Article — Merkelbach, Summa Theologiae Moralis
Article III: On Vincibly Erroneous Conscience
St. Thomas, in the same places.
62. Vincibly erroneous conscience is that which, from false principles vincibly reputed true, judges something in particular to be licit or illicit which is not really such. It arises from insufficient diligence in inquiring concerning the morality of the act, so that by moral diligence it can be laid aside but from carelessness is not laid aside; this carelessness is voluntary, whether indirectly from negligence, while someone adverts to the obligation of inquiring further, or even directly from contempt: it is voluntary, namely, in the mode by which ignorance can be voluntary. Hence, in the same way as ignorance, according to the diverse grades of the voluntary, erroneous conscience can be distinguished as simply vincible, crass or supine, and affected.
Thus a judge who, while adverting that he does not sufficiently know the cause, nevertheless gives sentence and does not will to acquire more perfect knowledge, rashly exposes himself to the danger of erring.
63. Thesis. Vincibly erroneous conscience is not a rule of acting prudently and licitly, as being naturally suited to expose one to the danger of formally sinning, but regularly must be laid aside by a more diligent inquiry into truth, so that he who follows it when it permits, and he who acts against it when it commands or prohibits, sins.
It is proved: He who acts against such a conscience when it commands or prohibits does what he judges to be evil and thus sins; he who follows it when it permits does that which he cannot prudently judge to be truly licit and good because he has negligently inquired and judged concerning the morality of his act; and thus he operates rashly and exposes himself to the proximate danger of formally sinning and sins. "He sins by acting against it, by choosing an evil which he judges to be evil; but he sins by acting according to it because, since he ought and can conquer the error, by not laying it aside he operates rashly." St. Alphonsus, Moral Theology, book I, n. 4.
It is confirmed: 1) He who adverts that further inquiry must be made concerning the truth of the honesty of his act and does not do it commits a sin of precipitation against prudence in counsel; whence with such imprudence he is not able to establish a rule of acting prudently. Cf. Jn. IX, 41; XV, 24.
- He who acts conformably to a vincibly erroneous conscience, in fact acts against law; nor is he excused, because ignorance of the law is here and now voluntary.
Hence he who, so that he may help his neighbor, erroneously but vincibly judges that he must lie or steal, while at the same time adverting to the obligation of inquiring further into the truth, sins whether according to conscience he steals, or against conscience he does not steal. And nevertheless it does not follow that he is simply perplexed or necessarily sins, because he can do a third thing, by which, when done, he does not fall into sin, namely, lay aside the erroneous conscience: just as a priest who is bound to celebrate Mass and is in sin, sins by not celebrating, and also by celebrating.
64. Sense of the doctrine. - Vincibly erroneous conscience is said not to be a rule of acting but ordinarily and regularly to be laid aside, because it is naturally suited to cause sin, namely while it permits evil or prohibits a good that must be done. For one exception is given: if there were question of an act certainly good in itself which someone erroneously thought to be commanded, or of an indifferent act certainly not commanded which he erroneously thought to be prohibited: then he could follow the erroneous conscience, nor would he be bound to lay it aside, because in the case no danger of sinning would be present.
Thus if someone from voluntary error thought that one must fast or hear Mass, or that hunting is prohibited on Sunday.
65. Observations. - 1. In order that someone sin by acting against vincibly erroneous conscience, the act must be free. Hence he does not sin:
a) who, imprisoned, omits to hear Mass if it is not celebrated in the prison, while nevertheless he thinks that he sins;
b) the scrupulous person who thinks that dishonorable or blasphemous thoughts are always sins, while he is unable to make them not enter his mind;
c) likewise one who altogether involuntarily suffers distractions in prayer, or nocturnal pollution in sleep, or a girl who suffers menstrual flow, while nevertheless he or she thinks it to be a sin.
- Vincibly erroneous conscience is in no sense right or true, not even practically and according to a reflex judgment, because, with sufficient inquiry lacking, the agent cannot say in truth, "all things diligently considered," nor sincerely judge the act to be good. Whence such a conscience is simply erroneous and also practically false.