I disagree that they are infallible, my friend. Who 'gets to say' where the infallible ones end and the fallible ones begin, and by what authority would they get to say it? Any answer would be have to be arbitrary. If you say, because of the men who were there, then we're back to the distinction that Paul made between the message and the messengers. Which one(s) erred? The Second Council of Nicaea (787 AD) erred, for one. These councils have a measure of authority, but only insofar as they agree with Scripture -- in which case, it is a *derived* authority. But the question is always: does Scripture teach this? Because _scripture alone_ is the ultimate authority on all questions of doctrine and life.