There are some important notes at the end of this page which I encourage you to read.
The following links are to documents and folders from my Google account, which should be publicly viewable and downloadable—if not, please let me know, and I will do what I can to fix the problem. Do not hesitate to inform me of likely typos either!
On the Credibility of Certain Theologians: https://docs.google.com/document/d/1oH6095Ko-WaAkjSlFl2bcKHtFisd9A52Kr4lj3bGjkM/edit?usp=drivesdk
On Quanta Cura & the Syllabus of Errors: https://docs.google.com/document/d/1CkL7_4kAJnu0elH2DlLxwabL6duF9KIykr1MPEQsb5Q/edit?usp=drivesdk
On Pope Honorius: https://docs.google.com/document/d/15j6LSUlp7FT23opN9bInPCgcmON5JHD6rfAIkLA85D8/edit?usp=drivesdk
On Infallibility and the Universal Ordinary Magisterium: https://docs.google.com/document/d/1kZsm3Ay06BksGZjd7meLI-vv0fNiBpRdqfoRk3g33S0/edit?usp=drivesdk
On the Secondary Objects of Infallibility: https://docs.google.com/document/d/1grMn73kM4yveROeqp_nOR6DyPd310kzU2MisVgiIHTg/edit?usp=drivesdk
Ultramontanist Theologians: https://docs.google.com/document/d/1FgEV4iUn8LtqgynJpujAzRzQ51DzQZMC66zoyD14DMk/edit?usp=drivesdk
Theologians on the Proximate Rule of Faith: https://docs.google.com/document/d/1orAKH6pljjTOijZrIJYbF2d8E2ih08L4jDpf_pt5LQ0/edit?usp=drivesdk
Necessity of Explicit Faith in God: https://docs.google.com/document/d/1uJvcjNdZM3KO8zsIa1Ucy5eQ_eNtIQlFEZffYImCeHU/edit?usp=drivesdk
On the Sacraments & Liturgy: https://docs.google.com/document/d/1tQLjWbr_nobweCzaexCrFrgUiLtoQ0URMg5NALZshFM/edit?usp=drivesdk
Church Fathers on Peter & the Papacy: https://docs.google.com/document/d/16R-GKi-CfsDGs7llNhgWGmYO9S88p9nxbnBaU1b2CPg/edit?usp=drivesdk
Early Ecumenical Councils on Peter & the Papacy: https://docs.google.com/document/d/1xvQ3YdQkufiVhCsxgYpJeX1lrSnpK3QZv-_JaWZNuok/edit?usp=drivesdk
Silence & Speaking the Truth: https://docs.google.com/document/d/1EseedKI79-izIKyKn8ktnn8k2cRxmQLvq3tGehnjvTU/edit?usp=drivesdk
Communicatio in Sacris, Ecumenism, Mixed-marriages, etc, (“Sacred and Profane Communication”): https://docs.google.com/document/d/1ayP6uXzcH06BgzPOU1j-1MVU3Xumd9mkMh25aS_zvq0/edit?usp=drivesdk
On the Catechism of Trent/Roman Catechism: https://docs.google.com/document/d/1LkHq8nKfp7a5OoZeHxDvqetU3XZaosW-xg-aCWzPPH8/edit?usp=drivesdk
Theologians on Church Membership: https://docs.google.com/document/d/1TBaX_kqeKenJ-7zBj_jOKFR2YYKKBJsspDRQs_4ZKDw/edit?usp=drivesdk
Paganism (that Europe has been pagan for a century at least): https://docs.google.com/document/d/1UBWRnDYT4M13KcPKhXeTls2Xc8vlRLb_Cheq1K1jq_U/edit?usp=drivesdk
Forgotten Catholic Quotes: https://docs.google.com/document/d/1musN8qdkfWXWBt0jez-yAoyhP21Ri4JSwTQmOuJ3BCk/edit?usp=drivesdk
