 In addition, some philosophers have argued that excluding gays and lesbians from marriage is central to gay and lesbian oppression, making them ‘second-class citizens’ and underlying social discrimination against them. Marriage is central to concepts of good citizenship, and so exclusion from it displaces gays and lesbians from full and equal citizenship: “being fit for marriage is intimately bound up with our cultural conception of what it means to be a citizen … because marriage is culturally conceived as playing a uniquely foundational role in sustaining civil society” (Calhoun 2000, 108). From this perspective, the ‘separate-but-equal’ category of civil unions retains the harmful legal symbol of inferiority (Card 2007, Mohr 2005, 89, Calhoun 2000, Chapter 5; cf. Stivers and Valls 2007; for a comprehensive survey of these issues, see Macedo 2015).