Radical constructivism
Radical constructivism adds a second principle to trivial constructivism (von Glasersfeld, 1990) :Coming to know is a process of dynamic adaptation towards viable interpretations of experience. The knower does not necessarily construct knowledge of a "real" world.
We do all create our own realities. Radical constructivism does not deny an objective reality, but simply states that we have no way of knowing what that reality might be. Mental constructs, constructed from past experience, help to impose order on one's flow of continuing experience. However, when they fail to work, because of external or internal constraints, thus causing a problem, the constructs change to try and accommodate the new experience.
Within the constraints that limit our construction there is room for an infinity of alternatives. "Truth" in traditional epistemologies is replaced by "viability", bounded by social and physical constraints. The large diversity of flourishing public opinions in today's society on nearly every conceivable topic is evidence that a range of viable constructs are possible to allow survival and growth in the world.
From a radical constructivist perspective, communication need not involve identically shared meanings between participants. It is sufficient for their meanings to be compatible (Hardy and Taylor, 1997). If neither of the parties does anything completely unexpected to the other, then their illusions of identically shared meaning are maintained (von Glasersfeld, 1990).
The emphasis here is still clearly on the individual learner as a constructor. Neither trivial nor radical constructivism look closely at the extent to which the human environment affects learning: it is regarded as part of the total environment. These issues are focussed on in more detail by social,
cultural and critical.
References
Dougiamas, M. (1998). A journey into Constructivism, http://dougiamas.com/writing/constructivism.html
Hardy and Taylor (1997), Von Glasersfeld's Radical Constructivism: A Critical Review, Science and Education, 6, pp 135-150, Kluwer
Von Glasersfeld, E. (1990) An exposition of constructivism: Why some like it radical. In R.B. Davis, C.A. Maher and N. Noddings (Eds), Constructivist views on the teaching and learning of mathematics (pp 19-29). Reston, Virginia: National Council of Teachers of Mathematics.