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The Catholic Teaching on Conscience

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Ahead of the print release of the important treatise from our contributing editor, Dr. Peter Kwasniewski, True Obedience in the Church: A Guide to Discernment in Challenging Times, we present two pieces today on the Catholic understanding of conscience.

As you may know, the term “conscience” has been used by Liberal heretics since the turmoil after Vatican II and Humanae Vitae to overturn Catholic doctrine on contraception (among other things). Led by heretical bishops, priests and professors in open revolt against Paul VI’s encyclical, they cited Vatican II in order to justify their heresy:

“That the Catholic people took to heart the elevation of conscience in Dignitatis Humanae is reflected in their resounding rejection – even while remaining Catholics in good standing – of Humanae Vitae[.]”[1]

To this day, priests have been malformed in the Catholic doctrine on conscience, and continue to promote errors on conscience which contribute to many Catholics practicing contraception without any knowledge of the fact that they are objectively committing sin. They have cited Vatican II on this error, to the great peril of souls and the loss of faith in little children. This provoked the John Paul II pontificate to issue Veritatis Splendor (perhaps his greatest encyclical), but because the “medicine of mercy” overpowered the “charitable anathema,” the heretic wolves continued to destroy the faith of children and are now restored to power under the current pontificate of the Dictator Pope.

This issue comes to play especially when we consider the hyperüberultramontanism of the false spirit of Vatican One. This false spirit says that whatever the pope decides, even if it be against reason, Tradition, or your well-formed conscience, must be accepted and received with blind (read: irrational) obedience. This is Jesuit obedience or Monastic obedience, incumbent upon the few Catholics under such vows. But not the obedience which obliges the vast majority of Catholic faithful, lay and priest alike.

But what makes resistance of Liberal heretics to Paul VI – in the name of conscience – different from TLM (and Novus Ordo!) Catholics’ resistance to Francis – in the name of conscience?

The answer is Catholic obedience according to the Catholic understanding of conscience.

The Liberal heretics wanted to impose heretical obedience according to a heretical conscience. When they found that Paul VI was promoting their cause (as with Carroll’s above erroneous teaching citing Vatican II), they stressed hyperüberultramontanism: obedience to the pope always and everywhere! As soon as the pope produced Humanae Vitae, these Liberals switched to defending their heresy in the name of conscience. The Liberals did the same thing when they found that Leo XIII was on their side, just the same as they are doing now with Pope Francis (for example, in the Instrumentum Laboris for the Ordinary Synod on the Family, which undermined the intrinsic evil of contraception by means of errors about conscience, para. 137).

But even a pope does not have the authority to overturn Catholic obedience and Catholic conscience. The pope is, rather, appointed as the defender of Catholic obedience and conscience.

Catholic obedience will be explicated in the aforementioned treatise by Kwasnkiewski. For now, we print the following treatise on conscience from the Dominican school. This is from Fr. Dominic Prümmer, widely considered one of the best moralists before Vatican II. His three volume treatise Manuale Theologiae Moralis is still a standard textbook in the few seminaries which seek to uphold Tradition against what Ratzinger said was a “collapse of moral theology” following Vatican II (sadly, few seminaries even form priests with enough Latin proficiency to read Prümmer at all).

Luckily, Prümmer’s shorter work, Handbook of Moral Theology, has been translated into English. His treatise on conscience from this work is excerpted below. Note especially his distinctions regarding doubt and certainty and the duty to form your conscience. The entire work is available for free Online or Digitized (full index, incomplete text)Digitized (full text, no index) or if you can find an old copy, in Print.

In our second piece on conscience later today we will examine what St. John Henry Newman said against the false spirit of Vatican One and in the name of conscience.


T. S. Flanders
St. John Chrysostom



135. Definition. Leaving on one side other meanings of the word, conscience is here understood for the judgment or dictate of the practical intellect deciding from general principles the goodness or evil of some act which is to be done here and now or has been done in the past.

1. Conscience is a judgment or dictate of the practical intellect, since it is not a power or a habit but an act, that is, the application of knowledge to an individual fact, and this application is a judgment or dictate of the practical intellect. Therefore, conscience is not an act of the speculative intellect or of the will.

