About Ignatius Insight
  Who We Are
  Ignatius Press
  Ignatius Press catalogs
  Catholic World Report
  Homiletic & Pastoral Review
  IP Novels site
  IP Religious Ed blog
  IP Critical Editions

The Truth About Conscience | John F. Kippley | An excerpt from Sex and the Marriage Covenant

Print-friendly version

The importance of having correct ideas about conscience and a correct conscience cannot be overestimated. It is literally a matter of life-and-death importance. Adolf Eichmann, the director of Hitler's mass murder campaign against Jews and others whom Hitler deemed undesirable, provided the classic statement to show this importance when he argued in his defense: "I was following my conscience."

On the other hand, Dr. Bernard Nathanson stopped being one of the chief abortionists in the United States because he could no longer live with his conscience. A whole organization called Women Exploited by Abortion came into being to provide a voice for women who have had abortions but whose consciences led them to reject their past behavior and to witness against it.

There's a lot of planned confusion in some talk about conscience. You may hear about the "supremacy of conscience" and the need to "respect the consciences of others". There is a grain of truth in such phrases, but what about the person who collects door-to-door for a charity-but then keeps it all for himself, and, when apprehended, says he was just following his conscience? Examples could be multiplied to illustrate the need for clarity about conscience.


Etymologically, the word "conscience" comes from two Latin words–cum (with) and scientia (knowledge)–thus meaning "with knowledge". You can say that a judgment of conscience is a judgment made with knowledge; but while that's true, it's not very helpful except to raise further questions about the sources and the truth of that knowledge.

What conscience isn't

However, this very basic understanding of conscience–a judgment made with knowledge-enables us to realize that conscience is not a feeling though you may feel bad after going against your conscience–at least at first.

Also, conscience is not simply an inner voice in the sense of some sort of organ or direct communication from God. However, I do not want to rule out all intuitive knowledge. I think many people are gifted with the intuitive knowledge that certain actions are wrong, but as I and, I am sure, countless others have discovered, it is extremely easy to rationalize away the promptings of a conscience based upon intuitive knowledge, especially as a young person. "If this were really wrong, my parents or teachers would have told me; but they haven't (of course, I haven't asked); so it must be okay . . ." Furthermore, as I have listened to individuals and heard of whole primitive cultures that have at least initially rejected unnatural means of birth control, I remain convinced about the reality of intuitive knowledge in this area. The pressures of contraceptive propaganda, however, illustrate the need for a more certain and concrete form of knowledge, which I will discuss later.

In saying that conscience is not simply an inner voice in the sense of a direct communication from God, I do not want to rule out the role of the Holy Spirit in communicating with an individual person. Whenever you pray for guidance as to whether you should do this good thing or that good thing, you are asking for that sort of divine, communication. Examples abound: the single person should pray for guidance concerning a vocation to marriage, the priesthood, or religious life. The unwed pregnant mother should pray for guidance as to whether she should raise the child herself or give her baby up for adoption. Parents should pray for guidance as to whether to seek another pregnancy.

What I am ruling out is the appeal to conscience as some sort of direct divine communication exempting the person from the Commandments or other binding obligations. The single person shouldn't pray for guidance as to whether he should follow a career of prostitution. The well-instructed Catholic unwed expectant mother shouldn't need to pray for guidance about abortion. Spouses shouldn't need to pray for guidance about entering a spouse-swapping arrangement. In all of these cases, God has made it abundantly clear what is immoral, and it is wrong to pretend he hasn't already given us that guidance. In all of these cases the prayer must be for the strength to keep the Commandments. Knowledge is not virtue; we absolutely need the grace of God to keep the Commandments, and we also need to pray for that grace.

What conscience is

Catholic theology uses the word "conscience" in three complementary ways: capacity, knowledge, and practical judgment.

Vatican II teaches that "conscience is man's most secret Core, and his sanctuary. There he is alone with God whose voice echoes in his depths." [1] Pope John Paul II used that quotation and noted: "Conscience, in fact, is the 'place' where man is illuminated by a light which does not come to him from his created and always fallible reason, but from the very Wisdom of the Word in whom all things were created." [2]

Terms such as "secret core", "his sanctuary and "the place" indicate that the subject is man's capacity to form judgments about right and wrong.

The above quotation from Pope John Paul II (which is repeated in the next chapter in the fuller context of a papal address to theologians) also points at God's role in enlightening the human conscience, and that's what we've called the knowledge element of conscience. Discourse about the formation of conscience also indicates the knowledge aspect of conscience.

