Here is an arguement that you'll not find the Roman Catholic Church using often:
If the Pope (Bishop) of Rome is infallible, then Pope Leo the Great's tome concerning infallibility must be infallible. Yet it was an arguement against infallibility.
It's like trying to reconcile error with error. It does not work.
Very little, and often nothing, of what any pope speaks or writes is infallible. To be infallible a statement must be made in consensus of all the bishops who are in communion with Rome on matters of faith and morals and it should make clear that the pope intends it to come from the Chair of Peter and not from him as a private theologian. I don't know enough to say the Leo the Great's book is infallible, and I don't know enough to say that it contradicts the doctrine of infallibility rightly understood; do you?
"It's like trying to reconcile error with error. It does not work."
Please, let's not start confusing ourselves with the facts.
:)
While not really germaine to my comments...the document which you refer to is not an "ex-Cathedra" statement and therefore doesn't pertain to the infallibility issue.
I'm really very confused as to why you threw that out there......