The network theory of conceptual development is the theory that conceptual developmentmay be represented as a process of constructing a network of linked nodes. The nodes of such a network represent concepts and the links between nodes represent relations between concepts. The structure of such a network is not determined by experience alone but must evolve in accordance with abstraction heuristics, which constrain the varieties of network between which experience must decide. This paper criticizes the network theory on the grounds (...) that current proposals regarding these abstraction heuristics all fail, and further, that, given certain plausible assumptions, no viable account of these abstraction heuristics will be possible. Abstraction heuristics cannot be universal principles of rational thought because virtually no concept is intrinsically unsuitable for use in a true and useful representation of reality. Nor can they be species-specific natural conventions because in that case, it is argued, we would not be able even in principle to learn to understand the language of creatures who used different ones. (shrink)