The aim of this paper is to detect the necessary and sufficient means for the construction of a proposition qualified by Wittgenstein's Tractatus (6.54) as being of the ladder-type and nonsensical. Using some concepts from recursion theory, by translating the inconsistency of unrestricted comprehension schema into an inconsistency with the predicate "satisfiable" (Sat), and by testing the behavior of Sat in two different formal languages, we show that the negation and a concept of self-reference are minimum required for a ladder-type proposition. Some logical consequences of this fact are drawn. Firstly, we mention some ladder-type propositions for Peano Arithmetic and the way they can be consistently managed with respect to this theory. And secondly, under the same label of “ladder-type proposition” we also consider a special case of self-reference, called retorsion, directly connected to Heidegger’s paradox of thematization: if the meaning of the originary truth (ursprüngliche Wahrheit) reveals itself non-thematically, how then can it be thematized? As I shall argue, both great projects of the destruction of metaphysics (Wittgenstein’s and Heidegger’s), finishing paradoxically, can regain their full coherence only by an adequate management of all ladder-type propositions.