This book, inspired by public health policymaking during the Covid-19 pandemic, proposes an innovative capacities-based approach to understanding health at all levels of biological complexity - including at the level of the population. This capacities approach to health is applied to various issues within the philosophy of public health, including the goal of public health, evidence-based public health, the metaphysics of epidemics, public health ethics, and decolonizing public health.   The author advocates for greater attention to be paid to the contextual conditions in which public health policies are to be implemented, for a public health principlism grounded by the enhancement of emergent capacities of populations and those of their members, and for the elimination of contributory injustice in medicine and public health policy.   This book is essential reading for all scholars, researchers and advanced students of the philosophy of public health, health ethics, and public health policy.