The paper discusses the role of knowledge in critical thinking, i.e. a controversial issue of whether critical thinking is general or subject-dependant ability. Analyzed are basic assumptions of the authors who maintain the view of the generality of critical thinking, and those who defend the view that critical thinking is subject dependant, as well as their theoretical and practical arguments in favor of their views. The problem of generality of critical thinking is analyzed on three levels: conceptual (whether it is conceptually possible to speak about critical thinking outside a particular subject context); epistemological (whether the epistemological nature of the ability and skill of critical thinking differs in different domains of human knowledge) and practical (practical implications related to developing the most adequate approach to enhance critical thinking). The outcomes of the analysis suggest that critical thinking has both a general and a subject-dependant components, whose contents require further elaboration based on theoretical and empirical research. Educational implications of the analysis indicate that it is necessary to carefully devise the connection between the desired skills and teaching contents in the curricula which aim at enhancing critical thinking. .