Thomas Aquinas - Summa Theologica, Part I-II (Pars Prima Secundae)

I answer that, Since conscience is a kind of dictate of the reason, for it is an application of knowledge to action, as was stated in the First Part (Q. 19, A. 13), to inquire whether the will is evil when it is at variance with erring reason, is the same as to inquire "whether an erring conscience binds." On this matter, some distinguished three kinds of actions: for some are good generically; some are indifferent; some are evil generically. And they say that if reason or conscience tell us to do something which is good generically, there is no error: and in like manner if it tell us not to do something which is evil generically; since it is the same reason that prescribes what is good and forbids what is evil. On the other hand if a man's reason or conscience tells him that he is bound by precept to do what is evil in itself; or that what is good in itself, is forbidden, then his reason or conscience errs. In like manner if a man's reason or conscience tell him, that what is indifferent in itself, for instance to raise a straw from the ground, is forbidden or commanded, his reason or conscience errs. They say, therefore, that reason or conscience when erring in matters of indifference, either by commanding or by forbidding them, binds: so that the will which is at variance with that erring reason is evil and sinful. But they say that when reason or conscience errs in commanding what is evil in itself, or in forbidding what is good in itself and necessary for salvation, it does not bind; wherefore in such cases the will which is at variance with erring reason or conscience is not evil.

But this is unreasonable. For in matters of indifference, the will that is at variance with erring reason or conscience, is evil in some way on account of the object, on which the goodness or malice of the will depends; not indeed on account of the object according as it is in its own nature; but according as it is accidentally apprehended by reason as something evil to do or to avoid. And since the object of the will is that which is proposed by the reason, as stated above (A. 3), from the very fact that a thing is proposed by the reason as being evil, the will by tending thereto becomes evil. And this is the case not only in indifferent matters, but also in those that are good or evil in themselves. For not only indifferent matters can receive the character of goodness or malice accidentally; but also that which is good, can receive the character of evil, or that which is evil, can receive the character of goodness, on account of the reason apprehending it as such. For instance, to refrain from fornication is good: yet the will does not tend to this good except in so far as it is proposed by the reason. If, therefore, the erring reason propose it as an evil, the will tends to it as to something evil. Consequently the will is evil, because it wills evil, not indeed that which is evil in itself, but that which is evil accidentally, through being apprehended as such by the reason. In like manner, to believe in Christ is good in itself, and necessary for salvation: but the will does not tend thereto, except inasmuch as it is proposed by the reason. Consequently if it be proposed by the reason as something evil, the will tends to it as to something evil: not as if it were evil in itself, but because it is evil accidentally, through the apprehension of the reason. Hence the Philosopher says (Ethic. vii, 9) that "properly speaking the incontinent man is one who does not follow right reason; but accidentally, he is also one who does not follow false reason." We must therefore conclude that, absolutely speaking, every will at variance with reason, whether right or erring, is always evil.

Reply Obj. 1: Although the judgment of an erring reason is not derived from God, yet the erring reason puts forward its judgment as being true, and consequently as being derived from God, from Whom is all truth.

Reply Obj. 2: The saying of Augustine holds good when it is known that the inferior authority prescribes something contrary to the command of the higher authority. But if a man were to believe the command of the proconsul to be the command of the emperor, in scorning the command of the proconsul he would scorn the command of the emperor. In like manner if a man were to know that human reason was dictating something contrary to God's commandment, he would not be bound to abide by reason: but then reason would not be entirely erroneous. But when erring reason proposes something as being commanded by God, then to scorn the dictate of reason is to scorn the commandment of God.

Reply Obj. 3: Whenever reason apprehends something as evil, it apprehends it under some species of evil; for instance, as being something contrary to a divine precept, or as giving scandal, or for some such like reason. And then that evil is reduced to that species of malice. ________________________

SIXTH ARTICLE [I-II, Q. 19, Art. 6]

Whether the Will Is Good When It Abides by Erring Reason?

Objection 1: It would seem that the will is good when it abides by erring reason. For just as the will, when at variance with the reason, tends to that which reason judges to be evil; so, when in accord with reason, it tends to what reason judges to be good. But the will is evil when it is at variance with reason, even when erring. Therefore even when it abides by erring reason, the will is good.

Obj. 2: Further, the will is always good, when it abides by the commandment of God and the eternal law. But the eternal law and God's commandment are proposed to us by the apprehension of the reason, even when it errs. Therefore the will is good, even when it abides by erring reason.

Obj. 3: Further, the will is evil when it is at variance with erring reason. If, therefore, the will is evil also when it abides by erring reason, it seems that the will is always evil when in conjunction with erring reason: so that in such a case a man would be in a dilemma, and, of necessity, would sin: which is unreasonable. Therefore the will is good when it abides by erring reason.

On the contrary, The will of those who slew the apostles was evil. And yet it was in accord with the erring reason, according to John 16:2: "The hour cometh, that whosoever killeth you, will think that he doth a service to God." Therefore the will can be evil, when it abides by erring reason.

I answer that, Whereas the previous question is the same as inquiring "whether an erring conscience binds"; so this question is the same as inquiring "whether an erring conscience excuses." Now this question depends on what has been said above about ignorance. For it was said (Q. 6, A. 8) that ignorance sometimes causes an act to be involuntary, and sometimes not. And since moral good and evil consist in action in so far as it is voluntary, as was stated above (A. 2); it is evident that when ignorance causes an act to be involuntary, it takes away the character of moral good and evil; but not, when it does not cause the act to be involuntary. Again, it has been stated above (Q. 6, A. 8) that when ignorance is in any way willed, either directly or indirectly, it does not cause the act to be involuntary. And I call that ignorance "directly" voluntary, to which the act of the will tends: and that, "indirectly" voluntary, which is due to negligence, by reason of a man not wishing to know what he ought to know, as stated above (Q. 6, A. 8).

If then reason or conscience err with an error that is voluntary, either directly, or through negligence, so that one errs about what one ought to know; then such an error of reason or conscience does not excuse the will, that abides by that erring reason or conscience, from being evil. But if the error arise from ignorance of some circumstance, and without any negligence, so that it cause the act to be involuntary, then that error of reason or conscience excuses the will, that abides by that erring reason, from being evil. For instance, if erring reason tell a man that he should go to another man's wife, the will that abides by that erring reason is evil; since this error arises from ignorance of the Divine Law, which he is bound to know. But if a man's reason, errs in mistaking another for his wife, and if he wish to give her her right when she asks for it, his will is excused from being evil: because this error arises from ignorance of a circumstance, which ignorance excuses, and causes the act to be involuntary.