This article attempts to theorise critical subjectivity by combining the emergent sociology of critique with the 'reflexive historical sociology' of subjectivity. In order to integrate insights into how subjectivity and critique are mutually constitutive a 'Gnomonic model' is outlined. Key insights of Foucault, Butler and Nietzsche into critical subjectivity are the basis for the model. The 'Gnomonic model' is a geometric diagram which expresses subjective transformation as a rupture within identity, wherein an aspect of experience is critiqued and excised. This prompts recurrent performances of critique which disavow the constitutive rupture within subjectivity, and thereby diffuse critical modes of thought and subject constitution.