Context: Despite many obvious advantages (radical) constructivism has over other philosophies it has failed to become a mainstream philosophy that is widely taught and discussed. Problem: What are the reasons for this failure? Can we identify issues that make it difficult for scholars to accept and even embrace radical constructivist ideas? What is the best way to characterize, explain, and eventually refute objections? Method: By collecting articles from both proponents and opponents of radical constructivism the editors of the special issue (...) tried to present a range of answers to these questions. Results: Some problems are due to known objections to radical constructivism, in particular the idea that being responsible for one’s own constructions opens doors to a “whatever” attitude. Another important insight is that constructivism seems to resemble a river delta with ever branching new sub-disciplines that become increasingly incompatible with each other. Implications: The insights gained from the contributions may lead to a re-orientation of (radical) constructivism that will include less misunderstandings among its critics and to a higher acceptance in the academic community. (shrink)