Constructivism and the problem of reality

The problem of how we know reality constrains theories of cognitive development. A constructivist model of knowing is discussed in which reality is known through acting on it and coordinating actions through interaction with others. It is argued that explaining reasoning as the manipulation of visual-spatial mental representation is based on untenable epistemological assumptions. Instead, it is proposed that reasoning involves children's operational understanding of key terms in problems and the composition of these operations, rather than applying logical rules or manipulating mental models. This approach is illustrated with research on class inclusion and transitive reasoning.