The principle of complementarity in physics can be generalized and extended to information studies. It helps explain the dilemma faced by information studies today. The prevailing endeavor that going beyond the limitation of formal theories and to develop a unified theory of information falls in the dilemma which is structurally homologous to the dilemmas in quantum physics. The dilemma is caused by an epistemological paradox called assignment paradox. The paradox can be removed through generalized complementarity. It means that the concept (...) of information embodying in different theoretical contexts are different phenomenon. They are complementary to each other. The analysis brings bad news to methodologically reductionism and fundamentalism but good news to transdisciplinary approach. (shrink)