Practical judgment.
Conscience, however, is more than knowledge. We cannot live in an ivory tower of knowledge alone. We have to bring that knowledge to bear upon matters that demand a decision such as: I will take an answer from my fellow student's exam, or I will not look. I will let the baby live, or I will not. I will or will not enter the seminary. We will or will not attempt to enlarge our family.

That's why Catholic moral theology teaches that conscience is a practical judgment that I must do this good or avoid that evil.

As a practical judgment, it is not just an intellectual matter; rather it is a practical decision that "this is good, and I must do it" or "this is evil, and I must avoid it."

As a judgment, it is based on the knowledge you have about the good or evil of a proposed action.

Correct and erroneous conscience

You can have a correct or erroneous conscience depending upon the value of the knowledge on which you base your judgment. Who are we to say that Eichmann was lying when he said he was following his conscience? But you want to scream, "Your conscience was all wrong!"

Maybe Eichmann actually came to believe the Hitler line about an Aryan super-race. If so, he had an erroneous conscience, and you rightly want to say, "But that's no excuse. You had an obligation to form a correct conscience."

Some people like to talk about an "informed" conscience, but that's not helpful until you supply the adverbs "rightly" or "incorrectly"; and that brings you back to the standard terms–" correct" and "erroneous" "conscience".

Objective and subjective elements

refers to the action you arc considering in its objective moral reality. The action will be right or wrong in objective reality regardless of how you or anyone else judge it. For instance, in the order of objective moral reality, it is either wrong or not wrong to kill at) unborn baby. It can't be both. For your judgment to be correct, it must conform to the objective reality about the morality of such an act. Otherwise your judgment of conscience is in error.

elements refer to the person who makes the judgments of conscience. It refers to some elements known only to God, such as whether the person incurs the guilt of sin for doing what is objectively a wrongful action. If the person says, "I know now that what I did was, in objective reality, an evil thing, but I didn't know at the time it was wrong", that person would have to ask himself, "But was my ignorance vincible or invincible?"

• Vincible ignorance
is ignorance you can and should overcome with the means at your disposal. There is a saying in American law that "ignorance of the law excuses no one." In terms of moral guilt or innocence that phrase applies only to vincible ignorance because as human beings we are obliged to make a reasonable effort to find out the truth that can be found. Vincible ignorance means that a person had at least some clue that an action might be morally wrong in objective reality but did not take reasonable steps to follow up on that clue. The same would hold true if he had some clue that a certain action might be morally obligatory in objective reality.

Invincible ignorance refers to ignorance that a person in his circumstances cannot be expected to overcome. The person simply has no clue that a certain action or a way of life is, in objective reality, morally obligatory for its performance (if it is a good act) or its avoidance (if it is a bad act). A person with utterly no contact with Christianity cannot overcome his ignorance about Christ.

• Certain and doubtful
refer to subjective states of the person. If you are certain about the morality of some action, you may or you must follow your conscience depending upon the type of action. For example, if you are certain it is wrong to donate infected blood to a blood bank and you are certain you have infected blood, then you must follow your conscience and not give blood. On the other hand, if you are certain that it is not wrong to donate healthy blood and you have healthy blood, then you may or should donate your blood.

To be "certain" means that you are convinced by reasons that make sense to you here and now. It does not mean that you can absolutely rule out at least a slim possibility that you might be making a mistake about the moral right or wrong of the action you are now considering. For example, let's take an action that's not burdened with the grave matter of mortal sin. Mr. Smith discovers mud all over the floor by the back door. He sees Johnny, his third-grade son, and his friends playing in the yard, with mud all over their shoes. So he deduces that it was Johnny and his friends. He confronts Johnny, who denies responsibility. But Mr. Smith knows that lately Johnny has been telling lies whenever he gets caught disobeying one of the house rules. So he administers a discipline of having Johnny write 1 00 times, "I must always tell the truth." That night he learns that his wife was the mud tracker. At the time he was certain enough to take the sort of action he did; he had the kind of certainty that parents need for managing a home and administering discipline for actions of which they are not a direct eyewitness. He may apologize to Johnny, and he may feel good that he confined the discipline to a non-corporal punishment. He can also tell himself that he did the best he could with the information that was available to him at the time, including his conviction that discipline for young children should be administered promptly.

