589. The results of disobeying an erroneous conscience are as follows:
(a) He who disobeys an invincibly erroneous conscience, is guilty. Example: The child who refuses to tell a lie when he thinks he ought to do so because it has been commanded, is guilty of disobedience.
(b) He who disobeys a vincibly erroneous conscience, is also guilty. Example: Caius promises to tell a lie to help another party. The doubt occurs whether or not this is lawful, and he takes no pains to settle it correctly, but decides offhand that a promise must be kept. When the time comes, Caius becomes alarmed and does not keep his promise, lest he get into trouble. He is guilty.
590. If a conscience which was vincibly erroneous in its origin is here and now invincibly erroneous, the acts that result from following such a conscience are to be judged as follows:
(a) They are materially evil in themselves and formally evil in their cause. Example: Titus, who intends to take a position in which he will have to advise others, foresees that later on he may make mistakes costly to others, as a result of his present lack of sufficient study. He secures the position, and tries to make up for former neglect of study, but on one occasion injures a patron by wrong advice which he would not have given, had he worked more faithfully as a younger student. The wrong advice is objectively sinful in itself, as being an injury; it is subjectively sinful in its cause, as being the result of negligence which foresaw what might happen.
(b) The acts in question are not formally evil in themselves. Example: Titus was formally guilty of injury to others at the time he foresaw what would happen on account of his negligence; he was not formally guilty at the time he did the injury, because he had tried meanwhile to repair his negligence and was not conscious of his ignorance.
591. The kinds of sin committed in consequence of an erroneous conscience are as follows:
(a) Sin committed by following a vincibly erroneous conscience is of the same gravity and species as the act for which the conscience is responsible, but the ignorance is an extenuating circumstance. Example: He who blinds his conscience so that it decides in favor of grave calumny, is guilty of mortal sin against justice; but he is less guilty than if he had sinned without any permission from conscience.
(b) Sin committed by disobeying an invincibly erroneous conscience is of the gravity and species apprehended by the conscience. Example: A person who tells a small lie, thinking it a mortal sin against charity, is guilty of the malice he understands to be in his act.
(c) Sin committed by disobeying a vincibly erroneous conscience is of the species that was perceived. Example: Caius who did not live up to his promise of telling a lie, after he had decided that to keep his word was the right thing to do, was guilty of a breach of promise. As to the gravity of sin against a vincibly erroneous conscience, it is always the same as that apprehended by the conscience, unless what is seriously wrong is culpably mistaken for what is only slightly wrong. Examples: If Caius, just referred to, thought that his desertion of his friend inflicted a grave injury, he was guilty of grave sin. A person who persuades himself by vain reasonings that complete intoxication does not differ in gravity from incipient intoxication, is nevertheless guilty of the greater malice, if he puts himself in the former state; for his wrong opinion cannot change the fact, and his culpable ignorance cannot excuse him.