Ever since we wrote a paper on the constructivist theory of knowledge for the Journal, fifteen years ago, chemists and chemical educators have asked: Do you really believe in the constructivist theory? The answer is: Yes. As we talk to colleagues we have become convinced that the source of their concern about this theory is the version to which they have been exposed. As we note in this paper, even critics of this theory argue “that there is a very broad and loose sense in which all of us these days are constructivists.… ” This paper outlines the different forms of the constructivist theory and describes a version proposed by the clinical psychologist, George Kelly, that avoids some of the controversial elements of the radical constructivist theory developed as an extension of the work of Jean Piaget.

Constructivism has become an important referent for research and practice in science education. A variety of more or less divergent forms of constructivism have developed: discussion between these is occasionally heated. Six such forms are briefly described in order to provide an overview of the held of constructivist theory. A scheme for characterising constructivist writing on the basis of its relative emphasis on (a) personal versus social construction of knowledge and (b) objectivist versus relativist views of the nature of science is suggested. Issues of theory creation and reflexivity, central to constructivist practice, are discussed. It is suggested that debate about the “best” form of constructivism is counterproductive. A more powerful approach to epistemology is that described by Feyerabend, the holding in dialectical tension of a variety of incompatible perspectives.