A Border Within addresses the question of English Canadian identity by exploring whether a plurality of discourses can lead to other than a fragmented society. Ian Angus examines the relationship between globalizing social movements and the particularities of identity politics by extending the theories on identity of Harold Innis and George Grant, two seminal figures in Canadian political philosophy, to develop a philosophy applicable to the contemporary social issues of multiculturalism and environmentalism.

The border is the governing metaphor of the book. Angus argues that English Canadian identity revolves around maintaining a border between Canada and the United States, and suggests that the border between countries can also be seen as a border between self and Other, between humanity and nature. Multiculturalism and the ecology movement's rethinking of the relation between humanity and nature suggest that English Canadian social and political philosophy is oriented toward sustaining a border between self and Other, in order to preserve what is one's own while maintaining and respecting the Other.

Angus argues that contemporary public discourse is hampered both by the tribalizing devolution of the politics of identity and the globalizing forces of corporate political economy. Addressing this impasse requires a new understanding of the politics of identity in English Canada and the creation of a theory of Canadian social identity as postcolonial, particularist, and pluralist.