I owe you a dinner invitation, you owe ten years on your mortgage, and the government owes billions. We speak confidently about these cases of debt, but is that concept clear in its meaning? This book aims to clarify the concept of debt so we can find better answers to important moral and political questions.

This book seeks to accomplish two things. The first is to clarify the concept of debt by examining how the word is used in language. The second is to develop a general, principled account of how debts generate genuine obligations. This allows us to avoid settling each...