If you are doubtful about the morality of some action, you shouldn't act, but instead you should get advice and clarify your conscience. The wisdom of the axiom "you should not act on a doubtful conscience" is easily seen in the common example about the hunter who hears a lot of noise in the bushes but isn't certain if it's an animal or a fellow hunter. That happened to me the only time I ever went deer hunting-after struggling up a steep, brushy knoll on all fours I raised my head and looked into my friend's rifle barrel! Fortunately, he clarified his doubtful knowledge by waiting. As I wrote at the beginning of this chapter, conscience decisions can literally be matters of life or death.


The obligation to follow your conscience is fundamental to being human, for it is simply another way of saying we must do good and avoid evil. It is such a basic principle that you simply can't talk about morality with someone who would say that he was not obliged to follow his conscience, that he was not obliged to do good and to avoid what he knows el is evil. Germain Grisez has said it well: "The duty to follow one's conscience is neither one specific responsibility among others nor a supreme responsibility which perhaps could conflict with and nullify others. For no matter what in particular one ought to do, one ought to follow one's conscience. That is so because the duty to follow conscience is reducible to the duty to do what is morally good." [3]

Grisez notes that the statement "One ought to do what is morally good" is "true by definition" and as such doesn't call for discussion. However, he says it can still be "interesting and informative to say: 'One ought to follow one's judgment of conscience' because it implies that [you] ought to follow [your] judgment of conscience in the face of a temptation not to do so" (emphasis added). [4]

The difference between "may", "should", and "must"

All three of these words are used in talk about conscience.

You may follow your conscience.
You must follow your conscience.
You should do this or avoid that.

The difference between may and must stems from both the (1) nature of the action and (2) the certainty of the knowledge you can attain.

The nature of the action.
Negative obligations can be universal and absolute so that there are no exceptions. Such prohibitions are called universal negative absolutes, and the Church's teaching against abortion and marital contraception are examples of such universal negative absolutes. "Thou shalt never directly kill an unborn baby." "Thou shalt never engage in marital contraception." At the level of the properly formed Catholic conscience, such teaching becomes "I must never abort a baby; I must never use or recommend marital contraception." At the level of responding to here-and-now temptation, the person with a properly formed conscience will make the practical judgment of conscience: "I must not abort this baby; I must not give in to this temptation to use or recommend marital contraception." The strength of "must" here means that what is forbidden is the grave matter of mortal sin.

Having rejected unnatural methods of birth control, you still have other decisions. Must you let the babies come as they may or may you use natural methods of family planning? You search for Catholic teaching, and you find out that the Church teaches that marriage is for family, that married couples are called to be generous in the service of life, but that no specific numbers of children are given. You discover that you would need an extremely serious reason to choose not to have any children, and that you need a sufficiently serious (even though not "extremely serious") reason to postpone pregnancy and/or limit your family size. Furthermore, although I am not aware of any specific teaching on the matter of temporary spacing, I think you can draw a proportion between the duration of the spacing intended and the seriousness of the reason required. It would not require much of a reason to decide upon two-year spacing between babies because that appears to be a very natural norm with fully natural or ecological breastfeeding. On the other hand, I think that to decide on four-year spacing would require sufficient "physical or psychological conditions of husband and wife or ... external conditions". [5]

Forced with a "family planning" decision, you may judge that here and now you have sufficient human resources to take care of another baby and the family you already have. You may or even should choose to let the babies come as they may. On the other hand, you may have sufficient reason to judge that you may or should choose to postpone pregnancy through natural family planning.

As an example of the latter case, let us imagine that you have had four babies in the first five years of your marriage, the wife is exhausted, you are just barely able to pay your bills, etc. You reach the conclusion that you have very serious reasons for postponing pregnancy and that you should practice natural family planning. In fact, your "should" is so strong that you feel it is a "must". I use the term "should" here because if you do not practice NFP but instead both mutually and freely agree to allow more babies to come as they will, you are not entering the area of the grave matter of mortal sin.

"Should" works the other way too, Let us imagine that you have four or five children, well spaced out, no big problems, and you are still in your mid-to-late thirties. You feel drawn to have another baby; you can't really think of a serious reason not to, but you're fearful. All the "what ifs" start bothering you. What if the next baby isn't healthy and requires all sorts of care? What if the husband loses his job? Etc. What if after seeking counsel you think you should but you're afraid? That sort of "should" is also not the "must" whose violation necessarily involves the grave matter of serious sin. Furthermore, as a perceived positive obligation, it does not have the universality of a universal negative absolute.

