‘Autism’ or ‘Autism Spectrum Disorder’: Does either represent a natural kind of psychological disorder?

In DSM-5, ‘autism spectrum disorder’ (ASD) is a new diagnostic category effectively replacing the previous category of ‘autism’. In this paper I question whether either effectively represents a psychological natural kind with significant scientific and explanatory value. Despite the new categorisation, ‘ASD’ and ‘autism’ are effectively synonymous, and current understandings of ASD are based largely on previous research focused specifically on autism. However, there has been no stable consensus over the past 40 years about what autism actually is. No biological explanation has been discovered, and no single psychological theory can account for the heterogeneity of autistic symptoms. A recent large-scale population-based study failed to identify a unifying cognitive account of the variety of symptoms of autism. In the philosophy of science literature, there are widely accepted accounts of natural kinds which emphasise their role in scientific explanations and induction. These claim that natural kinds can typically be identified by clusters of properties which are held together by causal processes and which reflect the causal structure of the world in terms of their explanatory and predictive value. However, the concept of ASD fails to indicate any causal explanation and has very limited discriminant and predictive validity. Consequently ASD, as a diagnosis, cannot plausibly be seen as a psychological natural kind, since it does not appear to function as a powerful explanatory concept in science. Psychologists involved in autism diagnostic services should try to explain more clearly what it is that they believe they are diagnosing.