Is there a core national doctrine?

National doctrines are notoriously diverse, and often embody contradictory political values and criteria for membership. This article asks whether there is a ‘core’ national doctrine that connects republican, cultural, ethnic and liberal concepts of nationality. It considers two attractive candidates: one locating the ‘core’ in a doctrine about the political and psychological significance of pre‐political cultural identities, the other in the constitutional principle of popular sovereignty. After assessing the limitations of both, I sketch a different core national doctrine. This doctrine is constitutive and geopolitical, not constitutional or cultural. It has deep roots in the security concerns specific to the modern, pluralistic system of sovereign states, and prescribes in general terms the form that any community should take in order to survive or distinguish itself in that system. It says very little about the appropriate basis for such communities; the choice of political, cultural, ethnic or even racial criteria is left wide open. More than other versions, this ‘core’ is able to identify the common ground between cultural, constitutional, and other national doctrines. It also puts a sharp focus on the reasons why, historically, national and liberal values have been so hard to combine.