Big ideas matter in politics, and they spark fierce debates about the future of our society. This pathbreaking new textbook examines the key political ideas that shape our lives today. Political Theory: Why Big Ideas Matter takes a unique disruptive approach by creating conversations between two or three important thinkers, within multiple cultural contexts and perspectives to show innovative connections between thinkers across time and space. Rather than drawing solely from the established 'canon' of traditional political thought, which has been criticised for being too white, too male, and too Western, this book is part of a worldwide effort to contest and diversify. Have big ideas on sovereignty been fundamental to establishing political order, or a tool to justify colonisation? Is John Locke's theory of property fit to answer questions about who owns our data or the matter of reparations? Can the tradition of human rights incorporate non-human species? Is gender performative, and how does this represent the struggles of LGBTQ+ communities? Political theory can get us thinking more deeply about empirical events, but empirical events can also get us critiquing theories for falling short. This textbook is essential for undergraduate and postgraduate students of political theory and shows how we can be better political theorists. Simon Stevens is Senior Lecturer in Political Philosophy at De Montfort University Leicester, UK and is a winner of the Political Studies Association Bernard Crick Prize for Outstanding Teaching.