The Name “Catholic”: https://docs.google.com/document/d/1SzoL6_5MU8AOPg03EKYs-16uFLy5dJHPLVT321AVfGw/edit?usp=drivesdk
On Scriptural Inerrancy/Interpretation: https://docs.google.com/document/d/1Ojv5U-45D3oaCB1ScMb6kdqL1vcrP6sGwqKKGZ5KTj4/edit?usp=drivesdk
On Peter, the first pope: https://docs.google.com/document/d/1t4ad3DBY6AADSQBVaX6vDQ1fp6J2S8baXYNL6NKBVXg/edit?usp=drivesdk
Papal Heresy Precluded: https://docs.google.com/document/d/1FkyCuknh_fcR5D9_IkaD7vauowl6BIqRvYVWutxFY20/edit?usp=drivesdk
Infallible Safety of the Papal Ordinary Magisterium: https://docs.google.com/document/d/1dGrD0Nk2IpjRhaFLbXIOhMdGTTcOdBRw3BF2YGDbjQA/edit?usp=drivesdk
Popes and Theologians on the Papal Ordinary Magisterium (same quotes as in the preceding document, but without my own commentary and argumentation): https://docs.google.com/document/d/116-7N8-BYlZRz_8jC6DYy8oL1F8_f0E1R6cNk9COBhc/edit?usp=drivesdk
Theologians & Philosophers on Capital Punishment/Death Penalty: https://docs.google.com/document/d/1QIsDA8afVzxDubpDbSzN8Ttep1fdvXPQ9qlAJIagoi4/edit?usp=drivesdk
Theologians on Dubiety, Invalidity, Liberty & Law (on the principle Lex dubia non obligat, doubtful popes, and doubtful sacraments): https://docs.google.com/document/d/1-oXfp9ltVcg4fPH7GLtOa9Y9z-noL2buNEzT5pfpVlU/edit?usp=drivesdk
On the Theological Notes & Censures: https://docs.google.com/document/d/1TXVxtb6eWwTHw2VnxavHWn73QotI4kiTCv2VxEcqdgQ/edit?usp=drivesdk
On Dogma and Science: https://docs.google.com/document/d/1NAVVmVAYOIVqIdUGU2-NKWmNUnMjogFrA0J6g1FrMzg/edit?usp=drivesdk
Public Worship of God Exclusive to Catholicism: https://docs.google.com/document/d/1oxPigMZ5ADCqHwzYtNDlQVbhpCrSt-qYjyzTxHQFSFI/edit?usp=drivesdk
Infallibility of General Discipline: https://docs.google.com/document/d/1ehavuC5_kAlNpwj0lyLphIS978uWbt9FlMX3lyQV52E/edit?usp=drivesdk
On Moral Theology: https://docs.google.com/document/d/18SOpOgdbuTYJH3NgkJu8Z20_v4P4HpmUcgUBjXCR7KI/edit?usp=drivesdk
On Anglican Holy Orders: https://docs.google.com/document/d/19GPV2jbT4V7BSnW-Lcj4ksbQXMPvBl2BdY-BGa7CkDQ/edit?usp=drivesdk
Theologians on Church/State & Religious Liberty: https://docs.google.com/document/d/1Et07PBSh3NPzME0aynjA6ISnYQpp05H4tgtwP9btnjs/edit?usp=drivesdk
Theologians on Catholic Education: https://docs.google.com/document/d/1Ahbnt1i8WwBc6ksMS2oPM3TFVi8ccO0-9Kc9x5TYDZg/edit?usp=drivesdk
Theologians on Mixed Marriages: https://docs.google.com/document/d/1f3PCJ0Cy1ZaEgBC6TEgxuQJ4mewSgmqF2yAnTlm9W8w/edit?usp=drivesk
On Slavery, Sexism, Racism, Immigration: https://docs.google.com/document/d/1kyqaofrI1j8FEbUNFA-_HXZw76ZCFMxL7b7ajqwSk10/edit?usp=drivesdk
Miscellaneous Papal Quotes: https://docs.google.com/document/d/18GO69m6YIvOO5MjT49OEUfMxOtD7v57c7KjkkkUMf5I/edit?usp=drivesdk
Pius XII on Capitalism & Communism: https://docs.google.com/document/d/1QtLGTld1QiwoY5MzB_-vcbTYKToiL7Wc_K8nCEC0fxU/edit?usp=drivesdk
Quotes for Sedevacantists: https://docs.google.com/document/d/1H-5iGri3KDF-5PlmJ9-MPjH9dv5LkQVlqOKY5rUtL-s/edit?usp=drivesdk
The Ecclesial Revolution (regarding the infiltration and influence of Modernists within the Church): https://docs.google.com/document/d/1PsoTH6Gq2hrkC64gPx2G8xO20iPcOWNohp9pvypqo8Q/edit?usp=drivesdk
Popes on Novelty: https://docs.google.com/document/d/1oGHsA1E8SKhiMpv8BmoeT73PbHy1_XdxcgPOiLzV1k4/edit?usp=drivesdk
Popes on Unity: https://docs.google.com/document/d/19ek3DVLRGf6V0vCOlC3l5Qfjy6oUuof56AgadX23fZ0/edit?usp=drivesdk
Popes on Vernacular Scripture: https://docs.google.com/document/d/1A19U2MScmJpkZpxplzziJt9ymSXpRIAQPOLcoiKq6P0/edit?usp=drivesdk
Popes on Freedom of Conscience & Religion: https://docs.google.com/document/d/1AujelCV9WZpCZQJQjkOrtU0vTOPCXRr6ILbF6JCTGIk/edit?usp=drivesdk
Popes on Freedom of Speech & Press: https://docs.google.com/document/d/14hVFnxtH7CFOWAYNJP4Vt4FmPLciFbl7Dn3W2wGTlAw/edit?usp=drivesdk
Popes on State Authority: https://docs.google.com/document/d/1hPLH1Dk3AUpyhocBKP4SoGbIU3RRrBmktOZKfzoycUE/edit?usp=drivesdk
Popes on Union of Church & State: https://docs.google.com/document/d/1XK_RRFpnjdUgrikqcgs95i2c4T-s84NjafLBEpvvpPc/edit?usp=drivesdk
Popes on Seminarians, Priests, & Bishops: https://docs.google.com/document/d/1-W1KoOTQDo9KuEg6itCqAO2CVBM3FBxRWICdztdw208/edit?usp=drivesdk
Popes on Church Membership: https://docs.google.com/document/d/1VjBotIAqT5zzyRXXLrHLcPQ8IZO_6xWvdf_ELEv05UE/edit?usp=drivesdk
Letters of Innocent III: https://docs.google.com/document/d/1PWO2sgQRIXkybubUETAS37Ictu36bvim4bB8y2bqquU/edit?usp=drivesdk
Letters of Pope Leo Magnus: https://docs.google.com/document/d/1HT1HocZ_6iAhtuyNQV7TQbH8A2C_VCH_1b_QoYMpdUY/edit?usp=drivesdk
Pre-Schism Popes on the Papacy: https://docs.google.com/document/d/1JWdgUXxOucYK97gL1SBNCfO_tDXw5AZKZkYkvkFSFbw/edit?usp=drivesdk
Popes on the Papacy: https://docs.google.com/document/d/1K3cZH7N1w40KCP7yVYKVXvMNjdMkb5cL8ttESY0RHpc/edit?usp=drivesdk
Popes on the Proximate Rule of Faith: https://docs.google.com/document/d/1JxE2MWsP3rZDrfoml99q3iXo_sOwOYYtXk4dt0s_AHw/edit?usp=drivesdk
Popes on Capital Punishment & Just War: https://docs.google.com/document/d/13S2LIj5hbe9yXsLY3g23gyqZt4toH4pEVhmVhBEGAvY/edit?usp=drivesdk
Popes on Indifferentism & Salvation: https://docs.google.com/document/d/1NVPHJ_jiy534Iwx3a4i55ivM00OOX_6f5AdIjCf3cOA/edit?usp=drivesdk
Popes on Propagation & Preservation of the Faith: https://docs.google.com/document/d/1s5Q_t83UHGknLEleTis3gLJvWO8zk8oxB7SSXVubdh4/edit?usp=drivesdk
Popes on Penance & Temporal Punishment: https://docs.google.com/document/d/1YlHXWAjrZaAOt7SlquwmLRTvGnoI3ifU9y2FXl71nPY/edit?usp=drivesdk
Popes on Matrimony/Marriage https://docs.google.com/document/d/1IV9Hm0uHNuJWkOIVMHj8gnGaWK2XZwoPuW-09nTbZIw/edit?usp=drivesdk
Magisterial teachings of Pope Pius IX: https://docs.google.com/document/d/1_HZ-nUTkc7VBn3JSo6Pvi8uh9NT3q0DP_Jsq2-r2GuA/edit?usp=drivesdk
Magisterial teachings of pre-Pius IX Popes: https://docs.google.com/document/d/1KidsWdQOg9Qo3fkxcFAuOasEAc7HERSEQZ5GCpR5v70/edit?usp=drivesdk
Magisterial teachings of Pope Leo XIII: https://docs.google.com/document/d/1NUFXe1ZQXf6aqFfu1TfRdb9fwm_tAS1LUGB8kc84GmA/edit?usp=drivesdk
Magisterial teachings of Pope Benedict XV: https://docs.google.com/document/d/1CkygXyQF_V0Up5st1kQDkG60_tfoqIGg_Klhr5HaWzY/edit?usp=drivesdk
Pius XII -Documents: https://docs.google.com/document/d/1h2H86Q3SBoGpV85KvGpe1c84GPTmZpOzjaFHtuwsR4M/edit?usp=drivesdk
Popes on Education: https://docs.google.com/document/d/1lv3sJdv-q1KH6I8ydH0JvF2dqBN7bdmGAcPXnrTAu7E/edit?usp=drivesdk
Obscure Papal Documents: https://docs.google.com/document/d/1XjHyVi9ZbqUiTngZXQn4tAwU55RWUBV3LOA7HWjmF3A/edit?usp=drivesdk
Papal Authority Over Natural Law, Philosophy, & Economics: https://docs.google.com/document/d/1P26MISdpzMaACf40TWTv1pQRYEpHo45SSSbqbLsPyqc/edit?usp=drivesdk
Free Catholic Theology, miscellaneous books & articles: https://drive.google.com/folderview?id=15N_fxWUy5Hd3DFP6X49QlRSuTGHqw3ba
British Papists: https://drive.google.com/folderview?id=1AKqvBTOJoarSuJAa7jufq1Nly2eQ-RE6
Papal Power: https://drive.google.com/folderview?id=16HQmqw19-9BF69SfZCsXPANMdrXuEsUg
Cardinal Manning stuff: https://drive.google.com/folderview?id=1jnMBNPatsurhHj-4G-X45iC9i1r5VmnK
Cardinal Wiseman stuff: https://drive.google.com/folderview?id=1JEMxAQYC7AcyhtPaTrlXZ1rAheTLD9ng
Bishop Ullathorne stuff: https://drive.google.com/folderview?id=1l4EW_FLKy9mmoX08QsV3yqhVBp4N_Yfl
Orestes Brownson stuff: https://drive.google.com/folderview?id=1X_iE5JTec09fTrTha–x-q7n40T9ybWn
Frederick Oakeley stuff: https://drive.google.com/folderview?id=1hAEbFcnhW4WRWA6Toi7w7phjQaxkW498
Frederick William Faber stuff: https://drive.google.com/folderview?id=1GDuNuIr3NLl1jtiamd6r65yFmvvo1snW
Luke Rivington stuff: https://drive.google.com/folderview?id=1_nuvAc4X1JDxi__lKc9FZmNggnx1U2MH
Thomas More stuff: https://drive.google.com/folderview?id=115Wj50GAIl83dR5UpwdRqSzvTQctlTYK
Thomas Norton Harper stuff: https://drive.google.com/folderview?id=1TUySi_ajAhwTeRzphxVYnRp02BdGSJY0
Thomas William Allies stuff: https://drive.google.com/folderview?id=1aHsuFo2pfNLdu1F_bTL4yxPVQNUPrbKD
William George Ward stuff: https://drive.google.com/folderview?id=1AewCf1FE3BXJm5Z4lv9GxaXkG4fZb0Hk
Thomas Slater stuff: https://drive.google.com/folderview?id=1kPsCYcO3dzHSmDaR2XP31Gjv9_bupbLe
Henry Augustus Rawes stuff: https://drive.google.com/folderview?id=1Vpjoft2QAl7Fhdq242Te47_SSiHOxP2U
Medieval & Modern Theologians & Papal Writings in Latin (I cannot take credit for compiling these links, that honor goes to Timothy Gerard Aloysius Wilson):
https://docs.google.com/document/d/1JsfvRs5aVEdOGvIA3Tkn9YVHOftI4Q6kk655DxXC7ws/edit?usp=drivesdk
Note on the sources utilized: almost everything I quote is available freely online in the public domain, and accordingly, if anyone is interested in exactly where a quote comes from or whose translation it is, all that needs to be done is a simple search of the web for a short passage from the quoted work, and results with the desired information will be shown. I would list them myself, but the sheer volume of the quotes, and the basic method of attribution I have chosen to follow makes it rather tedious and cumbersome to do so. However, some general tips:
• everything from Pope St. Leo the Great, and most of the quotes from other Church Fathers, are from Philip Schaff’s “Ante-Nicene Fathers: The Writings of the Fathers Down to A.D. 325”, and can be found in the following places:
https://ccel.org/fathers
http://www.tertullian.org/fathers2/
The last website also hosts additional public domain translations of other patristic works:
http://tertullian.org/fathers/
https://www.newadvent.org/fathers/
The Schaff volumes are also on Google Books.
• everything by the modern popes (i.e., 1700s onwards) is from here:
https://www.papalencyclicals.net/
Most of the preceding documents, and many more in the modern era, are given on the Vatican’s website, under URLs like the following:
http://w2.vatican.va/content/pius-xii/en.html
http://w2.vatican.va/content/pius-xi/en.html
http://w2.vatican.va/content/benedict-xv/en.html
http://w2.vatican.va/content/pius-x/en.html
http://w2.vatican.va/content/leo-xiii/en.html
http://w2.vatican.va/content/pius-ix/en.html
http://www.vatican.va/archive/ass/index_en.htm
http://www.vatican.va/archive/aas/index_en.htm
Occasionally, a papal quote is from here:
http://denzinger.patristica.net/denzinger/
Nearly all quotes from Pope St. Gelasius are from the following excellent book, which, if you have sufficient finances for, I recommend buying either a physical or digital copy of (I bought the former):
http://www.brepols.net/Pages/ShowProduct.aspx?prod_id=IS-9782503552996-1
https://www.brepolsonline.net/action/showBook?doi=10.1484%2FM.ADNOT-EB.5.112451&#/doi/book/10.1484/M.ADNOT-EB.5.112451
Most quotes by Pope Innocent III are from this marvelous book (which, like the last, I recommend purchasing):
https://www.bookdepository.com/Between-God-Man-Pope-Innocent-III/9780813213651
Note on the value of repeated papal teachings.
