For liberals like Martha Nussbaum, Female Genital Mutilation (FGM) has come to mark the boundary of toleration. By impairing physical, sexual and psychological functioning, the likes of Nussbaum believe the non-western practice to fulfil, most clearly, the conditions for proscription according to the harm principle. However, those same liberals assume the western practice of male circumcision, generally, to be benign or, even, necessary. As there is seen to be no harm, there is no reason to intervene. I argue that this assumption is erroneous, highlighting evidence that suggests that, according to the criteria of sexual diminution, pain and coercion employed by liberals to criticize FGM, circumcision can be viewed as a harmful act of Male Genital Mutilation (MGM). I highlight the qualitative similarities in the harmfulness of FGM and MGM in order to establish in Nussbaum an empirical and, I argue, ethnocentric oversight in which the criteria of harm are inadequately applied to the latter. I then attempt to identify the obstacles to Nussbaum’s recognition of this harm, arguing that she is party to culturally constituted beliefs in the medical and sexual necessity of the practice and, importantly, the methodological tenet of gender oppression. Having attempted to explain obstacles to the recognition of harm, I then consider the possibility that Nussbaum’s inconsistency is grounded in toleration of religious obligation, arguing that MGM should stimulate certain liberals to reconsider their engagement with theology. My aim is to enable liberals to overcome, often justifiable, claims of ethnocentricity, in order to develop a consistent approach to harmful cultural practices.