walker has written extensively on the logic of 'inside/outside,' a dichotomy which enables and frames international relations and its theorizations. for walker, border practices and boundary discourses, spatial demarcations and conceptualizations of here/there and us/them, operate as important sites for understanding these 'inside/outside' logics. vaughan-williams, assessing the study of borders within international relations disciplines, praises walker's work for "offering the most sustained engagement with the problem of borders, especially the relationship between the concept of the border of the state and sovereignty, at the intersection of ir and political theory."