It is often assumed that similar domain-specific behavioural impairments found in cases of adult brain damage and developmental disorders correspond to similar underlying causes, and can serve as convergent evidence for the modular structure of the normal adult cognitive system. We argue that this correspondence is contingent on an unsupported assumption that atypical development can produce selective deficits while the rest of the system develops normally (Residual Normality), and that this assumption tends to bias data collection in the field. Based (...) on a review of connectionist models of acquired and developmental disorders in the domains of reading and past tense, as well as on new simulations, we explore the computational viability of Residual Normality and the potential role of development in producing behavioural deficits. Simulations demonstrate that damage to a developmental model can produce very different effects depending on whether it occurs prior to or following the training process. Because developmental disorders typically involve damage prior to learning, we conclude that the developmental process is a key component of the explanation of endstate impairments in such disorders. Further simulations demonstrate that in simple connectionist learning systems, the assumption of Residual Normality is undermined by processes of compensation or alteration elsewhere in the system. We outline the precise computational conditions required for Residual Normality to hold in development, and suggest that in many cases it is an unlikely hypothesis. We conclude that in developmental disorders, inferences from behavioural deficits to underlying structure crucially depend on developmental conditions, and that the process of ontogenetic development cannot be ignored in constructing models of developmental disorders. Key Words: Acquired and developmental disorders; connectionist models; modularity; past tense; reading. (shrink)

What Russell regarded to be the ‘chief outcome’ of his 1914 Lowell Lectures at Harvard can only be fully appreciated, I argue, if one embeds the outcome back into the ‘classificatory problem’ that many at the time were heavily engaged in. The problem focused on the place and relationships between the newly formed or recently professionalized disciplines such as psychology, Erkenntnistheorie, physics, logic and philosophy. The prime metaphor used in discussions about the classificatory problem by British philosophers was a spatial (...) one, with such motifs as ‘standpoints’, ‘place’ and ‘perspectives’ in the space of knowledge. In fact, Russell’s construction of a perspectival space of six-dimensions was meant precisely to be a timely solution to the widely discussed classificatory problem. (shrink)

The turn of the last century saw an explosion of philosophical realisms, both in the United States and in the United Kingdom. Gary Hatfield helpfully asks whether we can impose order on this chaotic scene by portraying these diverse actors as responding to a common philosophical problem—the so-called problem of the external world, as articulated by William Hamilton. I argue that we should not place the American realism that grows out of James’s neutral monism in this problem space. James first (...) articulated his position in response to critical attacks on the methodology he had employed in his psychological research. The direct topic of these criticisms was James’s earlier claim that a scientific psychology must treat knowledge as an inexplicable theoretical primitive. If I am right, then we ought to hesitate about Hatfield’s suggestion that American realism operated inside the same problem space as the early realism of British figures like Russell and Moore. James’s neutral monism first emerged as a conception of knowledge by a psychologist, and it was designed to meet concerns about his scientific research that had been raised by other psychologists. (shrink)