Note on a paradox
Robert L. Stanley · Journal of Symbolic Logic · 1953
The usual logical paradoxes, which stem from Russell's class R0 (i.e., and its relatives R1, R2, and so on (i.e., , , and so on, correspondingly), are contradictions (Ri ϵ Ri) ≡ ~(Ri ϵ Ri), derivable under unrestricted rules of inference. No contradiction appears to obtain.