Full Idea
One may be of the opinion that no sentence ought to be considered as a truth of logic if, no matter how it is interpreted, it asserts that there are sets of certain sorts.
Gist of Idea
A sentence can't be a truth of logic if it asserts the existence of certain sets
Source
George Boolos (On Second-Order Logic [1975], p.44)
Book Reference
Boolos,George: 'Logic, Logic and Logic' [Harvard 1999], p.516
A Reaction
My intuition is that in no way should any proper logic assert the existence of anything at all. Presumably interpretations can assert the existence of numbers or sets, but we should be able to identify something which is 'pure' logic. Natural deduction?