 Quine (1937) and (1967) similarly provide another untyped method (in letter if not in spirit) of blocking Russell’s paradox, and one that is rife with interesting anomalies. Quine’s basic idea is to introduce a stratified comprehension axiom. In effect, the axiom blocks circularity by introducing a hierarchy (or stratification) that is similar to type theory in some ways, and dissimilar in others. (Details can be found in the entry on  Quine’s New Foundations.)  