noahfor

"Try to take the power set of the universal set. You will find that the universal set must be a member of itself and not a member of itself

Russell does use the Russell set and hierarchy to solve this problem."

I understand the contradiction of russell set, but not of the universal set. Why must the universal set not be a member of itself. How does russell use the russell set to solve the problem. I understnd the theory of types, the hierarchy, but not why russell's set is needed to solve the problem. I also understand the contradiction that the power set must be bigger and the same size as universal set but not the contradiction noted above. Thanks.