This article provides an opportunity to re-think traditional ways of assessing students’ knowledge in mathematics through a discussion of the ethical and philosophical aspects of assessment. This is achieved by applying Bornemark and Cusa’s thinking of humans’ calculating (ratio practices) and reflecting (intellectus practices) capacities on assessment and discussing the possibilities and pitfalls that emerge as these capacities come into use. This is illustrated with the policy and practice concerning the assessment practices of students with intellectual disabilities (ID) in Sweden. The article provides a path for recognizing and reflecting on what kind of knowledge production researchers, teachers, and students contribute to as they engage in assessment. This creates an opportunity to re-think how we fabricate students, knowledge, and mathematics and how we wish to do so in the future.