Methodological Status of Paraphrase in Selected Arguments of Tadeusz Kotarbiński and Kazimierz Ajdukiewicz

Both Tadeusz Kotarbiński and Kazimierz Ajdukiewicz referred in their philosophical inquiries to the so-called arguments from paraphrase. These arguments, assert as one of the premises the statement that there is a paraphrastic relation holding between some expressions. This type of argumentation is quite common in analytic philosophy, perhaps even essential for it. Meanwhile, the methodological status of this operation and relation still needs reflection. In this chapter, two arguments from paraphrase are discussed: Kotarbiński’s argument for the methodological thesis of reism (in Marian Przełęcki’s interpretation) and Ajdukiewicz’s argument against transcendental idealism. We will show the place of paraphrastic premises in the structure of selected philosophical arguments. We will reconstruct an assumed meaning of ‘the relation of paraphrase’ and present the reasons supporting those premises. We will discuss the argument for the methodological thesis of reism which is based upon a weak formulation of the semantic thesis and the methodological principle of ontological parsimony. A reist should be able to formulate a reistic theory of paraphrase, and in particular, he should not assume non-reistic expressions to be primarily meaningful. As it seems, his theory should match non-reistic and reistic sentences, on the sole basis of their syntactic structure. As stated by Kotarbiński himself, justification supporting the semantic thesis of reism is naively intuitive and based on common induction. Ajdukiewicz tries to reformulate the position of idealism, expressed in the thesis of idealism. Therefore, he establishes a correlation between expressions belonging to the idealist language and expressions belonging to the language of semantic epistemology. By using metalogical theorems, he demonstrates the falsehood of the thesis of idealism in its semantic formulation. However, the principles of the procedure of semantic paraphrase used by Ajdukiewicz are not—and probably cannot be—strictly defined what undermines the validity of his account.