These cases of "should" illustrate the need for a prayerful dialogue with God concerning matters that go beyond the clear universal negative absolutes of the Church's moral teaching.

A good counselor might affirm to the first couple the Church's teaching that parenthood involves caring for and educating one's children, not simply begetting them. To the second couple he might affirm the Church's teaching about generosity in the service of life and the need for prayer to have more trust in God. But he should encourage both couples to seek from God what He wants. God may be calling one couple to develop further sexual self-control and non-genital marital courtship. The Lord may be calling another couple to an extra measure of trust and generosity. However, these are conclusions that cannot be arrived at by a third-party counselor; they need to be the result of prayer.

The certainty of your knowledge.
If in your search for the truth you discover that the Church has clear and specific teaching on the subject of concern, then you have certain knowledge and are obliged to form your conscience accordingly. On the other hand, on some matters you may find that there is an absence of clear and specific teaching and that competent theologians, faithful to the whole official teaching of the Church, are, in fact, divided into two or more schools of thought on the matter. Or the teaching may be clear, but there are differences about its application to concrete cases. In the absence of clear and authoritative teaching on the part of the magisterium, you may-indeed, must-form your conscience according to the line of reasoning that seems best to you. This is what is known as the theological theory of probabilism. Such a theory does not say you can do anything that comes to mind; rather it is intended to offer you more than one well-considered opinion to assist the formation of your conscience.

Note well: the theory of probabilism does not apply to the birth control issue because the Church has clear and authoritative teaching against all forms of marital contraception. In the years 1964 to 1967, some theologians were arguing that the teaching was no longer certain and that therefore probabilism could be applied. However, the issuance of Humanae Vitae eliminated all such theorizing and wishful thinking. Even those who believe the teaching is wrong have to admit that it is clear and authoritative.


Since we have the obligation to make and to follow the judgment of conscience, we also are obliged to make sure that our judgments are correct. We have the right and the duty to do what is right; we also have the right and a duty to find out what is the right thing to do. Another way of saying this is that we have a fundamental obligation to live according to the truth, and that means we have a fundamental obligation to seek the truth.

Those statements are so obvious and fundamental no thinking person of goodwill can deny them. What is controversial in our day is this: Where do you find out what is the right thing to do? When there are differences in teaching, when the pop columnists in a secular culture say one thing and the Catholic Church teaches something else, who should I believe teaches the truth about the way that leads to eternal life?

I believe that God has given us a firm and certain way to know what is morally right and wrong. Jesus Christ taught, "I am the way and the truth and the life" (Jn 14:6), and he established a historical and visible Church upon Simon, whose name he changed to Peter, or Rock, in order to keep his teaching alive and available for all men of all times. Therefore I believe that the correct conscience is the one conformed to the formal teaching of the Roman Catholic Church. The reasons for that statement of faith and the reasons I believe there is no other easily accessible source of the full truth about moral right and wrong are spelled out in the next chapter.


[1] Vatican Council II, Gaudium et Spes (On the Church in the Modern World), (December 7, 1965), no. 16.

[2] John Paul II, "The Diligent Search for Truth Requires the Teaching of the Magisterium", L'Osservatore Romano (December 19-26, 1988): 6.

[3] Germain Grisez, "The Duty and Right to Follow One's Judgment of Conscience", Homiletic and Pastoral Review 89:7 (April 1989): 10.

[4] Ibid.

[5] Paul VI, Humanae Vitae (Of Human Life), (July 25, 1968), no. 16.

John F. Kippley has been active in the family planning movement since 1968 and co-authored The Art of Natural Family Planning with his wife, Sheila. Recently they wrote an on-line manual—Natural Family Planning, launched a website (www.NFPandmore.org), and founded NFP International. Mr. Kippley has also written Marriage Is For Keeps and many articles, some of which are available at their website.

If you'd like to receive the FREE IgnatiusInsight.com e-letter (about every 2 to 3 weeks), which includes regular updates about IgnatiusInsight.com articles, reviews, excerpts, and author appearances, please click here to sign-up today!


World Wide Web


Place your order toll-free at 1-800-651-1531

Ignatius Press | San Francisco
Web design under direction of Ignatius Press.
Send your comments or web problems to:

Copyright 2018 by Ignatius Press

IgnatiusInsight.com catholic blog books insight scoop weblog ignatius