 Building explicit hierarchies is sufficient to avoid circularity, and thus sufficient to block the standard paradoxes of self-reference. However, there also exist paradoxes such as Yablo’s that do not rely on circularity and self-reference. Such paradoxes can also be blocked by a hierarchy approach, but it is necessary to further require the hierarchy to be well-founded, that is, to have a lowest level. Otherwise, the paradoxes of non-wellfoundedness can still be formulated. For instance, Yablo’s paradox may be formalised in a descending hierarchy of languages. A descending hierarchy of languages consists of languages \(L_0, L_{-1}, L_{-2},\ldots\) where each language \(L_{-i}\) has a truth predicate that only applies to the sentences of the languages \(L_{-j}, j\gt i\).  Similarly, a set-theoretic paradox of non-wellfoundedness may be formulated in a type theory allowing negative types. The conclusion drawn is that a stratification of the universe is not itself sufficient to avoid all paradoxes—the stratification also has to be well-founded. 