Critical Thinking (CT) has a peculiar content, though it stems from informal logic. Moreover, CT also has several presuppositions, all of which are peculiar to CT. A significant number of these presuppositions are of a nonlogical character. Yet in order to continue the logical analysis in a sound way, it is crucial to take these presuppositions into account. In this paper, these presuppositions and preconditions will be set forth together with the reasons for identifying them. The paper is restricted to (...) the presuppositions which are not found in informal logic. Hence, essentially the preconditions regarding the debate and the preconditions regarding the abstraction of the argument will be the topics of consideration. The preconditions regarding the debate consist of pragmatic and semantic preconditions. In contrast, the preconditions regarding the abstraction of the argument are the principle of charity, the principle of loyalty, and linguistic and contextual awareness, which are all crucial for the application of these two principles. Moreover, for CT, a rational subject has a key importance, even if their rationality comes in degrees. The degree of rationality of such a rational subject is also considered, and the degree in question necessary for a sound argumentation is expressed in terms of a minimal degree of rationality. Furthermore, a problem set forth by Suvar Köseraif is taken into account. Moreover, it is asserted that this problem is essentially related to the abstraction of the argument from the context and especially related to linguistic and contextual awareness. (shrink)