In class, we discussed Ernst von Glasersfeld's agnostic position in regard to metaphysics. However, there are a number of instances in his Introduction to Radical Constructivism at which he seems to acknowledge an external reality, or his argument implies the existence of an external reality. First, he seems to refer favorably to Piaget's theory of evolutionary epistemology, which involves an external reality that eliminates ideas that do not "fit." Given this acknowledgment alone, von Glasersfeld's epistemology does involve an ontological affirmation of external reality. His argument might still assert substantial limits on one's access to such a reality. However, his inability to identify the extent of reality that one cannot know complicates this assertion.

Later, von Glasersfeld discusses the way in which a magician can trick an audience into constructing a particular idea of reality that is not true. This ability to recognize the falsehood of a construction indicates both that human experience does provide access to a certain degree of objectivity, and that objectivity operates to a certain degree in the realm of experience. Knowledge of such objectivity seems to me to undermine radical constructivism.

In regard to von Glasersfeld's alleged separation of epistemology and metaphysics, I cannot conceive of a metaphysical statement that does not invoke epistemology, but is it possible to make an epistemological claim without invoking metaphysics? Epistemology obviously involves an ontology in regard to what can be known, but must it claim anything about the existence of what cannot be known?