Why should we obey the law? Why should we willingly sacrifice life, liberty, and property to preserve our political community? Which laws are authorized? Which exceed government's authority? What kind of community merits our allegiance today? What do we owe fellow citizens, prospective immigrants, and foreign communities? A Philosophical Theory of Citizenship addresses these and other seminal questions about legal obligation, government authority, and political community. It rejects contemporary political philosophy's anti-foundational conventions by building its arguments from the ground up on an innovative, idiomatic theory of reality, ethical conduct, and the self. It employs this theory to provide scholars and students with a concise, wide-ranging defense of patriotic duty, classical liberty, and national sovereignty.