Introduction. Philosophical analyses of theoretical principles underlying these sub-domains reveal philosophy of information as underlying meta-theory of information science.
Method. Conceptual research on the knowledge sub-domains in information science and philosophy and analysis of their mutual connection.
Analysis. Similarities between conceptual cores and research questions of the two fields have been investigated. The consequent methods and knowledge domains of philosophy of information have been studied.
Results. As the underlying theory, philosophy of information discovers philosophical questions in all of the information sub-domains studied. In information retrieval, it studies ontological and epistemological. Knowledge organization implements philosophy of language. Theories of information management actualize classical epistemological issues in the context of organizational knowledge. Studies of information behaviour benefit from argumentation theory. Philosophical analyses may possibly investigate how the concrete rules of bibliometric models influence conceptions and evaluations of knowledge. The sub-domain of information literacy is significantly compatible with philosophical conceptions and techniques of critical thinking.
Conclusions. As underlying and unifying theory of information science, philosophy of information implements advanced abilities of critical thinking in the sub-domains, with respect to the role that information technology and the resulting knowledge structures, codes, languages and systems might have for the development of mind and world.