The Unfailing Reliability of the Ordinary Magisterium

[I]t is evident that the Roman Pontiff has not been granted infallibility . . . as if he could dispose of it or count on it in any circumstance, but only when he speaks ex cathedra, and only in a doctrinal field limited to the truths of faith and morals, and to those that are intimately related to them.

Along with this infallibility of the ex cathedra definitions, there exists the charism of assistance of the Holy Spirit, granted to Peter and his successors so that they do not commit errors in matters of faith and morals, and, on the contrary, enlighten the Christian people well. This charism is not limited to exceptional cases, but embraces in varying degrees the whole exercise of the Magisterium.

- Pope St. John Paul II, General Audience, Wednesday, March 24, 1993

The Catholic Church teaches that revelation from God comes to us through the instrumentality of what could be called metaphorically a “three-legged stool.”  All three legs are necessary for the revelation to get to us safely.  The three legs are Scripture (the Word of God written in divinely-inspired documents), Tradition (the Word of God passed down in other ways—through the preaching, teaching, and practice of the Church through the ages), and the Magisterium (the divinely-appointed teachers of the true faith, the bishops in communion with the Bishop of Rome, successors to the Apostles, appointed by Christ and enabled by the Holy Spirit to authoritatively and effectively recognize, gather, preserve, transmit, unpack, teach, interpret, and apply God's revelation to the Church and to the world).  God has endowed all three of these legs with the gift of unfailing reliability, so that we can be sure that, by relying on them, we receive the true faith unmixed by any error.  Thus, the faithful are to submit to the judgment of the Scriptures and of Tradition as interpreted and taught by the Magisterium as the final authority for faith and morals.  While the entire deposit of the faith was given to the Church by Christ at the very beginning of her life, she grows in her understanding of all the implications of this revelation over time as she is guided by the Holy Spirit in the course of all that occurs to her over the centuries, and she applies the revelation in each new generation in ways that are particularly appropriate to the specifics of time and place.  (The Church articulates this, for example, in the Vatican II document Dei Verbum, Chapter II.)

The Church teaches in many different ways.  In particular, she teaches sometimes in a “definitive” manner and sometimes in a “non-definitive” manner.  She teaches "definitively" when she issues a teaching intended to provide a kind of final definition of some truth--to provide a final, unchanging word on some subject.  Such teaching is irreformable.  It will never change, grow obsolete, or be corrected based on future information or changing circumstances (though it may, of course, be even better understood with the passage of time).  It is absolutely certain.  The Church teaches “non-definitively” when she proposes teaching as true but not necessarily as the final, definitive word on a subject.  The teaching is authoritative, but there is not necessarily any guarantee that it will not be augmented or even corrected with the passage of time.  This teaching leads the people of God as they travel through the world and all its constant changes, but it doesn't always answer all their questions, and it is often to various degrees and in various ways contingent upon the specific circumstances of various times and places.  Although the Church can teach definitively in the course of her ordinary teaching, she often does so by making more specific, extraordinary pronouncements or decrees--such as the famous ex cathedra declarations of popes or the decrees of an ecumenical council.  Such teaching is often referred to as the "extraordinary magisterium."  Much of the "ordinary magisterium," on the other hand, is taken up with less-than-fully-definitive teaching.

The definitive teaching of the Church is blessed with the gift of infallibility.  It cannot err because it is granted the guidance of the Holy Spirit.  But how reliable are the non-definitive, ordinary magisterial teachings of the Church?  Are they capable of error?  Can we trust them implicitly, or do we need to be on our guard because they might sometimes lead us into error?  Do we need to subject them to our own private judgment and only receive them if they pass that test?  The answer is that the non-definitive, ordinary teaching of the Church is blessed by God with the gift of complete reliability just as is the definitive, extraordinary teaching of the Church.  But sometimes the claim is made by dissenters from some of the teaching of the ordinary magisterium that the Church's non-definitive teaching, since it is not irreformable in the same way that the definitive teaching is, is therefore not utterly reliable, and that we need to subject it to our own private judgment and sometimes even reject it.  My goal in this piece is to show why this is wrong and to defend the authoritativeness and absolute reliability of the Church's ordinary teaching.

The Gift of Reliability

Let's begin by quoting from the Catechism of the Catholic Church, which constitutes an official guide to authentic Church teaching.  As Pope St. John Paul II said when he promulgated it back in 1992, it is a “sure norm for teaching the faith.”  Here is how the Catechism describes the authority and reliability of the Church's Magisterium:

888 Bishops, with priests as co-workers, have as their first task "to preach the Gospel of God to all men," in keeping with the Lord's command.415 They are "heralds of faith, who draw new disciples to Christ; they are authentic teachers" of the apostolic faith "endowed with the authority of Christ."416 

889 In order to preserve the Church in the purity of the faith handed on by the apostles, Christ who is the Truth willed to confer on her a share in his own infallibility. By a "supernatural sense of faith" the People of God, under the guidance of the Church's living Magisterium, "unfailingly adheres to this faith."417 

890 The mission of the Magisterium is linked to the definitive nature of the covenant established by God with his people in Christ. It is this Magisterium's task to preserve God's people from deviations and defections and to guarantee them the objective possibility of professing the true faith without error. Thus, the pastoral duty of the Magisterium is aimed at seeing to it that the People of God abides in the truth that liberates. To fulfill this service, Christ endowed the Church's shepherds with the charism of infallibility in matters of faith and morals. The exercise of this charism takes several forms: 

891 "The Roman Pontiff, head of the college of bishops, enjoys this infallibility in virtue of his office, when, as supreme pastor and teacher of all the faithful - who confirms his brethren in the faith he proclaims by a definitive act a doctrine pertaining to faith or morals. . . . The infallibility promised to the Church is also present in the body of bishops when, together with Peter's successor, they exercise the supreme Magisterium," above all in an Ecumenical Council.418 When the Church through its supreme Magisterium proposes a doctrine "for belief as being divinely revealed,"419 and as the teaching of Christ, the definitions "must be adhered to with the obedience of faith."420 This infallibility extends as far as the deposit of divine Revelation itself.421 

892 Divine assistance is also given to the successors of the apostles, teaching in communion with the successor of Peter, and, in a particular way, to the bishop of Rome, pastor of the whole Church, when, without arriving at an infallible definition and without pronouncing in a "definitive manner," they propose in the exercise of the ordinary Magisterium a teaching that leads to better understanding of Revelation in matters of faith and morals. To this ordinary teaching the faithful "are to adhere to it with religious assent"422 which, though distinct from the assent of faith, is nonetheless an extension of it.  (Catechism of the Catholic Church, #888-892, embedded links removed, found here at the Vatican website)

We can see from the Catechism, particularly #888-890, that Christ has given to the Magisterium of the Church what I call the “gift of reliability.”  One of the main purposes of the Magisterium is to teach the faith authentically and effectively.  The Church's teachers are “endowed with the authority of Christ.”  Their job is to “preserve the Church in the purity of the faith handed on by the apostles” and to “preserve God's people from deviations and defections and to guarantee them the objective possibility of professing the true faith without error.”  “By a 'supernatural sense of faith' the People of God, under the guidance of the Church's living Magisterium, 'unfailingly adheres to this faith.'”  The people of God can rely on the Magisterium to lead them aright.  Relying on the Magisterium can never lead them astray.

