It seems that you don’t get it. Said just demonstrated that even if C exists it wouldn’t imply a universally compelling argument.
So what? Neither the existence or non existence of a Criterion of Truth that is persuasive to our minds is implied by the (non) existence of universally compelling arguments. The issue of universally compelling arguments is a red herring.
So what? Neither the existence or non existence of a Criterion of Truth that is persuasive to our minds is implied by the (non) existence of universally compelling arguments. The issue of universally compelling arguments is a red herring.