`Contemporary thinking on philosophy and the social sciences has been dominated by analyses that emphasise the importance of language in understanding societies and individuals functioning within them; important developments which have been under-utilised by researchers in mathematics education. This book reaches out to contemporary work in these broader fields; drawing on original sources in key areas such as Gadamer and Ricoeurs development of hermeneutics, Habermas work in critical social theory, Schutzs social phenomenology, Saussures linguistics and the post-structuralist analysis of Derrida, Foucault and Barthes. Through examining the writings of these major thinkers it is shown how language is necessarily instrumental in developing mathematical understanding; but a language that is in a permanent state of becoming, resisting stable connections to the ideas it locates. The analysis offered extends from children doing mathematics to teachers inspecting and developing their own professional practices.