2. Conscience derives its judgment from general principles, since it presupposes as true the general principles of faith and of natural reason, and applies these to an individual case. Therefore, conscience does not pass judgment on the truths of faith and of reason but decides whether the act to be done (or which has been done) is in conformity with existing just law.

3. Conscience decides the goodness or evil of some act which is to be done here and now (or has been done). Conscience is the subjective standard of morality and therefore an act is subjectively good or bad according to the judgment of conscience. The proper and primary function of conscience is to pass judgment on an act which is to be done, but it may also pass judgment on acts which have been performed already.

136. Scholium. Difference between conscience, moral habit (synderesis), moral science, prudence, natural law.

1. Moral habit (synderesis) is the habitual practical knowledge of the first principles whose proper act is to decide in a general way that good must be done and evil avoided, whereas conscience decides in an individual case what is to be done or omitted. The moral habit of man never errs, conscience may do so.

2. Moral science deduces objective conclusions from the first principles, whereas conscience is something subjective which may or may not agree with moral science.

3. Prudence is a virtue and therefore a habit; conscience on the other hand is an act. Sometimes, however, an act of prudence coincides with conscience.

4. Natural law embraces the objective principles of morality, whereas conscience uses these principles to decide whether an act should be performed or whether it should be omitted.

137. Kinds.

1. In regard to the act considered by conscience, conscience is either antecedent if it precedes the act to be performed, or consequent if it passes judgment on acts already performed. Antecedent conscience either commands, or forbids, or counsels, or permits the performance of an act; consequent conscience either approves of the act performed, causing spiritual joy, or disapproves of the act, thus causing remorse.

2. In regard to its conformity with the eternal law, conscience is true (correct) when it deduces correctly from true principles that some act is lawful; it is false (erroneous) when it decides from false principles considered as true that something is lawful which in fact is unlawful. An erroneous conscience is further distinguished into: a) a scrupulous conscience, which for useless and almost ridiculous reasons judges or, rather, fears that an act is evil when in fact it is not; b) a perplexed conscience, which sees sin both in the performance and in the omission of some act; c) a lax conscience, which judges on insufficient grounds that there is no sin in the act, or that the sin is not so grave as it is in fact; the worst form of this type of conscience is the hardened conscience, which as the result of a long-established habit of sinning regards all – or at least some – sins to be of little importance; d) a pharisaic conscience, which minimizes grave sins but magnifies matters of little importance in the same way as the Pharisees behaved.

3. In regard to the act of assent, conscience is either certain, when without any prudent fear of error it firmly decides that some act is either lawful or unlawful, or probable, when it judges that some act is probably lawful or unlawful, or doubting, when it hesitates to pass judgment on the moral character of the act.

A doubting conscience understood in this latter sense is really a contradiction in terms. Conscience is defined as essentially a judgment or dictate of the intellect, whereas doubt signifies a suspension or denial of judgment. Therefore, it would be preferable to cease speaking of a doubting conscience and to substitute the resolution of moral doubt. Some modern authors identify a doubting conscience with a probable conscience.


138. First Principle. Everyone is obliged to use serious care to possess on all occasions a true conscience.

The reason is obvious: conscience is the proximate norm of morality which must act as the guide for the whole of man’s moral life. Now it is of supreme importance that his moral life be guided by a correct and not by a false standard. – The means to be used for obtaining a true conscience are: a) a careful knowledge of the laws which govern our moral life; b) taking wise counsel; c) prayer to the Father of light; d) removal of obstacles to a true conscience, chief amongst which is the obscurity resulting from unforgiven sin.

139. Second Principle. Everyone is obliged to follow his conscience whether it commands or forbids some action, not only when it is true but also when it is in invincible error.

There is a reason for the use of the two words commands and forbids, for if conscience permits or merely counsels some line of action there is no strict obligation to follow it. It is patently obvious why we must obey a true conscience, and the reason for man’s obligation to follow an invincibly erroneous conscience is that failure to do so would mean that he was acting contrary to the subjective norm of morality and was therefore committing sin. Thus, for example, a person who is convinced that he ought to tell a lie in order to save his friend from some danger is bound to tell the lie; in so doing he does not commit formal sin. Anyone who thinks that today is a fast day, although as a matter of fact it is not, and in spite of his conviction does not observe the fast, commits formal sin.

