Sensory impairments are widely reported in autism, but remain largely unexplained by existing models. This article examines Kanner's causal reasoning and identifies unsupported assumptions implicit in later empirical work. Our analysis supports a heterogeneous causal model for autistic characteristics. We propose that the development of a standardised framework for analysing autistic characteristics would facilitate the identification of sub-groups and the location of biological markers for genetic variation. We also support a neuroconstructivist model proposing that peripheral sensory abnormalities disrupt compilation of complex skills; impact on synaptogenesis, synaptic pruning and myelination; and subsequently manifest themselves as autistic behaviours. This model explains some of the structural and functional brain abnormalities and many of the perceptual, cognitive and attentional features found in autism.