 Whatever the inconveniences of type theory, contradictions such as [the Russell paradox] show clearly enough that the previous naive logic needs reforming.…There have been other proposals to the same end—one of them coeval with the theory of types. [Quine cites Zermelo 1908.] But a striking circumstance is that none of these proposals, type theory included, has any intuitive foundation. None has the backing of common sense. Common sense is bankrupt, for it wound up in contradiction. (Quine 1951: 153)