The concept of the absolute reliability of the Church's Magisterium is fundamental to the very logic of Catholic epistemology.  The very thing that differentiates the Catholic epistemological approach from that of Protestantism is that Catholics look to the Church as the final judge of how to correctly understand God's revelation and its application to life.  Protestants rely on Scripture alone as unfailingly reliable (at least theoretically).  This is illustrated well in Martin Luther's famous response when required by the Catholic Church to recant his teachings at the Diet of Worms in 1521:

Unless I am convinced by Scripture and plain reason - I do not accept the authority of the popes and councils, for they have contradicted each other - my conscience is captive to the Word of God. I cannot and I will not recant anything for to go against conscience is neither right nor safe. God help me. Amen. (Retrieved from http://www.luther.de/en/worms.html at 12:53 PM on 2/19/18)

The Catholic response is very different.  When faced with a conflict between his own interpretation of revelation and the Church's official interpretation, the Catholic trusts the Church implicitly as inherently reliable.  The Catholic Church has always followed this procedure from the days of the earliest Church Fathers.  (See here and here for some evidence for this.)

The Eastern Orthodox Church shares this attitude with the Catholic Church.  What differentiates Catholics from Orthodox is that Catholics believe that a special gift of reliability has been given to the Bishop of Rome, the Pope, the Successor of St. Peter, so that the absolute reliability attributable to the Church's Magisterium as a whole is also attributable specifically to him.  (See here and here for some evidence of this doctrine in the Church Fathers.)  By means of papal authority, the Church is even more securely preserved from error and from schism.  St. Jerome put it this way:

[T]he Church was founded upon Peter: although elsewhere the same is attributed to all the Apostles, and they all receive the keys of the kingdom of heaven, and the strength of the Church depends upon them all alike, yet one among the twelve is chosen so that when a head has been appointed, there may be no occasion for schism.  (Against Jovinianus [Book I], section 26. Translated by W.H. Fremantle, G. Lewis and W.G. Martley. From Nicene and Post-Nicene Fathers, Second Series, Vol. 6. Edited by Philip Schaff and Henry Wace. [Buffalo, NY: Christian Literature Publishing Co., 1893.] Revised and edited for New Advent by Kevin Knight. .)

I could cite a vast testimony of many quotations showing Church teaching regarding the absolute reliability of the magisterium of the bishops of the Church as a whole and their incapability of falling into or leading the people of God into any error (see here for abundant testimony from the Fathers), but for the interest of brevity I will focus on the Church's testimony regarding the absolute reliability of the See of St. Peter.  At the First Vatican Council, as the Church was coming to define more specifically the dogma of the infallibility of the Pope, a very helpful and illuminating collection of references from various periods of Church history were brought together and cited as evidence of the Church's constant teaching through the ages on the utter reliability and infallibility and also the supreme authority of the Chair of St. Peter.  Here is a sampling of some of that testimony:

Wherefore we teach and declare that, by divine ordinance, the Roman Church possesses a pre-eminence of ordinary power over every other Church, and that this jurisdictional power of the Roman Pontiff is both episcopal and immediate. Both clergy and faithful, of whatever rite and dignity, both singly and collectively, are bound to submit to this power by the duty of hierarchical subordination and true obedience, and this not only in matters concerning faith and morals, but also in those which regard the discipline and government of the Church throughout the world.  (Vatican I, Session 4, Chapter 3, Section 2, as found on the EWTN website.  "The translation found here is that which appears in Decrees of the Ecumenical Councils ed. Norman Tanner. S.J. The numbering of the canons is however found in Tanner's text.") 

Since the Roman Pontiff, by the divine right of the apostolic primacy, governs the whole Church, we likewise teach and declare that he is the supreme judge of the faithful [52], and that in all cases which fall under ecclesiastical jurisdiction recourse may be had to his judgment [53]. The sentence of the Apostolic See (than which there is no higher authority) is not subject to revision by anyone, nor may anyone lawfully pass judgment thereupon [54]. And so they stray from the genuine path of truth who maintain that it is lawful to appeal from the judgments of the Roman pontiffs to an ecumenical council as if this were an authority superior to the Roman Pontiff.  (Chapter 3, Section 8) 

2. So the fathers of the fourth Council of Constantinople, following the footsteps of their predecessors, published this solemn profession of faith: The first condition of salvation is to maintain the rule of the true faith. And since that saying of our lord Jesus Christ, You are Peter, and upon this rock I will build my Church [55], cannot fail of its effect, the words spoken are confirmed by their consequences. For in the Apostolic See the Catholic religion has always been preserved unblemished, and sacred doctrine been held in honor. Since it is our earnest desire to be in no way separated from this faith and doctrine, we hope that we may deserve to remain in that one communion which the Apostolic See preaches, for in it is the whole and true strength of the Christian religion [56]. 

What is more, with the approval of the second Council of Lyons, the Greeks made the following profession:
"The Holy Roman Church possesses the supreme and full primacy and principality over the whole Catholic Church. She truly and humbly acknowledges that she received this from the Lord himself in blessed Peter, the prince and chief of the apostles, whose successor the Roman Pontiff is, together with the fullness of power. And since before all others she has the duty of defending the truth of the faith, so if any questions arise concerning the faith, it is by her judgment that they must be settled." [57]  (Chapter 4, Section 2) 

4. It was for this reason that the bishops of the whole world, sometimes individually, sometimes gathered in synods, according to the long established custom of the Churches and the pattern of ancient usage referred to this Apostolic See those dangers especially which arose in matters concerning the faith. This was to ensure that any damage suffered by the faith should be repaired in that place above all where the faith can know no failing [59].  (Chapter 4, Section 4) 

Indeed, their apostolic teaching was embraced by all the venerable fathers and reverenced and followed by all the holy orthodox doctors, for they knew very well that this See of St. Peter always remains unblemished by any error, in accordance with the divine promise of our Lord and Savior to the prince of his disciples: I have prayed for you that your faith may not fail; and when you have turned again, strengthen your brethren [60].  (Chapter 4, Section 6) 

This gift of truth and never-failing faith was therefore divinely conferred on Peter and his successors in this See so that they might discharge their exalted office for the salvation of all, and so that the whole flock of Christ might be kept away by them from the poisonous food of error and be nourished with the sustenance of heavenly doctrine. Thus the tendency to schism is removed and the whole Church is preserved in unity, and, resting on its foundation, can stand firm against the gates of hell.  (Chapter 4, Section 7)

We see here stated in very clear terms the absolute and supreme authority and reliability of the papal magisterium, which holds in itself the same authority and infallibility the Magisterium of the Church in general holds.  The See of St. Peter is "always unblemished by any error."  It is the supreme authority in the Church, so that "if any questions arise concerning the faith, it is by her judgment that they must be settled."  "The sentence of the Apostolic See (than which there is no higher authority) is not subject to revision by anyone, nor may anyone lawfully pass judgment thereupon."  The faith can have no failing in the Apostolic See.  Therefore, it is eminently and absolutely safe to rely on its judgment.  One cannot be led into error by relying on papal teaching.  Quite the contrary, in the Pope's teaching is "the whole and true strength of the Christian religion."  Reliance on the papal magisterium, therefore, and in general on the authentic Magisterium of the Catholic Church, removes any possibility of error or schism, for by following that Magisterium the faithful are all united in the fullness of the truth.

Definitive Magisterial Teaching

I mentioned earlier that magisterial teaching comes in two forms--definitive and non-definitive.  We can now look at each of these forms of teaching with regard to their authority and reliability.  Let's begin with definitive teaching.

In a document published in 1998 as a commentary on a new profession of faith (the Professio fide) promulgated by Pope John Paul II, the Congregation for the Doctrine of the Faith, an official arm of the papal magisterium, described in some detail the various forms of teaching in the Catholic Church and the various forms of assent required of them.  The document describes the definitive magisterial teaching of the Church in this way:

5. The first paragraph states: "With firm faith, I also believe everything contained in the word of God, whether written or handed down in Tradition, which the Church, either by a solemn judgement or by the ordinary and universal Magisterium, sets forth to be believed as divinely revealed". The object taught in this paragraph is constituted by all those doctrines of divine and catholic faith which the Church proposes as divinely and formally revealed and, as such, as irreformable.11 

These doctrines are contained in the word of God, written or handed down, and defined with a solemn judgement as divinely revealed truths either by the Roman Pontiff when he speaks 'ex cathedra,' or by the College of Bishops gathered in council, or infallibly proposed for belief by the ordinary and universal Magisterium. 

These doctrines require the assent of theological faith by all members of the faithful. Thus, whoever obstinately places them in doubt or denies them falls under the censure of heresy, as indicated by the respective canons of the Codes of Canon Law.12 

6. The second proposition of the Professio fidei states: "I also firmly accept and hold each and everything definitively proposed by the Church regarding teaching on faith and morals". The object taught by this formula includes all those teachings belonging to the dogmatic or moral area,13 which are necessary for faithfully keeping and expounding the deposit of faith, even if they have not been proposed by the Magisterium of the Church as formally revealed.

Such doctrines can be defined solemnly by the Roman Pontiff when he speaks 'ex cathedra' or by the College of Bishops gathered in council, or they can be taught infallibly by the ordinary and universal Magisterium of the Church as a 'sententia definitive tenenda'.14 Every believer, therefore, is required to give firm and definitive assent to these truths, based on faith in the Holy Spirit's assistance to the Church's Magisterium, and on the Catholic doctrine of the infallibility of the Magisterium in these matters.15 Whoever denies these truths would be in a position of rejecting a truth of Catholic doctrine16 and would therefore no longer be in full communion with the Catholic Church. 

7. The truths belonging to this second paragraph can be of various natures, thus giving different qualities to their relationship with revelation. There are truths which are necessarily connected with revelation by virtue of an historical relationship, while other truths evince a logical connection that expresses a stage in the maturation of understanding of revelation which the Church is called to undertake. The fact that these doctrines may not be proposed as formally revealed, insofar as they add to the data of faith elements that are not revealed or which are not yet expressly recognized as such, in no way diminishes their definitive character, which is required at least by their intrinsic connection with revealed truth. Moreover, it cannot be excluded that at a certain point in dogmatic development, the understanding of the realities and the words of the deposit of faith can progress in the life of the Church, and the Magisterium may proclaim some of these doctrines as also dogmas of divine and catholic faith.  (Congregation for the Doctrine of the Faith, Doctrinal Commentary on the Concluding Formula of the Professio fidei, #5-7, found here on the Vatican website)

There are two kinds of definitive teaching.  There are teachings that are directly divinely revealed.  Then there are teachings that are necessarily connected with teachings that are divinely revealed.  Also, there are different forms in which definitive teaching might be expressed.  The Pope or the bishops might make a formal pronouncement defining some doctrine.  Or the Pope or the bishops might simply teach a doctrine definitively without making a formal pronouncement.  The key element that unites all these teachings and forms of teaching together is that they are definitive.  They are intended as the irreformable final word on a subject.  The faithful are required to accept and submit to them as such.

Non-Definitive Ordinary Magisterial Teaching

Catholic language regarding the extraordinary and the ordinary magisterium is somewhat flexible.  While the language of extraordinary magisterium always refers to definitive magisterial pronouncements, the language of ordinary magisterium sometimes straddles the fence between definitive and non-definitive teaching.  This is because, as we saw above, definitive teaching can be given both in the form of solemn pronouncements but also in the course of the more ordinary regular teaching of the popes and bishops.  But under the category of ordinary magisterium also falls the regular, ongoing, not-necessarily-definitive teaching of the Church.  As we will see, the level of definitiveness in any given teaching in the ordinary magisterium is determined by the manifest intention of the teacher.

Here is the Congregation for the Doctrine of the Faith on the non-definitive teaching of the Church:

10. The third proposition of the Professio fidei states: "Moreover, I adhere with religious submission of will and intellect to the teachings which either the Roman Pontiff or the College of Bishops enunciate when they exercise their authentic Magisterium, even if they do not intend to proclaim these teachings by a definitive act". 

To this paragraph belong all those teachings – on faith and morals – presented as true or at least as sure, even if they have not been defined with a solemn judgement or proposed as definitive by the ordinary and universal Magisterium. Such teachings are, however, an authentic expression of the ordinary Magisterium of the Roman Pontiff or of the College of Bishops and therefore require religious submission of will and intellect.18 They are set forth in order to arrive at a deeper understanding of revelation, or to recall the conformity of a teaching with the truths of faith, or lastly to warn against ideas incompatible with those truths or against dangerous opinions that can lead to error.19 

A proposition contrary to these doctrines can be qualified as erroneous or, in the case of teachings of the prudential order, as rash or dangerous and therefore 'tuto doceri non potest' ['not possible to be taught safely'].20 . . . 

As examples of doctrines belonging to the third paragraph, one can point in general to teachings set forth by the authentic ordinary Magisterium in a non-definitive way, which require degrees of adherence differentiated according to the mind and the will manifested; this is shown especially by the nature of the documents, by the frequent repetition of the same doctrine, or by the tenor of the verbal expression.38  (Doctrinal Commentary, #10, 11)

The non-definitive teaching of the Church, although it is not intended necessarily to be final or irreformable, is authoritative.  It is not "up for grabs," but is binding on the mind and will of the faithful, who are required to accept it and assent to it.  This is because, as with all magisterial teaching, non-definitive ordinary teaching comes with the authority of Christ and with the divine assistance of the Holy Spirit.  We saw this articulated in our quotation from the Catechism earlier in this article:

892 Divine assistance is also given to the successors of the apostles, teaching in communion with the successor of Peter, and, in a particular way, to the bishop of Rome, pastor of the whole Church, when, without arriving at an infallible definition and without pronouncing in a "definitive manner," they propose in the exercise of the ordinary Magisterium a teaching that leads to better understanding of Revelation in matters of faith and morals. To this ordinary teaching the faithful "are to adhere to it with religious assent"422 which, though distinct from the assent of faith, is nonetheless an extension of it.

The Code of Canon Law makes the same points:

Can. 752 Although not an assent of faith, a religious submission of the intellect and will must be given to a doctrine which the Supreme Pontiff or the college of bishops declares concerning faith or morals when they exercise the authentic magisterium, even if they do not intend to proclaim it by definitive act; therefore, the Christian faithful are to take care to avoid those things which do not agree with it.  (Catholic Church, Code of Canon Law, Canon 752, embedded links removed, found here on the Vatican website)

Another document from the Congregation for the Doctrine of the Faith, Donum Veritatis ("On the Ecclesial Vocation of the Theologian"), provides another articulation of the same teaching:

17. Divine assistance is also given to the successors of the apostles teaching in communion with the successor of Peter, and in a particular way, to the Roman Pontiff as Pastor of the whole Church, when exercising their ordinary Magisterium, even should this not issue in an infallible definition or in a "definitive" pronouncement but in the proposal of some teaching which leads to a better understanding of Revelation in matters of faith and morals and to moral directives derived from such teaching. 

One must therefore take into account the proper character of every exercise of the Magisterium, considering the extent to which its authority is engaged. It is also to be borne in mind that all acts of the Magisterium derive from the same source, that is, from Christ who desires that His People walk in the entire truth. For this same reason, magisterial decisions in matters of discipline, even if they are not guaranteed by the charism of infallibility, are not without divine assistance and call for the adherence of the faithful. . . . 

When the Magisterium, not intending to act "definitively", teaches a doctrine to aid a better understanding of Revelation and make explicit its contents, or to recall how some teaching is in conformity with the truths of faith, or finally to guard against ideas that are incompatible with these truths, the response called for is that of the religious submission of will and intellect.(23) This kind of response cannot be simply exterior or disciplinary but must be understood within the logic of faith and under the impulse of obedience to the faith.  (Congregation for the Doctrine of the Faith, Donum Veritatis, #17, 23, found here on the Vatican website)

The Vatican II document Lumen Gentium puts it this way:

25. Among the principal duties of bishops the preaching of the Gospel occupies an eminent place.(39*) For bishops are preachers of the faith, who lead new disciples to Christ, and they are authentic teachers, that is, teachers endowed with the authority of Christ, who preach to the people committed to them the faith they must believe and put into practice, and by the light of the Holy Spirit illustrate that faith. They bring forth from the treasury of Revelation new things and old,(164) making it bear fruit and vigilantly warding off any errors that threaten their flock.(165) Bishops, teaching in communion with the Roman Pontiff, are to be respected by all as witnesses to divine and Catholic truth. In matters of faith and morals, the bishops speak in the name of Christ and the faithful are to accept their teaching and adhere to it with a religious assent. This religious submission of mind and will must be shown in a special way to the authentic magisterium of the Roman Pontiff, even when he is not speaking ex cathedra; that is, it must be shown in such a way that his supreme magisterium is acknowledged with reverence, the judgments made by him are sincerely adhered to, according to his manifest mind and will. His mind and will in the matter may be known either from the character of the documents, from his frequent repetition of the same doctrine, or from his manner of speaking.  (Vatican II, Lumen Gentium, #25, found here at the Vatican website)

Pope Pius XII, in his Encyclical Humani Generis, adds yet another forceful exhortation concerning the assent owed to the ordinary magisterium:

20. Nor must it be thought that what is expounded in Encyclical Letters does not of itself demand consent, since in writing such Letters the Popes do not exercise the supreme power of their Teaching Authority. For these matters are taught with the ordinary teaching authority, of which it is true to say: "He who heareth you, heareth me";[3] and generally what is expounded and inculcated in Encyclical Letters already for other reasons appertains to Catholic doctrine. But if the Supreme Pontiffs in their official documents purposely pass judgment on a matter up to that time under dispute, it is obvious that that matter, according to the mind and will of the Pontiffs, cannot be any longer considered a question open to discussion among theologians.  (Pope Pius XII, Humani Generis, #20, found here at the Vatican website)

It at this point that we find some Catholics attempting to find a loophole in order to dissent from certain non-definitive magisterial teachings.  Some Catholics interpret the assent required to non-definitive teaching not so much as assent but as something like "respectful or deferential consideration," as if the faithful are allowed to dissent from such teaching if, having passed it through the sifting of their own private judgment, they find it to be defective in some manner.  But the Church does not allow this kind of dissent.

33. Dissent has different aspects. In its most radical form, it aims at changing the Church following a model of protest which takes its inspiration from political society. More frequently, it is asserted that the theologian is not bound to adhere to any Magisterial teaching unless it is infallible. Thus a Kind of theological positivism is adopted, according to which, doctrines proposed without exercise of the charism of infallibility are said to have no obligatory character about them, leaving the individual completely at liberty to adhere to them or not. The theologian would accordingly be totally free to raise doubts or reject the non-infallible teaching of the Magisterium particularly in the case of specific moral norms. With such critical opposition, he would even be making a contribution to the development of doctrine.  (Donum Veritatis, #33)

There is a kernel of truth in this dissenting attitude, however.  It is true that there are various levels of authoritativeness in Church teaching.  Not everything the Pope or the bishops say is intended by them to be binding.  Sometimes aspects of what is said are intended as binding but other aspects are not.  There is certainly room for respectful criticism of the Pope and the bishops with regard to moral behavior, diligence in carrying out their callings, and even at times aspects of their teaching.  Donum Veritatis addresses this:

24. Finally, in order to serve the People of God as well as possible, in particular, by warning them of dangerous opinions which could lead to error, the Magisterium can intervene in questions under discussion which involve, in addition to solid principles, certain contingent and conjectural elements. It often only becomes possible with the passage of time to distinguish between what is necessary and what is contingent. 

The willingness to submit loyally to the teaching of the Magisterium on matters per se not irreformable must be the rule. It can happen, however, that a theologian may, according to the case, raise questions regarding the timeliness, the form, or even the contents of magisterial interventions. Here the theologian will need, first of all, to assess accurately the authoritativeness of the interventions which becomes clear from the nature of the documents, the insistence with which a teaching is repeated, and the very way in which it is expressed.(24) 

When it comes to the question of interventions in the prudential order, it could happen that some Magisterial documents might not be free from all deficiencies. Bishops and their advisors have not always taken into immediate consideration every aspect or the entire complexity of a question. But it would be contrary to the truth, if, proceeding from some particular cases, one were to conclude that the Church's Magisterium can be habitually mistaken in its prudential judgments, or that it does not enjoy divine assistance in the integral exercise of its mission. In fact, the theologian, who cannot pursue his discipline well without a certain competence in history, is aware of the filtering which occurs with the passage of time. This is not to be understood in the sense of a relativization of the tenets of the faith. The theologian knows that some judgments of the Magisterium could be justified at the time in which they were made, because while the pronouncements contained true assertions and others which were not sure, both types were inextricably connected. Only time has permitted discernment and, after deeper study, the attainment of true doctrinal progress. (Donum Veritatis, #24)

Such a disagreement could not be justified if it were based solely upon the fact that the validity of the given teaching is not evident or upon the opinion that the opposite position would be the more probable. Nor, furthermore, would the judgment of the subjective conscience of the theologian justify it because conscience does not constitute an autonomous and exclusive authority for deciding the truth of a doctrine. (#28)

It is crucial to notice here two things:  1. The rule is submission.  This means that, if we want to criticize or disagree with some magisterial teaching, the burden of proof is on us to show that there is a just basis for such disagreement.  2. Criticism of or disagreement with expressions of the Magisterium can only go so far as the Magisterium itself allows.  "Here the theologian will need, first of all, to assess accurately the authoritativeness of the interventions which becomes clear from the nature of the documents, the insistence with which a teaching is repeated, and the very way in which it is expressed."  Donum Veritatis here reiterates what we've seen in other places:  Non-definitive magisterial teachings "require degrees of adherence differentiated according to the mind and the will manifested; this is shown especially by the nature of the documents, by the frequent repetition of the same doctrine, or by the tenor of the verbal expression" (Doctrinal Commentary #11).  We can indeed, at times, criticize and even disagree with some of the things the bishops and the Pope say.  But the real question is, Who determines the degree and form of assent required in any particular case?  The erroneous dissenters make themselves and their own judgment the determining factor in deciding what they are required to assent to and to what degree they are required to assent.  But the Church teaches that it is the bishops and the Pope who make that determination.  We don't get to subject the teachings of the bishops and the Pope to our own judgment and decide, even against their intentions and requirements, what we will agree with and what we will disagree with.  We must assent to their teaching according to their manifest mind and will.  We must accept even non-definitive magisterial teaching as inherently reliable, so that we will not subject it to our judgment and disagree with it if the "validity of the given teaching is not evident or upon the opinion that the opposite position would be the more probable."  So while there can sometimes legitimately be disagreement with some things the Pope or bishops say, there can never be dissent from magisterial teaching, in the sense of refusal to accept magisterial teaching to the extent that it is intended as authoritative and binding.  Whenever and to the extent that the bishops and/or the Pope make use of their magisterial authority with the intention to give to the Church an authentic, official teaching, leading the people of God into truth or showing them how to stay faithful to the truth, that teaching must be assented to.

Donum Veritatis goes on (in sections 24-31) to discuss what should be done if a theologian were to find himself intellectually unable to submit to some non-definitive teaching of the Church.  I won't quote the whole section, but the gist of it is that the theologian is required to submit to the Church's judgment as best he can.  If he has an intellectual problem with the Church's teaching, he is to dialogue with the Church, trying as hard as he can to understand the Church's point of view and to allow the Church to show him where he may be going wrong.  He is not to go out and promote his concerns in the mass media, putting himself in opposition to the Church.  He is not to present his "opinions or divergent hypotheses as though they were non-arguable conclusions" (#27).  He can criticize and disagree with the prudential judgments of the Church that don't involve matters of the doctrine of the faith to the extent that the Church allows him to do so, but he is not to think that the Church's non-definitive teaching is "up for grabs."

It is acknowledged that there might be some situations where a theologian, trying as best he can, simply cannot bring himself intellectually to accept certain non-definitive teachings.  In such a case, the Church wants to show mercy to him and sympathizes with him, knowing that "such a situation can certainly prove a difficult trial. It can be a call to suffer for the truth, in silence and prayer, but with the certainty, that if the truth really is at stake, it will ultimately prevail" (#31).  In the meantime, he must remain humbly in dialogue with the Church, open to being corrected, and not make himself a public opponent of the Church's teaching or form some kind of movement of "dissent."

So does Donum Veritatis say that the Church gives permission to theologians to disagree with non-definitive teachings of the Church?  Hardly.  It is rather saying that they have a duty to submit intellectually and practically to the Church's non-definitive teaching as far as they are able to do so, but that the Church wants to be sympathetic and merciful to them if they find themselves stuck with regard to some point, provided they remain humble and open to correction and don't join or form a movement of "dissent."  But the teaching of the Church is still not "up for grabs."  We are not allowed to treat it as if it is merely the expression of an opinion which is not binding on us, as if we have the right to consider it and reject it if we find some other position more probable.

Note also that the Code of Canon Law of the Church says that those who defy even non-definitive magisterial teaching, or who promote dissent and rebellion against the Church, can be subject to penalty.  We quoted Canon #752 earlier:

Although not an assent of faith, a religious submission of the intellect and will must be given to a doctrine which the Supreme Pontiff or the college of bishops declares concerning faith or morals when they exercise the authentic magisterium, even if they do not intend to proclaim it by definitive act; therefore, the Christian faithful are to take care to avoid those things which do not agree with it.

Now we see the follow up in terms of the penalty that disobedience to this might bring:

Can. 1364 §1. Without prejudice to the prescript of can. 194, §1, n. 2, an apostate from the faith, a heretic, or a schismatic incurs a latae sententiae excommunication; in addition, a cleric can be punished with the penalties mentioned in can. 1336, §1, nn. 1, 2, and 3.

§2. If contumacy of long duration or the gravity of scandal demands it, other penalties can be added, including dismissal from the clerical state.

Can. 1371 The following are to be punished with a just penalty:

1/ in addition to the case mentioned in can. 1364, §1, a person who teaches a doctrine condemned by the Roman Pontiff or an ecumenical council or who obstinately rejects the doctrine mentioned in can. 750, §2 or in can. 752 and who does not retract after having been admonished by the Apostolic See or an ordinary;

2/ a person who otherwise does not obey a legitimate precept or prohibition of the Apostolic See, an ordinary, or a superior and who persists in disobedience after a warning.

Can. 1372 A person who makes recourse against an act of the Roman Pontiff to an ecumenical council or the college of bishops is to be punished with a censure.

Can. 1373 A person who publicly incites among subjects animosities or hatred against the Apostolic See or an ordinary because of some act of power or ecclesiastical ministry or provokes subjects to disobey them is to be punished by an interdict or other just penalties.

Can. 1374 A person who joins an association which plots against the Church is to be punished with a just penalty; however, a person who promotes or directs an association of this kind is to be punished with an interdict.  (Catholic Church, Code of Canon Law, Canon 1364, 1371-1374, embedded links and arrow-links removed, found here and here on the Vatican website.)

The fact that Canon Law specifically spells out that disobedience and dissent to even non-definitive magisterial teaching deserves a penalty simply reinforces what we've already seen--that assent to non-definitive teaching, and therefore acceptance of it as reliable, is taught and required by the Church.

Is Non-Definitive Magisterial Teaching Infallible?

We have seen that the non-definitive teaching of the Magisterium, like its definitive teaching, is authoritative and inherently reliable.  So how do definitive teaching and non-definitive teaching differ?  Does the unfailing reliability of non-definitive teaching imply that such teaching is infallible?  Let's shed some light on this question by looking at some quotations from Pope St. John Paul II from a couple of papal general audiences from March 17 and 24, 1993 (these were part of a series of audiences dealing with the nature of papal authority and infallibility, the addressses most pertinent to our topic being those of March 10, March 17, and March 24).

2. This supreme authority of the papal magisterium, which traditionally is usually defined apostolic, also in its ordinary exercise, derives from the institutional fact by which the Roman Pontiff is the successor of Peter in the mission to teach, confirm his brothers and ensure the conformity of the preaching of the Church with the deposit of the faith of the Apostles and with the doctrine of Christ. But it also derives from the conviction, matured in the Christian tradition, that the Bishop of Rome is the heir of Peter also in the charisms of special assistance that Jesus assured him when he said: «I have prayed for you» (Lc.22, 32). This means a continuous help of the Holy Spirit in the whole exercise of the doctrinal mission, aimed at making understood the revealed truth and its consequences in human life. 

For this reason, the Second Vatican Council affirms that the whole teaching of the Pope deserves to be heard and accepted, even when it is not ex cathedra, but presented in the ordinary exercise of the magisterium with clear intention to enunciate, remember or reaffirm the doctrine of faith. It is a consequence of the institutional fact and of the spiritual inheritance given by the complete dimensions of Peter's succession.  (Pope John Paul II, General Audience, Wednesday, March 17, 1993, #2, found here on the Vatican website, translated from Spanish, with slight tweaking, by the automatic translation system on Google Chrome) 

However, it is evident that the Roman Pontiff has not been granted infallibility as a private person, but rather that he is the pastor and teacher of all Christians. Moreover, he does not exercise it as having authority in himself or in himself, but "by his supreme apostolic authority" and "by the assistance of the Holy Spirit, promised to him in the person of St. Peter." Finally, he does not possess it as if he could dispose of it or count on it in any circumstance, but only when he speaks ex cathedra, and only in a doctrinal field limited to the truths of faith and morals, and to those that are intimately related to them. . . . 

3. The conciliar texts also specify the conditions for the exercise of the infallible magisterium by the Roman Pontiff. They can be summarized as follows: the Pope must act as pastor and teacher of all Christians, pronouncing on truths of faith and customs, with terms that clearly state their intention to define a certain truth and demand definitive adherence to it by all the Christians. This is what happened, for example, in the definition of the Immaculate Conception of Mary, about which Pius IX said: "It is a doctrine revealed by God and must therefore be firmly and constantly believed by all the faithful" (DS 2803); or also in the definition of the Assumption of Mary Most Holy, when Pius XII said: "By the authority of our Lord Jesus Christ, of the blessed apostles Peter and Paul, and ours, we proclaim, declare and define to be divinely revealed dogma ..." ( DS 3903). 

With these conditions one can speak of extraordinary papal magisterium, whose definitions are irreformable "by themselves and not by the consent of the Church" (ex sese, non autem ex consensu Ecclesiae). That means that these definitions, in order to be valid, do not need the consent of the bishops: neither of a previous consent, nor of a consistent consent, "because they were proclaimed under the assistance of the Holy Spirit, promised to him (to the Roman Pontiff) in the person of St. Peter, and not needing any approval from others nor admitting an appeal to another court " (Lumen gentium, 25). 

4. The Supreme Pontiffs can exercise this form of teaching. And in fact, this has happened. But many Popes have not exercised it. Now, it is necessary to observe that in the conciliar texts that we are explaining, a distinction is made between the ordinary and the extraordinary magisterium, emphasizing the importance of the former, which is permanent and continuous, while the one expressed in the definitions can be called exceptional. 

Along with this infallibility of the ex cathedra definitions, there exists the charism of assistance of the Holy Spirit, granted to Peter and his successors so that they do not commit errors in matters of faith and morals, and, on the contrary, enlighten the Christian people well. This charism is not limited to exceptional cases, but embraces in varying degrees the whole exercise of the Magisterium.  (Pope John Paul II, General Audience, Wednesday, March 24, 1993, #1, 3-4, found here on the Vatican website, translated from Spanish, with slight tweaking inspired by the translation at http://totus2us.com/vocation/jpii-catechesis-on-the-church/the-holy-spirit-assists-the-roman-pontiff/, by the automatic translation system on Google Chrome)

Is the non-definitive teaching of the ordinary magisterium infallible?  The answer is: yes and no.  As we can see in the quotations from Pope John Paul II above and throughout this article, the non-definitive teaching of the Church is often, in the language of the Church, referred to as not being infallible or as contrasted with or distinguished from the "infallible," definitive teaching of the Church.  This is because non-definitive teaching, unlike definitive teaching, is not irreformable.  It is not intended necessarily to provide the final word on any specific subject or to make a pronouncement that is to be unchangeable for all time.  It is sometimes subject to further enhancement or even correction from changing circumstances, new information, or growth in awareness.  And yet, as Pope John Paul II says, all the teaching of the Pope in his ordinary magisterium has the "charism of assistance of the Holy Spirit, granted to Peter and his successors so that they do not commit errors in matters of faith and morals, and, on the contrary, enlighten the Christian people well."  Although this more general charism is distinguished from the more specific charism of infallibility, it nevertheless partakes of a kind of infallibility.

How can this be?  The difference between definitive and non-definitive teaching is not in the reliability of these teachings, but in the scope of the intention.  Non-definitive teachings are not intended to reach as far as definitive teachings.  They are not intended to be as definitive, or final, or decisive.  If I were blessed with the gift of utter reliability, this wouldn't necessarily imply that I must speak with absolute decisiveness in everything I say.  I might make a positive declaration intended to settle a particular question for all time.  And if I did that, in this hypothetical scenario, it would require acceptance as definitive.  It would be irreformable.  But if I said something like, "X is true, or at least this is the right and best position to hold at this time given the current state of our knowledge," my statement would still be completely reliable, but it is obviously less than final or definitive.  If you chose to rely on my statement, you would hold it as certain that, right now, you ought to hold opinion X, but you wouldn't believe that it could never happen that the "state of knowledge" could change in the future to the point that X would no longer be the right and best position to hold.  There would be two foolish extremes to avoid--on the one hand, attributing to my statement more than I intended and so holding as definitive what is non-definitive, and, on the other hand, refusing to accept my statement as far as it goes according to my intention.  In relying on my statement, you could never go wrong.  Even if that statement became obsolete in the future, you would never have been led into embracing any error by relying on it, for the reliability of a statement which allows for certain changing circumstances is not impugned if those circumstances should happen to change.

So the non-definitive teaching of the Church is, as far as it goes, free from error and utterly reliable.  The faithful are required to assent to it, to the extent and in the form required by the intention of the magisterial teacher as that intention is manifested in what is said, how it is said, etc.  It is not necessarily irreformable, but it is reliable as far as it is intended to go.  It partakes of the Church's infallibility in a sense broader than, but nevertheless just as real as, that which pertains to definitive teaching.

Conclusion

The utter, unfailing reliability of the Church's non-definitive teaching is evident from the language used by the Church to describe this teaching, as we have seen in the many quotations provided above.  Non-definitive teaching has "divine assistance."  It carries with it the "authority of Christ."  "A]ll acts of the Magisterium derive from the same source, that is, from Christ who desires that His People walk in the entire truth."  Its purpose for which it is granted divine assistance is to lead us to truth and help us avoid error.  The very fact that it is binding on the faithful and requires their assent implies necessarily its utter reliability, for Christ, "who desires that His People walk in the entire truth," will not bind anyone to error.  Non-definitive teachings "are set forth in order to arrive at a deeper understanding of revelation, or to recall the conformity of a teaching with the truths of faith, or lastly to warn against ideas incompatible with those truths or against dangerous opinions that can lead to error."  It does not therefore lead people away from a true understanding of revelation or lead them into error.  Propositions contrary to non-definitive teachings are categorized as "erroneous" or, if they are practical and prudential as opposed to doctrinal, as "rash and dangerous" and "not able safely to be taught," and they are subject to penalty if obstinately persisted in.  It is true to say of the ordinary teachings of popes as found in encyclical letters that "he who heareth you heareth me," and when the Pope passes judgment on a subject in his ordinary magisterium it "cannot be any longer considered a question open to discussion among theologians."  Non-definitive magisterial teaching is inherently reliable so that we should not subject it to our own private judgment and disagree with it merely because "the validity of the given teaching is not evident or upon the opinion that the opposite position would be the more probable."  We must, rather, trust it implicitly over our own private judgment.  Assent to non-definitive teaching "cannot be simply exterior or disciplinary but must be understood within the logic of faith and under the impulse of obedience to the faith."  Such assent is "distinct from the assent of faith, [but] is nonetheless an extension of it."  That is, we trust in non-definitive magisterial teaching for the same fundamental reason we trust in the Church's definitive teaching--because we acknowledge that all magisterial acts carry the authority of Christ and the protection and assistance of the Holy Spirit, so that our response to the teachings of the Magisterium, even non-definitive teachings, is an aspect of our faith in Christ himself.  Christ will not require his people to submit their judgment to and trust implicitly anything that could be erroneous, for he will not betray the trust he requires of his people.

The unfailing reliability of non-definitive magisterial teaching is also evident from the larger context of Catholic doctrine with regard to the general reliability and authority of the Church, which we looked at towards the beginning of this article.  The teaching of the Magisterium--whether of the bishops as a whole in communion with the Pope or of the Pope by himself--is the final authority in matters of faith and morals.  "It is this Magisterium's task to preserve God's people from deviations and defections and to guarantee them the objective possibility of professing the true faith without error."  "By a 'supernatural sense of faith' the People of God, under the guidance of the Church's living Magisterium, 'unfailingly adheres to this faith.'"  The Apostolic See of Rome "before all others . . . has the duty of defending the truth of the faith, so if any questions arise concerning the faith, it is by her judgment that they must be settled."  "Indeed, their apostolic teaching was embraced by all the venerable fathers and reverenced and followed by all the holy orthodox doctors, for they knew very well that this See of St. Peter always remains unblemished by any error, in accordance with the divine promise of our Lord and Savior . . ."  Those fathers "referred to this Apostolic See those dangers especially which arose in matters concerning the faith. This was to ensure that any damage suffered by the faith should be repaired in that place above all where the faith can know no failing."  "For in the Apostolic See the Catholic religion has always been preserved unblemished, and sacred doctrine been held in honor."  "This gift of truth and never-failing faith was therefore divinely conferred on Peter and his successors in this See" so that "the tendency to schism is removed and the whole Church is preserved in unity, and, resting on its foundation, can stand firm against the gates of hell."  The Magisterium in general and the papacy in particular are protected from every error.  They are utterly reliable.  The faithful cannot go wrong and cannot be led into any error by relying on their teaching.  This could not be the case if any binding magisterial teaching was not completely protected from error.  If the Magisterium, in either its definitive or its non-definitive teaching, could issue teachings intended as binding on the Church that were in error, the faithful, in such a case, would be required by their faithfulness to the truth of God to resist and dissent from such teachings and to refuse obedience to the magisterial command to embrace and follow such teachings.  The faithful would need to defend the revelation of God against the defection and doctrinal corruption of the Magisterium.  Can anyone seriously maintain that such a situation could fall within the purview of the Church's teachings regarding the Magisterium's general reliability?  In such a case, rather than being a sure protection against error as the Church says it always is, magisterial teaching would be the cause of error.  Instead of protecting against schism by unifying everyone in the truth, it would be the cause of schism by putting the faithful into a position where they would be morally required to oppose the teaching of the authentic teachers.

And lastly, the unfailing reliability of non-definitive magisterial teaching is evident from the very logic of Catholic epistemology.  The question that should be asked of those who wish to refuse assent to binding non-definitive magisterial teaching is this:  Why do you accept any teaching of the Church?  You say you accept the definitive teaching of the Church.  You accept the creeds, the dogma of the Immaculate Conception, etc.  Why?  "Because the Church teaches that definitive magisterial teaching is infallible."  But that same Church tells you to accept her non-definitive teaching as well.  If the Magisterium can intend a teaching as reliable and binding and yet can be wrong about that, how do you know that same Magisterium is not wrong when it teaches that the doctrine of the Immaculate Conception is infallible dogma?  Why do you believe the Magisterium when it tells you that definitive teachings in general are infallible, or that there is a distinction between non-definitive and definitive teachings, or anything else the Magisterium teaches?  The underlying foundation of any confidence in any magisterial teaching can only be belief in the absolute and universal reliability of magisterial teaching in general.  If the Magisterium says, "You should believe that X is definitively true," and you respond to this by saying, "Yes, I submit to that and believe that X is definitively true because you say so," when the same Magisterium then says, "You should believe that Y is non-definitively true," it is utterly inconsistent to respond to this by saying, "No, I refuse to believe you on this point."  It is inconsistent to put implicit trust in the Magisterium when it teaches X but to refuse such implicit trust when it teaches Y.  Consider, as an analogy, Scriptural authority.  If someone says, "I accept John 3:16 as true on the grounds that the Bible teaches it," it would inconsistent for that same person to say, "I refuse to accept Romans 6:1 as true even though the Bible teaches it."  So the dissenter cannot have his cake and eat it too.  He can refuse to believe the Church when she tells him that her non-definitive, official teaching is to be accepted, but then he will have no basis to put implicit trust in the Church when she tells him that her definitive teaching is to be accepted as definitive.  If he chooses to subject the Church's non-definitive teaching to his own private judgment, to be accepted or rejected according to the conclusion of his own independent evaluation, he will have to do this with her definitive teaching as well, which will lead him to a non-Catholic epistemology like that of Martin Luther, who was not impressed by the authority of popes or councils but made his own private interpretation of Scripture the final authority in faith and morals.  (See here for an excellent article showing how modern "conservative" dissenters treat Tradition much like Protestants treat Scripture--as a norm to be interpreted finally not by the Church but by their own private judgment.  And see here for a similar argument in the form of a fictional dialogue.)  Or, on the other hand, he can trust the Church implicitly when she tells him that her definitive teaching is to be accepted as definitive; but if he does that he will also, to be consistent, have to believe the Church when she tells him to accept her non-definitive teaching.  He will have to give up his whole general attitude of dissent and submit his private judgment to the Church's teaching, in whatever form and to whatever degree she intends to bind him to it.  If the Church allows a range of opinion on a subject, well and good.  He can follow his judgment within that range.  But when the bishops or the Pope put forward a teaching on a particular subject and he cannot show that they allow disagreement on that subject, he will have to submit to that teaching with his mind and his will.  He will then find himself in unity with all the faithful in the truth of God.

Are We Allowed to Criticize and Reject the Pope's Teaching?

Throughout history, there have always been Catholics who have wanted to dissent from the teaching of the popes.  Today, we see this attitude in theological "liberals" who do not like some of the "old fashioned" teaching of the Church, particular with regard to sexual matters.  We also see this attitude today in theological "conservatives" who dislike some of the more recent teaching of popes since Vatican II, some of whom find especially distasteful some of the recent teaching from Pope Francis with regard to pastoral discipline for those in irregular "marriage" unions as well as his recent teaching on the death penalty.  Some theologians have argued that dissent from papal teaching in certain circumstances is allowed by the Church.  One of the main magisterial documents they have appealed to is a document from the Congregation for the Doctrine of the Faith called Donum Veritatis ("On the Ecclesial Vocation of the Theologian").

In light of this, I think it would be helpful to take a brief look at the Church's rules when it comes to criticism and dissent from papal teaching, with some focus on the teaching of Donum Veritatis.  This will be just a brief look here, as I have done a more thorough look at this subject elsewhere.

The basic teaching on this matter is expressed in the Vatican II document Lumen Gentium:

Among the principal duties of bishops the preaching of the Gospel occupies an eminent place.(39*) For bishops are preachers of the faith, who lead new disciples to Christ, and they are authentic teachers, that is, teachers endowed with the authority of Christ, who preach to the people committed to them the faith they must believe and put into practice, and by the light of the Holy Spirit illustrate that faith. They bring forth from the treasury of Revelation new things and old,(164) making it bear fruit and vigilantly warding off any errors that threaten their flock.(165) Bishops, teaching in communion with the Roman Pontiff, are to be respected by all as witnesses to divine and Catholic truth. In matters of faith and morals, the bishops speak in the name of Christ and the faithful are to accept their teaching and adhere to it with a religious assent. This religious submission of mind and will must be shown in a special way to the authentic magisterium of the Roman Pontiff, even when he is not speaking ex cathedra; that is, it must be shown in such a way that his supreme magisterium is acknowledged with reverence, the judgments made by him are sincerely adhered to, according to his manifest mind and will. His mind and will in the matter may be known either from the character of the documents, from his frequent repetition of the same doctrine, or from his manner of speaking.  (Second Vatican Council, Lumen Gentium, #25)

Here we see that the Church requires assent to all her teaching, whether that teaching comes from the universal episcopate of all the bishops or from the head of the bishops, the Pope, the Bishop of Rome.  With regard to papal teaching, we must adhere to all of it according to the Pope's intention in giving it to us, his "manifest mind and will."

The Church has reiterated this in her Code of Canon Law as well:

Can. 750 §1. A person must believe with divine and Catholic faith all those things contained in the word of God, written or handed on, that is, in the one deposit of faith entrusted to the Church, and at the same time proposed as divinely revealed either by the solemn magisterium of the Church or by its ordinary and universal magisterium which is manifested by the common adherence of the Christian faithful under the leadership of the sacred magisterium; therefore all are bound to avoid any doctrines whatsoever contrary to them. 

§2. Each and every thing which is proposed definitively by the magisterium of the Church concerning the doctrine of faith and morals, that is, each and every thing which is required to safeguard reverently and to expound faithfully the same deposit of faith, is also to be firm-ly embraced and retained; therefore, one who rejects those propositions which are to be held definitively is opposed to the doctrine of the Catholic Church. . . . 

Can. 752 Although not an assent of faith, a religious submission of the intellect and will must be given to a doctrine which the Supreme Pontiff or the college of bishops declares concerning faith or morals when they exercise the authentic magisterium, even if they do not intend to proclaim it by definitive act; therefore, the Christian faithful are to take care to avoid those things which do not agree with it. . . . 

Can. 754 All the Christian faithful are obliged to observe the constitutions and decrees which the legitimate authority of the Church issues in order to propose doctrine and to proscribe erroneous opinions, particularly those which the Roman Pontiff or the college of bishops puts forth.

We see here that Church teaching, whether from the bishops as a whole or from the Pope, can be definitive or non-definitive.  Both forms of teaching are to be adhered to.  Both are binding.

This teaching was elaborated upon by the Congregation for the Doctrine of the Faith in a document written up as a commentary on a required profession of faith promulgated by Pope John Paul II ("Doctrinal Commentary on the Concluding Formula of the Professio fidei").  In this document, the Congregation defines more particularly the nature of the non-definitive teaching of the Church and the form of adherence required with regard to it:

10. The third proposition of the Professio fidei states: "Moreover, I adhere with religious submission of will and intellect to the teachings which either the Roman Pontiff or the College of Bishops enunciate when they exercise their authentic Magisterium, even if they do not intend to proclaim these teachings by a definitive act." To this paragraph belong all those teachings­ on faith and morals - presented as true or at least as sure, even if they have not been defined with a solemn judgment or proposed as definitive by the ordinary and universal Magisterium. Such teachings are, however, an authentic expression of the ordinary Magisterium of the Roman Pontiff or of the College of Bishops and therefore require religious submission of will and intellect.18 They are set forth in order to arrive at a deeper understanding of revelation, or to recall the conformity of a teaching with the truths of faith, or lastly to warn against ideas incompatible with these truths or against dangerous opinions that can lead to error.19 

A proposition contrary to these doctrines can be qualified as erroneous or, in the case of teachings of the prudential order, as rash or dangerous and therefore 'tuto doceri non potest'.20 . . . 

As examples of doctrines belonging to the third paragraph, one can point in general to teachings set forth by the authentic ordinary Magisterium in a non-definitive way, which require degrees of adherence differentiated according to the mind and the will manifested; this is shown especially by the nature of the documents, by the frequent repetition of the same doctrine, or by the tenor of the verbal expression.38

Again, we see that the non-definitive teachings of the Church, just like the definitive teachings, require the assent of the faithful.  We are not allowed to dissent from them.  However, there are "degrees of adherence differentiated according to the mind and the will manifested."  The intention of the bishops or the Pope, as they manifest this intention in their teaching, determines the degree of adherence required in any particular case.  This is of particular importance to emphasize, because this is where those who wish to dissent erroneously from papal teachings often go wrong.  They recognize, correctly, that there are degrees of adherence required of various magisterial teachings.  As they say, and as we'll see more in a moment, this does indeed mean that we can criticize and even disagree with some of things the bishops and the Pope say.  But the real question is, Who determines the degree and form of assent required in any particular case?  The erroneous dissenters make themselves and their own judgment the determining factor in deciding what they are required to assent to and to what degree they are required to assent.  But the Church teaches that it is the bishops and the Pope who make that determination.  We don't get to subject the teachings of the bishops and the Pope to our own judgment and decide, even against their intentions and requirements, what we will agree with and what we will disagree with.  We must assent to their teaching according to their manifest mind and will.

As I mentioned, erroneous dissenters sometimes appeal to the document from the Congregation for the Doctrine of the Faith called Donum Veritatis to justify their dissent.  (There is a kind of logical absurdity in this endeavor, actually--to appeal to Church teaching in order to justify refusing to submit to Church teaching.  If one can subject Church teaching to one's own judgment and reject what one doesn't approve of, why trust the judgment of Donum Veritatis to confirm one in this practice?)  So let's see what Donum Veritatis says about when we can criticize or disagree with Church teaching:

23. When the Magisterium of the Church makes an infallible pronouncement and solemnly declares that a teaching is found in Revelation, the assent called for is that of theological faith. This kind of adherence is to be given even to the teaching of the ordinary and universal Magisterium when it proposes for belief a teaching of faith as divinely revealed. 

When the Magisterium proposes "in a definitive way" truths concerning faith and morals, which, even if not divinely revealed, are nevertheless strictly and intimately connected with Revelation, these must be firmly accepted and held.(22) 

When the Magisterium, not intending to act "definitively", teaches a doctrine to aid a better understanding of Revelation and make explicit its contents, or to recall how some teaching is in conformity with the truths of faith, or finally to guard against ideas that are incompatible with these truths, the response called for is that of the religious submission of will and intellect.(23) This kind of response cannot be simply exterior or disciplinary but must be understood within the logic of faith and under the impulse of obedience to the faith. 

24. Finally, in order to serve the People of God as well as possible, in particular, by warning them of dangerous opinions which could lead to error, the Magisterium can intervene in questions under discussion which involve, in addition to solid principles, certain contingent and conjectural elements. It often only becomes possible with the passage of time to distinguish between what is necessary and what is contingent. 

The willingness to submit loyally to the teaching of the Magisterium on matters per se not irreformable must be the rule. It can happen, however, that a theologian may, according to the case, raise questions regarding the timeliness, the form, or even the contents of magisterial interventions. Here the theologian will need, first of all, to assess accurately the authoritativeness of the interventions which becomes clear from the nature of the documents, the insistence with which a teaching is repeated, and the very way in which it is expressed.(24)

We see here the same reiteration of the various forms of Church teaching we saw earlier.  We also see here the same requirement of assent to all Church teaching, whether definitive or non-definitive.  We do see that sometimes "a theologian may, according to the case, raise questions regarding the timeliness, the form, or even the contents of magisterial interventions."  So some criticism and disagreement may be allowed.  But notice two things:  1. The rule is submission.  Unless one can prove a basis for disagreement, there must be submission.  The burden of proof is on those who advocate disagreement.  2. The forms and degrees of criticism and disagreement allowed are determined by "the authoritativeness of the interventions which becomes clear from the nature of the documents, the insistence with which a teaching is repeated, and the very way in which it is expressed."  This the same language we've seen before.  How do we know when and to what extent we can criticize?  We must look to the manifest mind and will of the magisterial teachers.  Donum Veritatis does not alter or even add anything to what we've already seen.  It reaffirms that we are to submit to all Church teaching, definitive or non-definitive, to the extent and in the form required according to the intention and requirements of the magisterial teachers.  Once again, we are not allowed to decide for ourselves, even against the intentions and requirements of Church teachers, when and how much criticism and disagreement is permitted to us.

In conclusion, then, we are indeed allowed at times to criticize and even disagree with the teaching of the bishops of the Church and of the Pope.  But, if we want to do this, we must first prove that the bishops or the Pope have allowed disagreement in any particular case.  If we cannot do this, we must submit and assent to the teaching.  If the evidence says that the bishops or the Pope intend their teaching to be binding and accepted by the faithful, then the faithful are required to submit.  In this way, truth and unity will be preserved and error and schism avoided as we all agree in mind and will with what the Church is teaching us.

This gift of truth and never-failing faith was therefore divinely conferred on Peter and his successors in this See so that they might discharge their exalted office for the salvation of all, and so that the whole flock of Christ might be kept away by them from the poisonous food of error and be nourished with the sustenance of heavenly doctrine. Thus the tendency to schism is removed and the whole Church is preserved in unity, and, resting on its foundation, can stand firm against the gates of hell.  (Vatican I, Chapter 4, Section 7, as found on the EWTN website.  "The translation found here is that which appears in Decrees of the Ecumenical Councils ed. Norman Tanner. S.J. The numbering of the canons is however found in Tanner's text.")

For more, see here.