This thesis seeks to challenge the dominance of liberal accounts of legitimacy and support, and to remedy various faults it identifies in the literature with a rival account rooted in critical realism. Its overarching aim is to shift the focus away from ideal-theory hypotheses about what defines a 'perfect' structure, towards how agents think about and approach politics and ethics. It provides an overview of the status quo of liberal theorising about legitimacy and political support, followed by four methodological criticisms of the liberal approach: on the liberal treatment of agents with divergent views; the liberal conceptualisation of legitimacy; the blurring-together of legitimacy and political support; and political praxis concerns (p...