The next attribute is infallibility.
Certainty objectively considered is the impossibility of error in a given case. Infallibility also, considered in itself, is the impossibility of error in every case within the sphere to which that infallibility extends. This attribute is essentially necessary to the church, but before we enter upon
its vindication we will say a word about its nature, the subject in whom it resides, the object it embraces, and the mode of exercising it. The nature of the infallibility claimed by the church does not consist in a new inspiration: because inspiration implies an interior revelation of an idea not previously revealed or known. Now, this does not occur, and is not necessary, in order that the church may fulfil its office. The revelation of the whole gnosis respecting God, the cosmos, and their mutual relations in time and in eternity, was made by the Theanthropos in the beginning. The church carries it in her mind, heart, and life, as she traverses centuries and generations. But as all the particular principles constituting that gnosis are not all distinctly and explicitly formulated and set in human language, so it becomes the office of the church from time to time to formulate one of those principles. In this she is assisted by the Theanthropos in such a manner that she may infallibly express her mind in the new formula she utters. Again, an error may arise against the revealed gnosis she carries in her mind. Then it is her office to proclaim what her mind is upon the subject, and condemn whatever may be contrary to it. Again, she is assisted by the Theanthropos in such a manner as to effect both these things infallibly. Infallibility in the present case, therefore, may be defined a permanent assistance of the Theanthropos preserving the church from falling into error in the exercise of her office.
The object of this attribute is limited to these three:
1. She is infallible in teaching and defining all theoretical doctrines contained in the revelation, be it written or not, but handed down socially from the beginning.
2. In all doctrines having reference to morality.
3. In the choice and determination of the external means of embodying that doctrine, theoretical or practical; whether the external means which embodies the doctrine be used by the church, or, used by others, must be judged by the church.
This last object of infallibility is so absolutely necessary that without it the other two would become nugatory and fictitious. If, in propounding a doctrine, the church could err in fixing upon such objective expressions of language as would infallibly exhibit her mind, men could never be assured whether the church had expressed herself correctly or not, and could never, consequently, be certain of her meaning. Likewise, if the church could err in teaching whether such and such expression of language, intended to embody a doctrine, contains an error or a truth, men would be left in doubt whether to embrace or reject it, and could never, in embracing it, be absolutely certain whether they were holding a revealed doctrine or a falsehood.
From this it follows that: First, the church is not infallible in things belonging exclusively to natural sciences, and in no way connected with revelation; second, she is not infallible in reference to historical facts, and much less in reference to personal facts, unless these are connected with dogma. The subjects in whom this attribute resides are the following:
1. The Supreme Pontiff, the head of the hierarchy, who, independent of the rest, enjoys this attribute, in reference to all the objects above explained. Because, by the interior organism of the church, as we shall see, he is made the source of all authority in teaching and governing.