140. Third Principle. It is not permissible to follow conscience when it is in vincible error no matter whether it commands or forbids some action; on the other hand, one cannot act contrary to such a conscience; the error must be corrected before any action is taken.

As will be proved later, a certain conscience alone is the lawful guide of morality. A vincibly erroneous conscience is not a certain conscience and consequently a man who acts while his conscience is in that state exposes himself to the danger of sin. – If a man’s conscience is in error through his own fault, then he must correct that error by taking suitable means to discover the truth; if his efforts fail he must refrain from action, but if even this is impossible then he must choose what appears to be the safer course.


141. The causes of a lax conscience are numerous:

1) bad education and evil company – all too evident from daily experience;

2) violent disorderly passions, which usually cloud the intellect and prevent it from making a correct judgment;

3) a life of vice, which causes spiritual blindness or at least shortsightedness.

142. The remedies for a lax conscience are:

1) devout and assiduous prayer to God, the Father of light;

2) sacramental Confession where the penitent receives grace and correct instruction;

3) removal of the causes of laxity.


143. 1. A perplexed conscience is one which fears sin both in the performance and in the omission of some action. For example, a sensitive person whose duty it is to care for a sick person thinks that it is sinful not to assist at Mass on a feast day, and yet fears that he sins against charity by leaving the sick person alone in the house.

Rule to be followed. If the person suffering from a perplexed conscience is able to suspend action or to seek advice, then that without doubt is the course to be followed; if on the other hand this is morally impossible, then he should choose that which seems to him the less of two evils; if he is not able to decide which is the less evil, he is free to decide either to act or to refrain from action since no one is obliged by the impossible and no one commits sin when under the influence of force.

If the state of perplexity arises through previous negligence, e.g., if a confessor through culpable lack of knowledge does not know whether to absolve a penitent or not, what has been said already above in reference to vincible and culpable ignorance applies here.

144. 2. A scrupulous conscience is a state of groundless fear rather than the judgment of a healthy mind. Such a conscience is a torment both to the penitent and to the confessor. Great care must be exercised in distinguishing it from a tender conscience which carefully avoids all sin, even the smallest. Therefore, it is essential to be familiar with the signs of a scrupulous conscience.

Signs of a scrupulous conscience: a) excessive anxiety about previous confessions; b) protracted accusations of irrelevant details; c) stubbornness which refuses to accept the decisions of the confessor.

The causes of a scrupulous conscience are sometimes (although rarely) supernatural, namely God or the devil; more frequently they are natural and are either moral, such as the excessive avoidance of human company, conversation with timorous persons, hidden pride, and so on, or physical, namely a pathological condition of the brain or heart or nerves or intestines.

The remedies for scruples are:

a) the removal of their causes, for which the aid of an experienced doctor is often necessary;

b) perfect obedience to a wise director;

c) healthy recreation and manual or spiritual work to distract the mind from the scrupulous thoughts;

d) fervent and assiduous prayer to God, the Father of light and the source of peace.


We shall consider: 1) the certain conscience; 2) the doubting conscience, or rather, the course of action to be followed in a state of moral doubt.

Art. 1. The Certain Conscience

145. Kinds. As stated already, a certain conscience judges without any prudent fear of error that an act is either lawful or unlawful.

Moral certainty – and this is the type of certainty to be considered here – is divided as follows:

a) it is said to be perfect (strict) when it excludes prudent doubt, and imperfect (wide) when some slight reasons militate against the truth of a decision which is founded on serious motives.

b) Moral certainty is speculative when the intellect considers the truth of some matter in an objective manner without any direct reference to a practical case; it is practical when it is concerned with an act to be done here and now.

c) Direct moral certainty is based on intrinsic principles which clearly reveal the moral character of the act; indirect moral certainty is derived from what are called reflex principles, which we shall discuss later.

146. Principle. a) Only a certain conscience (whether the certainty is direct or indirect) is a correct guide to moral behavior, and b) to act lawfully imperfect certainty is ordinarily sufficient.

The reason for the first part of the principle is that the man who acts without being morally certain that his act is lawful commits sin by exposing himself unnecessarily to the proximate danger of formally offending God.

