ラッセルのパラドックス
Russell's Paradox has shown that naive set theory, based on an unrestricted comprehension scheme, is contradictory. Note that there is a similarity between the construction of "T" and the set in Russell's paradox. Therefore, depending on how we modify the axiom scheme of comprehension in order to avoid Russell's paradox, arguments such as the non-existence of a set of all sets may or may not remain valid.