I was puzzled by the statement that he didn't learn much from the classes he took in formal logic. >(Consider "I don't know if I learned anything from them. "

I was puzzled by the statement that he didn't learn much from the classes he took in formal logic. >(Consider "I don't know if I learned anything from them. " Footnote: 1 "In practice formal logic is not much use,..." ) This guy has programmed massive amounts of LISP code, and written books about LISP. How can he say that his training in formal logic didn't take him anywhere?