Research in mathematics education has long identified the ideology of certainty as central to mathematical instruction and to the way in which mathematics is (mis)used in social and political discourses. As we will see, this ideology is not merely a matter of individual beliefs, but is deeply embedded in the material practices and power structures of schooling. Thus, a complex interdependency underscores the relationship between ideological transformation and transformation of specific instances of mathematical instruction. Partially tracing this interdependency will serve to discuss both the social potential of educational proposals aimed at countering the ideology of certainty as well as the difficulties entailed in enacting them.