Constructing the Individual Knower

For over 20 years, Ernst von Glasersfeld has eloquently and consistently described a theoretical model of the individual knower. In doing so, he has become one of the best-known contemporary educational theorists, particularly among the mathematics education community.' In addition, as he states in the preface to his newest book, the name he gave to his approach, "radical constructivism," has become a catch word among educators. Today it seems everyone is a constructivist and many attach the descriptor radical to their orientation. However, as with any popular movement, there are many interpretations, many critiques, and much passion associated with radical constructivism. Glasersfeld 2 sees this volume as an opportunity to tell the whole story, or as he says, "to lay out the main constructivist ideas as I see them" (p. xiii). Glasersfeld begins by offering us the opportunity to glimpse his past, particularly those parts that he sees as having influenced his development. Chapter 1, with the playfully Vygotskian title "Language and Thoughtful People," is an autobiographical journey toward his development of radical constructivism. We learn of his European upbringing with multiple languages (German, English, Italian, and French) and how he began to realize that no one language could claim a hold on universal truth. We also learn that Glasersfeld' s formal education ended after one