The dynamics of cumulative knowledge

Exploiting existing representations implies tapping an enormous domain, coextensive with human understanding and knowledge, and endowed with its own dynamics of piecewise and cumulative learning. The worth of Clark and Thornton's proposal depends on the relative importance of this dynamics and of the bottom-up mechanism they come to complement. Radical restructuring of theories and patterns of retrieval from long-term memory are discussed in the context of such an evaluation.