 The CH and the AC are central questions of set theory and subjects of continuing debate. While the AC is mostly accepted as an axiom, and is part of the ZFC axiom system, the CH is widely considered an open problem. There are even suggestions (e.g., Feferman 1999) that it cannot be solved by any axiom system with the kind of general acceptance that ZFC has. The formalist position in the foundations of mathematics goes further and maintains that the question, what the truth value of CH is, is meaningless. Both CH and its negation are consistent with ZFC, assuming ZFC itself is consistent. According to the formalist position the status of CH has been solved with this. The semantics of second-order logic depending on these hard questions of set theory puts second-order logic into the same “basket” with set theory. Criticism of set theory becomes criticism of second-order logic and vice versa.