The term 'constructivism' refers to a range of epistemological views which share the idea that scientific knowledge, and knowledge in general, should be understood as resulting from a process of human construction. Constructivists consider knowledge to be a product of 'assembling better instruments for prediction and control of the environment' (Rorty 1998a: 76), rather than a representation of the intrinsic nature of reality (cf. Goodman 1978; Rorty 1980). Having no means at our disposal for comparing our descriptions of reality with the mind-independent version of it, we are thrown back on our man-made perspectives and vocabularies of perceiving and describing the world, indissolubly bound to our own interests and needs.
'Facts are creatures of their descriptions' according to Goodman (1987:81). Since there are many different perspectives from which we can describe the world, every situation can be described, according to Goodman, in many different correct ('right') ways. Or, as Rorty states, we can have recourse to many different vocabularies for description. For example, the world of 'molecules' differs from that of 'values'. In addition to this, those different descriptions cannot be considered as two partial descriptions of one and the same 'external' reality. In fact, no description can be reduced to 'the' reality (Rorty 1989:11f.). In this sense, constructivists assume that there must be many worlds, each of them an artefact of its own description (Goodman 1987).
In the absence of any mind-independent access to external reality, we cannot bypass our dependence on vocabularies and perspectives. Consequently, as vocabularies and perspectives are of human origin, every description of reality must be considered 'conventional' (Goodman 1987). Not surprisingly, this leads many constructivists to the study of either individual or social processes of knowledge development, sometimes equating these processes with constructivist epistemology itself.
One tradition, reasoning from the genetic epistemology of Piaget, investigates the psychological and biological prerequisites of knowledge.