about the meaning of “invincible ignorance” in Catholic parlance. But it is true that I didn’t use the phrase in accordance with Catholic usage: I certainly would not concede that Hitchens has exercised moral diligence in trying to learn about his subject. Does my adherence to the popular usage of the phrase make any of his gross errors correct? If this is the best he can come up with, his case was every bit as weak as I thought. I am no authority on Catholicism, nor would I claim to be. Hitchens flatters himself if he thinks it necessary to be an authority to see through him.