It is widely held that moral reasons are universalizable. On this view, when I give a moral reason for my action, I take this reason to apply with equal normative force to anyone placed in a relevantly similar situation. Here, I offer an interpretation and defense of Iris Murdoch's critique of the universalizability thesis, distinguishing her position from the contemporary versions of particularism with which she has often been mistakenly associated. Murdoch's argument relies upon the idea that moral concepts may (...) take on idiosyncratic meanings that are unique to a particular individual. Consequently, an agent may conceptualize her situation in such a way that it would not make sense to imagine anyone else facing it. For such an agent, it would be meaningless to say that she took her reasons to apply to anyone other than herself. I defend Murdoch’s argument through an extended analysis of a literary example, and consider and reject four possible lines of objection. Finally, I consider the consequences of the argument for our understanding of the nature of moral reasoning and what Murdoch describes as the ‘endless task’ of love. (shrink)