The main goal of the article is to argue for admissibility of substitution of coreferential proper names in belief contexts which generally has not been allowed in the logico-semantic tradition that dates back to the works of G.Frege. The main object of criticism is a so-called principle of disquotation, as formulated by S.Kripke, which conditions the prohibition of the aforementioned substitution and which is accepted within the Fregean tradition. Some related issues associated with the works of R.Carnap, W.V.O.Quine, and N.Salmon are addressed.