  It is a bit unclear that the “notions” of membership that Tarski talks about are notions in the sense introduced by him earlier in the lecture. They do not “occur” in any type, given the standard formulations of the theory of types (even in formulations in which a sign for membership is used), for they are relations among objects of different types, which do not occur in a non-cumulative hierarchy. But Tarski is perhaps thinking of some non-standard, cumulative type hierarchy. Under a suitable expansion of the concept of a notion, the notions of membership Tarski has in mind will indeed be invariant under permutations of any universe, and hence logical; and the sign or signs for these notions of membership will be Tarskian logical constants. On the other hand, as pointed out above, membership as a relation over the domain of individuals and sets will not be a logical notion in that domain, and hence the sign for this concept of membership will not be a Tarskian logical constant. Thus, interestingly, Tarski’s definition of the concept of logical constant respects in a sense his early relativistic view in the paper on logical consequence. Tarski describes the situation in the following passage: