A current debate within the cognitive development literature addresses
how best to characterize conceptual change, Within one proposal, deve
lopment primarily consists of a series of radical conceptual shifts or
restructurings in which the most current understanding is inexplicabl
e within (incommensurate with) prior conceptual structure. Alternative
ly, development is discussed as more gradual enrichment of multiple ex
isting early explanatory systems, allowing for commensuarability over
time and change. This paper examines the literature in this debate wit
h specific focus on naive biological understanding, and discusses a se
ries of studies on preschoolers' inductive inferences across biologica
l and non-biological kinds. Children were taught a series of biologica
l properties for a human being (e.g. eating, sleeping etc.), and asked
to generalize these properties to both biological (e.g. dogs, worms)
and non-biological kinds (e.g. clouds, tables). The results of these s
tudies support the gradual enrichment proposal. Specifically, 4-year-o
lds seem to possess a limited, but coherent and independent biological
theory which may form the basis of mature understanding of biological
kinds. These results are discussed in terms of multiple explanatory s
ystems which both preschoolers and adults can employ across developmen
t to effectively guide their decisions within a given domain. (C) 1998
Elsevier Science B.V.