How Infallibility Works

Some people think papal infallibility is crazy talk, but it isn't magic nor is it nuts. It is actually very simple. And it isn't the encyclical or the bull that is, or is not, considered infallible. It is the teaching within the document, whatever that document might be.

Look, the Pope is the Pope whether he arrives at a location in the Popemobile or in a VW bug. Doesn't matter. The vehicle isn't the important thing, it's the person in the vehicle.

Same with teachings. While certain types of documents are associated with a certain level of authority (e.g., apostolic constitutions are considered the document with the highest level of authority within the Ordinary Infallible Magisterium), it is the content of the document that is considered infallible, not necessarily the document itself.

So, changes to the liturgy (e.g., raising a person to the altar of sainthood) are infallible teachings. But an infallibly true statement can be made in ANY kind of document. Heck, I can make an infallibly true statement in this post... watch me, "God is one God in three distinct Persons." There.

By echoing the constant teaching of the Church, I just made an infallibly true statement. That is all the Pope does when he speaks infallibly. He simply teaches what the Church has always taught.  That is literally all there is to papal infallibility. Nothing more. 

That's all the Pope does when he promulgates in infallible teaching - he just states the constant teaching of the Church. Now, in some cases, this teaching is not - for whatever reason - very well known. Worse, not only is it the case that not everyone is fully aware that something is a constant teaching of the Church, but in a few cases, some Catholics are actually actively opposed to a constant teaching of the Church. In those cases, the Pope has to promulgate the teaching with a very high level of authority. That's an exercise of the Extraordinary Infallible Magisterium.

But sometimes, there isn't active opposition, there is just confusion or lack of clarity, or certainty, etc. The lack of certainty by a large swath of Catholics doesn't merit a high level of forcefulness, so the Pope just puts the constant teaching out in a vehicle that is associated with a lower level of assertiveness. This is the Ordinary Infallible Magisterium.

The lower level of assertiveness does not mean the teaching is "less" true, it just means the Pope feels we only need a gentle reminder. For these teaching, we don't need a slap across the face to get our attention. Various documents within the Ordinary Magisterium may be vehicles for various teachings of the Church - while some teachings certainly derive from others, all of these constant teachings are equally true, all are infallibly correct, all are co-equal in these respects. The document the teaching is promulgated in shows us how the Pope assesses our grasp of the Faith. The more assertive the document, the more obvious it is that the Pope wants us to pay close attention to this teaching. The more assertive the document, the more important it is to our life of faith. Thus, since liturgy and sacraments are central to the life of faith, those are always put out with a very high level of Ordinary Magisterial authority - apostolic constitutions. Other teachings are equally true, but perhaps not as central to every-day life, so a lesser vehicle is used. 

That is the role of the various kinds of documents, why we have several kinds. Hopefully, this clarifies the understanding of infallible teachings and the various documents that transport them safely to our doorsteps.