I. On the Nature of Conscience

How manyfold is the acceptance of conscience? - Conscience can be taken in two ways, physically and morally. Conscience physically considered pertains to Psychology and to Logic, according as it is considered either precisely insofar as it is a cognitive faculty of returning upon its own acts, or precisely insofar as it is an instrument of attaining truth. But conscience taken morally belongs both to Moral Theology and to Moral Philosophy. Therefore here the discussion will be only of conscience morally considered. We shall speak first of the intrinsic nature of this moral conscience, then of its various divisions.

What is the intrinsic nature of moral conscience? - Law regulates human actions in order to their moral honorableness or shamefulness by means of conscience. For in order that it regulate them, it must be applied to the action to be effected here and now, so that it may be seen whether such an action is commanded, prohibited, permitted by law, or counseled; from which application a judgment is then formed concerning such or such an action, to be effected or omitted here and now, and this practical judgment is conscience. Therefore conscience is nothing other than the practical judgment by which we pronounce a thing to be done or omitted here and now as good or evil; and this after the manner of a precept, or counsel, or simple permission.

Therefore in order that we may form this conscience, we make a syllogism. In this syllogism the major proposition states the law generally. But the minor proposition of the same syllogism compares the action which we wish to do here and now with the law. Finally the consequent, from the conformity or deformity of such or such an action with the law affirmed in the premises, pronounces that such or such an action is to be effected here and now as good, or to be omitted as evil; and this judgment or dictate is called conscience. Dictate, for to dictate is to command, to ordain; and conscience is like an interior law which binds man. Judgment, since as dictate it concerns only those things which ought to be done or omitted, but as judgment it also concerns those things which can be done or omitted. Therefore conscience differs altogether from synderesis, which is the natural habit of the first principles of things to be done, which natural principles are of natural right. S. Th. 1. p. q. 79. a. 12. 13, 1. 2. q. 76. a. 1, De Verit. q. 16. a. 1, q. 17. a. 1. 5, 2. D. 24. q. 1. a. 4, q. 2. a. 4; Suarez tr. 3. d. 12. s. 1; L. 1. 1. n. 1. 2.

What are antecedent and consequent conscience? - Moral conscience, whose nature we have already described, and about which we are speaking at present, is called antecedent conscience, to be distinguished from another moral conscience, which is called consequent; and this is the one which reports that an action already done was morally good or evil. But to avoid cavils about that former conscience, namely that it should not be called conscience, since it bears judgment about a thing not done but to be done, for conscience reports internal facts, we briefly note that usage has already obtained that it be so called. But usage in this matter is a sufficient reason. Now the formal goodness or malice of human acts is to be taken not from consequent conscience, but from antecedent conscience. Hence those who study moral theology are sometimes deceived, because they think that after gaining knowledge they had sinned in many things; since they lacked that knowledge when they acted, and were then acting in good faith. The same should be said of the uneducated and all others who, after hearing a sermon, after reading a pious book, begin to be involved in anxiety as regards past operations. - S. Th. 1. p. q. 79. a. 3, De Verit. q. 17. a. 1. 2.

What are the divisions of moral conscience? - If in that syllogism which must be formed in order that conscience may be had, the major proposition, or law, always stood with evident certainty, and the minor proposition, or that this or that action is contained in the law, also always stood with evident certainty, there would be only one conscience, certain and right conscience. But since both the law and the application of the law often must be gathered by the force of difficult reasoning, hence there are various species of conscience.

Therefore it is divided: 1. Into right and erroneous conscience. Right conscience is that which dictates what is true; erroneous, that which dictates as true what is false. Erroneous conscience is either vincibly or invincibly such, according as the error morally could and ought to have been avoided, or morally could not have been avoided. 2. Into certain, probable, doubtful, strict, lax, and scrupulous conscience, according as it is founded on a certain, probable, doubtful, stricter, laxer, or altogether empty motive. Conscience only subjectively certain, namely one which is thought to be such, and therefore with certainty taken more broadly, as also probable and doubtful conscience, can be objectively right or erroneous. But scrupulous, strict, and lax are brought back to erroneous conscience. For without sufficient reason, the scrupulous conscience fears sin where there is no sin; the lax bends judgment in favor of liberty, either to avoid the law simply, or to lessen its obligation; but the strict affirms either an obligation which is not present, or one more grave than actually exists. Suarez t. 3. d. 12. s. 2;

S. Th. 1. 2. q. 19. a. 3, a. 6 ad 2, Quodl. 3. a. 26.