Political philosophy studies the theoretical and conceptual foundations of politics. It examines the nature, scope, and legitimacy of political institutions, such as states. The field investigates different forms of government, ranging from democracy to authoritarianism, and the values guiding political action, like justice, equality, and liberty. As a normative field, political philosophy focuses on desirable norms and values, in contrast to political science, which emphasizes empirical description.

Political ideologies are systems of ideas and principles that outline how society should work. Anarchism rejects the coercive power of centralized governments. It proposes a stateless society to promote liberty and equality. Conservatism seeks to preserve traditional institutions and practices. It is skeptical of the human ability to radically reform society, arguing that drastic changes can destroy the wisdom of past generations. Liberals advocate for individual rights and liberties, the rule of law, private property, and tolerance. They believe that governments should protect these values to enable individuals to pursue personal goals without external interference. Socialism emphasizes collective ownership and equal distribution of basic goods. It seeks to overcome sources of inequality, including private ownership of the means of production, class systems, and hereditary privileges. Other strands of political philosophy include environmentalism, realism, idealism, consequentialism, perfectionism, nationalism, individualism, and communitarianism.

Political philosophers rely on various methods to justify and criticize knowledge claims. Particularists use a bottom-up approach and systematize individual judgments, whereas foundationalists employ a top-down approach and construct comprehensive systems from a small number of basic principles. One foundationalist approach uses theories about human nature as the basis for political ideologies. Universalists assert that basic moral and political principles apply equally to every culture, a view rejected by cultural relativists.

Political philosophy has its roots in antiquity, such as the theories of Plato and Aristotle in ancient Greek philosophy, with discussions on the nature of justice and ideal states. Confucianism, Taoism, and legalism emerged in ancient Chinese philosophy, while Hindu and Buddhist political thought developed in ancient India, each offering distinct views on the foundations of the social order and statecraft. Political philosophy in the medieval period was characterized by the interplay between ancient Greek thought and religion in both the Christian and Islamic worlds. The modern period marked a shift towards secularism as diverse schools of thought developed, such as social contract theory, liberalism, conservatism, utilitarianism, Marxism, and anarchism.

Political philosophy is the branch of philosophy that studies the theoretical and conceptual foundations of politics. It considers the relation between individual and society, the best organization of collective human life, the distribution of goods and power, the limits of state authority, and the values that should guide political decisions. The field examines basic concepts such as state, government, power, legitimacy, political obligation, justice, equality, and liberty, analyzing their essential features and how they influence citizens, communities, and policies. Schools of political philosophy, such as liberalism, conservatism, socialism, and anarchism, offer diverse interpretations of these concepts. They are guided by different values and propose distinct frameworks for structuring societies. As a systematic and critical inquiry, political philosophy scrutinizes established beliefs and explores alternative views. A central motivation for this investigation is that forms of government are not predetermined facts of nature but human creations that can be actively shaped to the benefit or detriment of some or all.

Political philosophers address various evaluative or normative issues. They examine ideal forms of government and describe the values and norms that should guide political decisions. They differ in this regard from political scientists, who focus on empirical descriptions of how governments and other political institutions actually work, rather than how they ideally should work. The term political theory is sometimes used as a synonym of political philosophy, but can also refer to a sister discipline. According to the latter view, political philosophy seeks to answer general and fundamental questions, whereas political theory analyzes and compares more specific aspects of political institutions and clarifies the concepts and methods used by political scientists.

Political philosophy has its roots in ethics—the area of philosophy studying moral phenomena—and is sometimes considered a branch of ethics. While ethics examines right conduct and the good life in the broadest sense, political philosophy has a more narrow scope, focusing on the organization and justification of political institutions rather than private moral obligations not directly related to collective life. Political philosophy is also closely related to social philosophy, and philosophical treatises often discuss the two together without clearly distinguishing between them. Despite their overlap, one difference is that social philosophy examines diverse kinds of social phenomena, while political philosophy has a more specific focus on power and governance. Because of its interest in the role of laws and economic structures, political philosophy is also connected to the philosophy of law and economics.

The term political philosophy originates in the ancient Greek words πολιτικός (politikos, meaning 'belonging or pertaining to the polis') and φιλοσοφία (philosophía, meaning 'love of wisdom'). As one of the oldest branches of philosophy, it has been practiced in many different cultures, often in response to political challenges of their time by trying to understand, justify, or critique social arrangements.