Dr. William George Ward, Essays on the Church’s Doctrinal Authority, Extent of the Church’s Infallibility in Defining, Sixteenth Thesis: « When all the Pontiffs, who on any occasion treat of the same subject, are with one accord and with one mind mutually harmonious and accordant in perseveringly and absolutely inculcating some given selfsame proposition as a part of Catholic Doctrine—even if they do not teach such proposition explicitly ex cathedra—their agreement is to be held a sure sign, that [this proposition expresses] a Doctrine permanent in the mind of the Holy See, and therefore infallibly true. This is said almost in so many words by Father Martin, S.J., in his excellent work “De Matrimonio et potestate ipsum dirimendi” (vol ii., page 521). This Thesis is, I think, very useful for solving certain difficulties, which may otherwise result from what has been said above. For although indeed those Apostolical Acts may be not few, concerning winch it is impossible to be certain whether or not they are ex cathedra; nevertheless there is hardly anywhere (if indeed anywhere) a Pontifical Act to be found, inculcating as certain any Doctrine of moment, which Doctrine cannot be otherwise known as the uniform teaching of the Holy See and therefore infallible. But of what description are the utterances, of which we speak in this Thesis? F. Martin explains this admirably. They are “attestations which from time to time the Sovereign Pontiffs have put forward,—not indeed as teaching solemnly and ex cathedra, nor as defining Doctrine and imposing its belief on the faithful,—but nevertheless as Sovereign Pontiffs, exercising their most high charge of instructing and strengthening in the Faith whether the faithful or their Pastors; defending and protecting true Doctrine; and correcting errors. Thus in these testimonies is expressed the mind, judgment, and Doctrine of the Sovereign Pontiffs, not as of private doctors, but as of Sovereign Pontiffs. That is to say they are the utterances of Sovereign Pontiffs, engaged in teaching these or those Catholics some given truth, as fixed and determined, either by former Definition or by the Doctrine continuously handed down [in the Holy See]” (page 482). Or to put it in other words, they are utterances of the Pope, speaking Pontifically, but not ex cathedra; utterances which the Popes put forth, not as Universal Doctors, but as the Church’s “Gubernatores Doctrinales.” Now what proof can be offered of this Thesis? Let us again turn to Father Martin. “Although,” he says, “sometimes in some one Declaration of one Sovereign Pontiff one can see only his opinion as a private doctor, nevertheless, when many Popes” agree together, “it is certain that they do not merely express their private opinion. For otherwise there would issue that diversity of speech and thought, which is always found in private doctors who put forth their opinion on doubtful matters; because a private doctor does not instantly, on being made Pope, clothe himself as it were in the mere opinions of his Predecessor. But the mutual agreement of these several Pontiffs is to be held as a special sign of a Doctrine, either already defined, or at least fixed, consistent, abiding and established in [the mind of] the Holy See; for this unanimous and consistent agreement cannot in fact have any other cause” (page 521). But now any Doctrine, “abiding and established in the mind of the Holy See,” is without doubt infallibly true. “Ad hanc enim Ecclesiam propter potentiorem principalitatem necesse est omnem convenire Ecclesiam; hoc est, eos qui sunt undique fideles: in quâ semper ab his qui sunt undique conservata est ea quse ab Apostolis est Traditio.” And in this Nineteenth Century Pius IX. has taught this not less lucidly, than in the Third Century did S. Irenaeus. “This Seat of Blessed Peter in Rome has always kept whole and inviolate the Faith handed down by Christ, and has taught it to the faithful; showing to all the path of salvation and the Doctrine of uncorrupted truth” (“Qui pluribus,” November 9th, 1846). “In which [Roman Church] exists the infallible [irreformabile] magisterium of the same Faith: the magisterium founded by our Divine Redeemer” (“Noscitis et nobiscum,” December 8th, 1848). The Roman Church is “the centre of Catholic Truth and Unity, in which Church alone religion has been guarded inviolably, and from which all the other churches must derive their Tradition of Faith” (“Ineffabilis,” December 8th, 1854). Moreover the things are not few or of small moment, concerning which some definite Doctrine has always been delivered by a sufficiently long series of Popes. Concerning various philosophical questions; concerning the Temporal Power of the Church; concerning the mutual relations of Church and State; concerning the Pope’s Civil Princedom; concerning liberty of conscience and of the press; concerning mixed education; Popes, entirely differing in temperament and circumstances, have never spoken differently. And this unanimity, as F. Martin argues, can be referred to no other cause, than a consistent Tradition abiding in [the mind of] the Holy See. »
