Treatise I: On Conscience

St. Thomas, Eth., VI, 1, 2; 3 D. 33, q. 1; 1.2, q. 19, a. 5; q. 57, a. 5; St. Alphonsus, Theol. mor., 1; H. Ap., 1; John of St. Thomas (ed. Vives), VI, q. 31, disp. 22; Sylvius-Maurus, in Eth., VI; Suarez, in 1.2, tr. 3, disp. 12, sect. 1, 2, 4; the moral works of more recent writers: Lehmkuhl, Aertnys, Noldin, Tanquerey, Gopfert, etc.; Beaudouin-Gardeil, de Consc.; Bouquillon, Theol. mor. fund. (ed. 3).

11. Definition. Conscience is a practical judgment or dictate of reason, by which we judge what here and now is to be done as good, or avoided as evil (I, 2).

It is called: a practical judgment, namely one which directs the one operating in acting; by which we judge, that is, by which without any fluctuation of mind we affirm; what here and now, that is, in the individual case, and with all circumstances considered; is to be done, that is, ought or can be done; as good, or avoided as evil; by these words is expressed the formal respect under which the agent exercises his judgment concerning acts to be placed. For he does not judge concerning the utility or facility of an action or omission, but concerning its relation to the moral law, namely whether it is according to it, against it, or beside it (1.2, q. 19, a. 5).

12. Division. 1. Conscience, by reason of the acts to which it is referred, is either antecedent or consequent. Antecedent conscience is that which precedes human acts, so as to compose them according to the norm of right. Consequent conscience is a judgment concerning past acts; it approves or disapproves, praises or condemns with remorse; it is not conscience properly so called.

All the more, that habit by which the one who is endowed with it promptly obeys the dictate of conscience, and is called a conscientious man, is not conscience properly so called.

Antecedent conscience obtains various names according to its various office. When it judges what is to be avoided as evil, it is called prohibiting conscience; when it judges what is to be done as a good of precept, it is called prescribing conscience; finally, when it judges that something has been left to free choice, it is called permitting conscience; and it is also named counseling conscience, when it declares a thing to be better and of counsel.

2. By reason of the object, conscience is true or erroneous; by reason of the subject, it is certain or doubtful. These will soon be explained more fully. Conscience, whether true or certain, is prohibiting, or prescribing, or permitting or counseling, as was said above.

13. That the nature of conscience may be better known, it is pleasing to note the following.

I. Conscience is an act of the practical intellect.

1. It is an act, not a power or a habit; for conscience is said as though knowledge with another, because it is the application of knowledge or notice to a particular action: but the application of knowledge to something is made by some act. Besides, conscience can be put aside and is easily changed, which cannot be said of a power (St. Thomas, P. I, q. 79, a. 13).

2. It is an act of the intellect, not of the will; for it goes before the will, and signifies to it what in a particular case is good or evil, which evidently pertains to the cognitive faculty.

3. It is an act of the practical intellect. For according to the twofold respect under which the intellect is considered, it is called either speculative or practical. The speculative or theoretical intellect is that which rests in the contemplation of its object, whether the matter concerns fact (that is, the existence, nature, properties, or effects of a thing), or right (that is, law, or its disposition, extension, or interpretation). The practical intellect is that which extends or applies knowledge to work (ibid., a. 11). Cf. Cajetan, 1.2, q. 57, a. 5; Beaudouin, work cited; John of St. Thomas, Logica, P. II, q. 1, a. IV.

From these things it is understood what, in things operable, is a speculative judgment and what is a practical judgment. A speculative judgment, when operations are in question, is that by which the intellect declares that the thing objected to it, in itself, is objectively good or evil, for example, this war is just or unjust. A practical judgment is that by which the intellect decrees that the same thing, the present circumstances considered, here and now, subjectively, can or ought actually to be chosen or rejected, for example, it is lawful for me to fight in this war.

II. Although synderesis, moral science, and prudence concur in forming conscience, nevertheless conscience differs from them.

It differs from synderesis. Synderesis is not an act but a habit naturally instilled, by which we know the first principles of things to be done, for example: good is to be done, evil is to be fled; God is to be worshiped; what you do not wish to be done to you, do not do to another (St. Thomas, place cited, a. 12).

It differs from moral science. This also is a habit of the speculative intellect, but acquired, and is concerned with general conclusions deduced from first principles in this or a similar way: synderesis brings forth the first principle: evil is to be fled; science subsumes: theft is evil, and concludes: therefore it is not lawful to steal. Therefore moral science is concerned with the objective and material morality of an act; but conscience with the subjective and formal morality of the same.

It differs also from prudence. Prudence is a habit of the practical intellect, and has a broader scope than conscience. For prudence, besides those parts which it obtains in forming the dictate of conscience, especially in weighing the peculiar circumstances of the fact, also inquires into the means suitable for attaining the end. Thus, for example, when a superior must correct some guilty person, conscience indeed declares the obligation of correcting; but prudence suggests how one must proceed, that the end, namely amendment, may be obtained (Billuart, de act. hum., Diss. 5, a. 1).

III. Conscience is a judgment concluding from two premises, whether the syllogism is made implicitly or explicitly. Synderesis or science furnishes the major premise, which declares the disposition of the law; the particular fact to which the application of the law must be made supplies the minor; prudence watches lest either be asserted rashly; the conclusion is the practical judgment which is called conscience. For example: A superior legitimately commanding must be obeyed. But this superior commands legitimately. Therefore he must be obeyed (St. Thomas, de Verit., q. 17, a. 2).

14. Order of things to be said. Conscience, as we intimated above, must, on the part of the object, be conformable to truth; but on the part of the subject, it must rest upon moral certitude. Whence there must be treated: 1. true conscience, and erroneous conscience opposed to it; 2. certain conscience, and doubtful conscience opposed to it. But since the question of solving doubts arising from the occurrence of probable opinions is of particular importance, it must be treated specifically. Hence: 3. probable conscience.