Whenever someone does not agree with a teaching of the Church, they often express a hope that when a new Pope gets in, he might change it so that it might agree with their opinion. Of course, this would be an understandable possibility in a Democracy like our own where our own leaders are elected and change could become a frequent occurrence.
But, even in our own American context there is the authority of the Constitution to contend with. Within this constitutional context, there are two schools of thought. One is the Originalist interpretation which seeks to stay very close to the text and the understanding that the framers of the Constitution had concerning the words that they used. The other school is the “Living Constitution” interpretation that seeks to fit new issues into the broad concerns and principles enshrined by the framers.
The Church and Her teaching are very different. Because the teaching is revealed to us by God, it has a timeless meaning and cannot be altered or changed. Our understanding of that teaching, however, can develop over time, especially when new concepts are introduced by the secular world that lets us see elements in God’s teaching in a new way. St. Vincent of Lerins, a medieval scholar and saint, compared the development of dogma to a human person. When one is a baby, one is all potential waiting to happen. But when that child reaches adulthood and then old age, they are very different and much more developed; but (and this is a big but) they are still the same person. They do not suddenly become someone else. Their development is linear and grows in them organically.
When we consider the way that Church Teaching may develop, we can completely abandon any idea of the teaching contradicting itself. If a teaching on any moral theme were to change so completely that it means the exact opposite, this could never be a true development. Like the growth of a human person, or an animal or a plant, it is organic and it cannot change into something else.
So, when people express a desire that the Pope or a Council change a long-held teaching of the Church, what they are asking is the impossible. While the teaching can be better expressed or seen in a new way by the people of a time and place, it cannot be a contradiction of the original formulation of that teaching. The Pope, therefore, cannot change a long-held teaching in the Magisterium of the Church. Nor, unlike the American Constitution, can the Bible be amended.
The cause of this is our understanding of the authorship of Revelation. Though God uses human beings and human concepts as His instruments, He, God Himself, is the author of Scripture and the Guide of Tradition. To change a teaching is to say that God was wrong or that He mislead the Church for centuries. This is impossible if we believe that God is the true author of the Teaching of the Church.
There are, however, disciplines of the Church that a Pope can change. For instance, when Mass was in Latin. God never said that He wanted us to use Latin instead of the common language of the people (Vulgate). So, at the Second Vatican Council, the Council Fathers and the Pope changed the language of the Liturgy so that it may be said in the common language of each church. The Law was man-made and could be changed.
A council or Pope cannot change the Ten Commandments or the Eight Beatitudes. These come directly from God and are to be held forever. But our understanding of the implications of the Commandments or Beatitudes can develop as long as the essence of them are not diluted or changed.
Moreover, there are some teachings that are in a kind of ‘gray area’. For instance, is a celibate priesthood a law from God or from man? You can have theologians argue on both sides of that issue.
The problem is that our news media hasn’t the foggiest idea what the distinction between divine and human law actually means. So, if you take your lead from the newspapers and newsrooms, you are likely to wonder why the Pope can’t change particular practices in the Church. He does not have the power to change something that comes from God Himself.
To sum up: Church Teaching that is divinely revealed can develop, but cannot change. While this is hard to accept by those of us trained to think in a Democracy, it is a fact of life and of the Faith of the Church.