon the ideas of Immanuel Kant and Jean-Jacques Rousseau.
• Constructivism, examining how ideas, identities and norms shape state behaviour and global interactions.

Other influential perspectives include Marxist approaches, postcolonial theory, feminism, the English School of international society and critical theory.
IR theory continues to evolve, shaped by globalisation, technological change, transnational challenges and shifts in the balance of power.

Levels of Analysis

To understand the complexity of global affairs, IR scholars use several levels of analysis:

• Individual level: leaders’ beliefs, personalities and decision-making styles.
• State level: domestic politics, institutions, national identity and political culture.
• Interstate level: diplomatic, economic and military interactions between states.
• Global level: systemic patterns, international norms, environmental pressures and technological developments.

These analytical layers assist in examining the causes of war, the dynamics of international cooperation and the nature of global governance.

Key Actors in International Relations

Modern IR recognises that state activity coexists with the influence of global and transnational actors. Major categories include:

• Intergovernmental organisations (IGOs), such as the United Nations, the World Trade Organization and the World Health Organization. Geneva, Switzerland—home to the UN Office at Geneva—hosts more international organisations than any other city and convenes thousands of intergovernmental meetings annually.
• International non-governmental organisations (INGOs), which operate across borders on social, political and humanitarian issues.
• Multinational corporations (MNCs), whose economic presence influences global regulations, trade and investment.
• International courts and tribunals, contributing to the development and enforcement of international law.

These actors highlight that contemporary international relations extends beyond inter-state diplomacy and increasingly involves networks of governance and cooperation.

Evolution During the Twentieth and Twenty-First Centuries

The world wars and their aftermath transformed IR. The Second World War led to a surge in IR scholarship, particularly in North America and Western Europe, where strategic concerns dominated academic and policy agendas. The Cold War entrenched geopolitical divisions and spurred the development of theories addressing deterrence, alliance politics and ideological competition.
After the dissolution of the Soviet Union in 1991, globalisation reshaped international politics, increasing global interconnectedness and raising new issues such as terrorism, climate change, cyber security and economic integration. These developments have prompted new theoretical debates concerning power diffusion, global governance and the nature of the international order.