A new approach to democratic theory that empowers its citizens. Democracy is a complex social system. A Systemic Theory of Democracy investigates the complexity of democracy's functioning through a systemic perspective to identify opportunities and challenges for democratic transformations. It critically reappraises social systems theory, extracting critical tools to describe and evaluate dynamic and ever-evolving democratic systems within their changing societal environment. By articulating political functions, social practices, and democratic principles, this systemic framework transcends theoretical models' boundaries, enabling it to map existing political systems and identify their context-specific shortcomings. A systemic approach to democracy, argues political researcher Victor Sanchez-Mazas, opens the road for the possibility and necessity for citizens to identify the problems faced by their democratic system. A Systemic Theory of Democracy calls for a critical democratic agenda: the constant diagnosis of democratic shortcomings, by citizens themselves and through democratic processes. This book introduces democratic diagnosis as a major challenge and opportunity for both contemporary democratic theory and existing democratic systems.