Knowledge Acquisition: Enrichment or Conceptual Change?
Susan Carey Massachusetts Institute of Technology
Several contributors to this volume develop the theme that learning requires the support of innate representations. Further, they provide data that reveal the nature of innate representations that guide cognitive development (see especially chapters 1, 2, and 5). Spelke (chapter 5) defends a stronger thesis: The initial representations of physical objects that guide infants' object perception and infants' reasoning about objects remain the core of the adult conception of objects. Spelke's thesis is stronger because the existence of innate representations need not preclude subsequent change or replacement of these beginning points of development. Her argument involves demonstrating that infants as young as 2 1/2 to 4 months expect objects to move on continuous paths and that they know that one object cannot pass through another. She concludes by making a good case that these principles (spatiotemporal continuity and solidity) are central to the adult conception of objects as well. In the case of the concept of a physical object, cognitive development consists of enrichment of our very early concept, not the radical change Piaget posited.
I do not (at least not yet) challenge Spelke's claim concerning the continuity over human development of our conception of physical objects. However, Spelke implies that the history of the concept of an object is typical of all concepts that are part of intuitive adult physical reasoning. Further, she states that in at least one crucial respect, the acquisition of commonsense physical knowledge differs from the acquisition of scientific knowledge: The development of scientific knowledge involves radical conceptual change. Intuitive conceptions, in contrast, are constrained by innate principles that determine the entities of the mentally represented world, thus determining the entities about which we learn, leading to entrenchment of the initial concepts and