Debates about dedifferentiation: twenty-first century thinking about people with intellectual disabilities as distinct members of the disability group

© 2017 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group. Dedifferentiation describes a shift away from regarding cognitive impairments as the origin of difficulties experienced by people with intellectual disabilities and, instead, regarding their difficulties as socially produced and common to all people with disabilities. This article reviews research evidence concerning the advantages and disadvantages of dedifferentiated policy and service systems for people with intellectual disabilities, the bulk of which addresses education and health service systems. Advantages of dedifferentiation include its avoidance of assumptions about homogeneity, and the stigma of being labelled intellectually disabled; and its support for strong collectives and advocacy that enable people with all types of disabilities to live in the presence of others. For young children, dedifferentiated school and mental health services have positive outcomes not found in similar services for older children and adults. Disadvantages of dedifferentiation include inaccurate or absent representations of unique needs arising from intellectual disability, failure to reduce marginalisation, poor-quality non-specialist mainstream secondary education and health services, and deteriorations in social care. Arguments that dichotomies such as dedifferentiation/differentiation encourage simplification and misconception are reviewed: instead, twenty-first-century thinking negotiates between diverse parties and perspectives. The article makes the case for treating people with intellectual disabilities as members of the broad disability group wherever possible, and for protecting and developing differentiated opportunities, services and research whenever necessary. This requires policymakers and practitioners to balance conflicting ideas more effectively, but it also requires reflection and debate that allow new conceptual tools to emerge. The article concludes by posing three questions intended to encourage reconceptualisation.