637. Remedies for a bad conscience and means for cultivating a good conscience are as follows:
(a) The remote causes of a bad conscience are in the will itself. A person judges wrongly often because he is wrong in himself, wrong in his intentions and purposes with regard to life as a whole, wrong in his attitude towards a particular line of duty, wrong in his lack of sincerity with himself. Hence, the correctives needed are a sincere love of God and of virtue, courage to wish the truth, and an honest examination of motives and actions: “The sensual man perceiveth not the things that are of the Spirit of God, but the spiritual man judgeth all things” (I Cor., ii. 14, 15).
(b) The immediate causes of a bad conscience are in the intellect. One judges wrongly because one clings in time of doubt to erroneous ideas or principles. The remedy, therefore, is to seek diligently for light through prayer, to study the lives and conduct of those who are models, to consult with the prudent and the conscientious. The bad conscience says to God: “Depart from us, we desire not the knowledge of Thy ways” (Job, xxi. 14); but the good one says: “Teach me Thy justifications. Thy testimonies are my delight, and Thy justifications my counsel” (Ps. cxviii. 12, 24).
638. Signs of a Good Conscience.—(a) Extraordinary holiness is not necessary before one may consider one’s conscience good, for there are degrees of goodness. If, therefore, a person’s external life is directed by the duties of his state, and his internal life, as far as he can judge, is free from serious guilt and guided by love of God and hatred of sin, he may safely regard his will as good. If sometimes he sins venially, this is not because he lacks a good conscience, but because he does not always follow it.
(b) Extraordinary diligence in studying one’s duties is not necessary before one may regard one’s conscience as good, for otherwise a heavier burden would be imposed than we can suppose God to intend. A person who is using all the means for obtaining religious instruction that are used by others in his position and who are conscientious, may safely regard himself as free from voluntary error. If sometimes he judges wrongly, the mistake will be involuntary and not due to a bad conscience. Of course, one whose conscience is not in vincible error may sin even mortally, not because his conscience is bad, but because he does not follow it.
639. The following are means for preserving and maintaining a good conscience: (a) we should judge our motives frequently with the severity with which we judge the motives of another (Rom., ii. 1), and as before God (I Cor., ii. 10); (b) we should measure our actions, not by the standards of the world, its maxims and examples, but by those of Christ (I John, ii. 15-17; III John, 11).
Art. 3: A CERTAIN CONSCIENCE
(_Summa Theologica_, I-II, q. 57, a. 5; II-II, q. 47, a. 9.)
640. As was said above, only that conscience is a safe guide which is not only good—that is, in agreement, as far as one’s efforts can secure this, with the external law—but also certain. A certain conscience is one which, without any prudent fear of erring, judges that a particular act is obligatory or unlawful, and hence here and now to be done or omitted.
641. Necessity of Certitude.—We must be sure we are right before we act; otherwise, we expose ourselves to the danger of sinning, and therefore commit sin (see 582). Hence, it is necessary to act with a certain conscience, and unlawful to act with an uncertain conscience. “If the trumpet give an uncertain sound, who shall prepare himself to the battle?” (I Cor., xiv. 8) may be accommodated to conscience. In Rom., xiv. 22, 23, the Apostle declares that he who acts with conviction is blessed, whereas he who acts in uncertainty is condemned. Examples: Sempronia doubts whether it is sinful to sew on Sunday; she is not sure, but has grave suspicions that sewing is servile work; if she goes ahead, she will be guilty of violating the law, as being willing to take the risk, and therefore the responsibility. Titus offers another a drink, being uncertain whether it has poison in it or not; he is guilty of sin, since he has no right to expose himself to sin and his neighbor to the danger of death.