 The prohibition of self-application together with the use of “flat” sequences of arguments means that infinitely many predicate functors are needed to ensure the elimination of bound variables from all formulas of FOL. To explain the problem quickly: a permutation of a pair of elements that are arbitrarily far apart cannot be ensured otherwise. Just as combinators may be divided into groups based on their effect, Quine was able to select predicate functors that can be grouped together naturally based on their effects. Indeed, the groups of predicate functors are similar to classes of combinators, though Quine’s labels are often sublime. In order to give a concrete example of this alternative approach, we outline a slightly modified version of a set of predicate functors from Quine (1981).