George May, “Encyclicals”, in Dictionary of Popes and the Papacy, edited by Bruno Steimer and Michael G. Parker, 2001: « Encyclicals contain no norms of canonical legislation. They are usually conditioned by specific timely questions or particular situations, and serve as a means for exercising the ordinary general magisterium of the pope, and ever since Leo XIII have been a primary source of the church’s preaching. As a rule they contain many doctrines that already have been put forth as dogmas. »
Pope Leo XIII, Inscrutabili Dei Consilio, 1878: « In the next place, in order that the union of hearts between their chief Pastor and the whole Catholic flock may daily be strengthened, We here call upon you, venerable brothers, with particular earnestness, and strongly urge you to kindle, with priestly zeal and pastoral care, the fire of the love of religion among the faithful entrusted to you, that their attachment to this chair of truth and justice may become closer and firmer, that they may welcome all its teachings with thorough assent of mind and will, wholly rejecting such opinion, even when most widely received, as they know to be contrary to the Church’s doctrine. In this matter, the Roman Pontiffs, Our predecessors, and the last of all, Pius IX, of sacred memory, especially in the General Council of the Vatican, have not neglected, so often as there was need, to condemn wide-spreading errors and to smite them with the apostolic condemnation. This they did, keeping before their eyes the words of St. Paul: “Beware lest any man cheat you by philosophy and vain deceit, according to the tradition of men, according to the elements of the world and not according to Christ.” [Col. 2:8] All such censures, We, following in the steps of Our predecessors, do confirm and renew from this apostolic seat of truth, whilst We earnestly ask of the Father of lights [James 1:17] that all the faithful, brought to thorough agreement in the like feeling and the same belief, may think and speak even as Ourselves. »
Pope Pius XI, Ubi Arcano Dei Consilio, 1922: « As an after-effect of the upheaval caused by the Great War and of its political and social consequences, false ideas and unhealthy sentiments have, like a contagious disease, so taken possession of the popular mind that We have grave fears that even some among the best of our laity and of the clergy, seduced by the false appearance of truth which some of these doctrines possess, have not been altogether immune from error.
Many believe in or claim that they believe in and hold fast to Catholic doctrine on such questions as social authority, the right of owning private property, on the relations between capital and labor, on the rights of the laboring man, on the relations between Church and State, religion and country, on the relations between the different social classes, on international relations, on the rights of the Holy See and the prerogatives of the Roman Pontiff and the Episcopate, on the social rights of Jesus Christ, Who is the Creator, Redeemer, and Lord not only of individuals but of nations. And these same people by their conversations, by their writings, and by their whole way of living conduct themselves no differently than if the doctrines and precepts promulgated so many times by the Supreme Pontiffs, especially by Leo XIII, Pius X, and Benedict XV, have either lost their original force or completely become obsolete. There is a species of moral, legal, and social modernism which We condemn, no less decidedly than We condemn theological modernism. »
Pope Pius XII, Humani Generis, 1950: « [G]enerally what is expounded and inculcated in Encyclical Letters already for other reasons appertains to Catholic doctrine. »
The statements of Ward, Leo XIII, Pius XI, and Pius XII should make it sufficiently plain that when the popes consistently teach something in their fallible ordinary magisterium, that their concurrence is not accidental, but rather expressive of the truth, and that since the ordinary magisterium cannot be habitually mistaken—for it too is aided by the grace of the Holy Spirit—whatever is taught habitually by the popes is infallibly true.
Note on the consensus of theologians.
« [W]here differences exist, we must in practice be guided by what theologians generally hold, and not insist on the doctrine of any single writer, however eminent, whose view is confessedly peculiar. » ~ Reverend Arthur Wollaston Hutton, The Anglican Ministry, 1879.
« The censure. . . of rashness or temerity, which means opposition to sound common opinion (communis), and this either for paltry reasons or no reasons at all. » ~ Sollier, Joseph. “Theological Censures.” The Catholic Encyclopedia. Vol. 3. New York: Robert Appleton Company, 1908. http://www.newadvent.org/cathen/03532a.htm
Daniel’s Catholic Resources 