Within Catholic circles, there is a debate as to whether canonization of saints is infallible. This is particularly important for the SSPX and other groups that, while seeking some agreement with the Vatican, reject the canonizations of John Paul II, Paul VI, Teresa of Calcutta, and Josemaría Escrivá (founder of Opus Dei).
Interestingly, many Catholic theologians have argued that canonizations are protected from theological error, so in a secondary sense, they are infallible (the concept of the “secondary objects of infallibility”). In his study of the origins and early development of papal infallibility, Donald S. Prudlo discusses Aquinas’ reasoning to support this teaching:
For Thomas, the pope is unable to err in canonization for three reasons: (1) he makes a thorough investigation into holiness of life, (2) this is confirmed by the testimony of miracles, and (3) the Holy Spirit leads him (for Thomas, the clincher). When a pope elevates a saint, he proclaims that the saint is in heaven. The pope asks the faithful to give honor to the saint, which means that the faithful are making a quasi-profession of faith in the glory of the saint. Since, as Thomas says, no damnable error can exist in the church and since it would be a damnable error or the faithful to honor a saint in hell, therefore no canonized saint can be in hell. Or Thomas the church, then, is not “liable to error” in this case. Thomas would say that the canonization of a saint involves a declaration that relates materially to a dogma of the church. Thomas articulated, for the first time, the infallibility of the papacy in the glorification of saints. For him, though, the definition of dogma is a very strict business. Since nothing without at least in seed in the scriptures can be an article of faith, Thomas would not call infallibility in canonization in itself a dogma. He makes a rather fine distinction. Each canonization was infallible considered in itself, because no damnable error can exist in the church, but since it cannot be absolutely derived from the scriptures, the doctrine of the infallibility of the pope in canonization is a matter of pious belief only. Later thinkers would follow Thomas’s reasoning but would not be as reticent in their thoughts on the binding authority of the doctrine. (Donald S. Prudlo, Certain Sainthood: Canonization and the Origins of Papal Infallibility in the Medieval Church [Ithaca, N.Y.: Cornell University Press, 2015], 128-29)
In an Appendix, “Thomas Aquinas, Quodlibet IX, q. 8,” Prudlo reproduces Aquinas’ own comments on this issue:
Title 1
Whether all saints who are canonized by the Church are in glory or whether some are in hell.
Title 2
And it seems that some are able to be in hell among those who are canonized by the Church.
Argument 1
No one is able to be certain about the condition of anyone, as one is of himself, “For who among men knows the things of a man save the spirit of man which is in hell?” as 1 Corinthians 2:11 has it. But man is not able to be certain about his own condition, as to whether he be in a state of salvation for as Sirach 9:1 says, “Love from hatred man cannot tell.” Therefore how much less can the Pope know, therefore he is able to err in canonization.
Argument 2
Furthermore, whoever relies upon a fallible medium in judging is able to err. But the church in canonizing saints relies upon human testimony, when she inquires of witnesses regarding lie and miracles. Therefore, since the testimony of humans may be fallible, it seems that the church is able to err in canonizing saints.
Contra 1
On the contrary, in the church there is not able to be a damnable error. But it would be a damnable error if she would venerate a saint who was a sinner, because anyone knowing their sin might believe the church to be false and if this were to happen, they might be led into error. Therefore the church is not able to err in such things.
Contra 2
Further, Augustine says in a letter to Jerome that if there is admitted to be any lie in canonical scripture our faith will waver, since it depends on canonical scripture. But we are bound to believe that which is in the holy scriptures, so also that which is commonly determined by the church; therefore heretics are judged who believe things contrary to the determinations of the Councils. Therefore the universal judgment of the church is not able to err, and thus the same result as above.
Response
It must be said, that something can be judged to be possible when considered in itself, which in relation to something outside itself is found to be impossible. Therefore I say that the judgment of those who rule the church is able to err in anything, if they are considered in their persons. If, in truth, divine providence is considered—by which the Holy Spirit directs his Church, so that she might not err, as He Himself promised in John 10, that the Spirit was coming to teach them all truth, namely about those things necessary for salvation—then it is certain that it is impossible for the judgment of the universal church to err in those things which pertain to the faith. Wherefore how much more certain is the determination of the Pope, to whom it pertains to pronounce on faith, than in the wisdom of any other man in their scriptural opinions; it is read when Caiaphas—though wicked—nevertheless prophesied because he was high priest, though he did not know it (that is, he did not know it himself) as John 11:51 has it. Truly in other determinations which pertain to particular facts, as is done with property, or crimes, or other such things, it is possible for the church to err on account of false testimony. But truly the canonization of saints is between these two things. Since the honor we pay the saints is in a certain way a profession of faith, i.e., a belief in the glory of the Saints, we must piously believe that in this matter also the judgment of the Church is not liable to error.
Ad 1
To the first is therefore to be said, that the Pontiff—to whom it belongs to canonize saints—is able to certify the condition of any by means of an inquiry into their life and by witnesses to their miracles; and especially by the inspiration of the Holy Spirit, who searches all things, even unto the profundity of God.
Ad 2
To the second is to be said, that Divine Providence preserves the Church assuredly in such things as may be deceived by fallible human testimony. (Ibid., 181-83)
