What do ethical relations look like in the context of the many injustices that pervade mathematics education? In this paper, I argue, first, that violence is the relation that characterizes much of contemporary mathematics education and, second, that understanding ethical relations requires considering mathematics as an equal actor in creating possible relations rather than simply treating it as a context for human relations. I examine how literature in care theory, emancipatory pedagogies, and mathematics education have framed ethical relationality and suggest that the feminist new materialist conceptualization of response-ability offers several contributions for rethinking agency, justice, and praxis for mathematics teachers concerned with addressing mathematical violence.