The second part rests on the fact that sometimes it is impossible to obtain anything more than imperfect certainty regarding our actions, and no one is bound to do the impossible. The same truth is evident from the third proposition condemned by Alexander VIII: “It is not permitted to follow a (probable) opinion or among the probables the most probable.”[1] Even the most probable opinion is not absolutely certain but is certain only in the wide sense of the term. Therefore, if one is permitted to follow a most probable opinion, absolute certainty is not always required, and certainty in the wide sense is sufficient.

Art. 2. The Doubting Conscience, or, Moral Doubt

147. Kinds. Doubt understood in the strict sense is the suspension of the intellect’s assent and judgment in reference to a proposition, and consequently it is opposed not only to certainty but also to suspicion and opinion in which there exists a genuine intellectual assent, although imperfect and accompanied by the fear of error. When in doubt, the mind is like the arm of a balance which remains horizontal, inclining neither to one side nor to the other. – Together with St. Thomas[2] earlier authors used to distinguish three steps leading to the firm assent of the intellect: 1) the state of doubt where no assent exists; 2) the states of opinion and suspicion in which the intellect gives an imperfect assent; 3) science and faith where there exists a firm assent, without any fear of error. – Recent authors usually prefer to speak of only two stages: a certain assent without any fear of error (certainty) and uncertain assent accompanied by the fear of error (doubt).

Kinds of doubt. 1. The mind may be doubtful about the existence of some law (dubium juris) or of some particular fact (dubium facti).

2. Doubt is said to be positive when the fear of error is based on grave reasons; it is negative when the fear of error rests on slight reasons.

3. Doubt is either speculative or practical. The first turns on the objective morality of a human act irrespective of its present performance or omission. Such speculative doubt exists in controversial questions when moralists argue on either side, e.g., whether an irregular will binds in conscience or not. Practical doubt is concerned with the morality of an act about to be performed here and now – for example, whether it is lawful to read this dangerous book.

148. Principle. No one is allowed to perform an act while in a state of positive practical doubt.

The reason should be evident from what has been said already. For if certainty in the wide sense of the word is required for lawful action, it is not lawful to act while in a state of positive practical doubt, since by so doing one exposes oneself to the immediate danger of committing formal sin. If, therefore, a man doubts the lawfulness of some action he must either refrain from acting or remove his practical doubt. There are two possible ways of removing the doubt, one direct, the other indirect. The direct method consists in diligently searching after the truth until at length certainty is attained. If this direct method is impossible, then the doubt may be removed indirectly by so-called reflex principles.

149. Reflex or indirect principles are general directions which directly and of themselves do not prove the truth of the matter under investigation but nevertheless reflect, so to speak, their own clear light on the obscure practical doubt and dispel the darkness of that doubt while the act is being performed. The more important reflex principles are the following:
1. A doubtful law has no binding force.
2. In doubt one must stand by presumption.
3. In doubt possession is nine-tenths of the law.

1. A doubtful law has no binding force whenever the doubt concerns the lawfulness of an act and not its validity. Whatever may be said about the truth of this principle which is fiercely attacked by some theologians, all modern theologians are agreed that it cannot be applied in the following cases:
a) when the doubt concerns the validity of the Sacraments;
b) when the doubt concerns something which is absolutely necessary for salvation; so, for example, when there is risk of losing eternal life, the safer opinion must be followed;
c) when the question involves an established right of a third party. Thus, for example, a judge would not be justified in giving judgment on the basis of a probable opinion while refusing to follow what is certainly the more probable opinion.

2. When in doubt one must stand by presumption. This seems the most useful of all the principles and was already to be found expressed in the Decretals of Gregory IX. All other reflex principles rest on this and when rightly used it seems sufficient for solving all practical doubt.

3. In doubt possession is nine-tenths of the law. This principle forms the basis for the theory of Equiprobabilism and is known in brief as the principle of possession. In its application to matters of commutative justice the principle is most certain and is found in the Decretals of Gregory IX, but it has also been extended to other matters, although its practical application is not devoid of difficulty and is frequently misused.

[1] James Carroll, “The Beginning of Change,” in Norman Tanner, S. J., ed., Vatican II: The Essential Texts (New York: Image, 2012), 23.

[2] DZ 1293.

[3] See Summa Theologiæ, II-II, q. 2, a. 1.

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