Chapter II. The Certain Conscience

CERTAINTY in general is a firm assent of the mind to something known, without the fear of mistake. In mathematics and in other branches of exact science we can often attain absolute certainty, which rests on the evident truth of the principles which are employed to arrive at it. For anyone who is capable of following the demonstration there can be no manner of doubt that the angles of a triangle are together equal to two right angles. In the science of morality we have frequently to be content with a lower degree of certainty than this; there is often some obscurity about the principles to be applied, and human acts are not the matter of necessary and unvarying law. We have to be content with what is called moral certainty; but this again is of various degrees. I am morally certain of the existence of Berlin, though I never saw the city. Any person who doubted of its existence would be thought to be insane. The grounds on which the judgement that Berlin exists are based are so many and so strong that they leave no room for prudent doubt in the matter. In such cases we have perfect moral certainty. In other cases I may be conscious that mistake is possible but not probable, as when a man has been condemned on evidence which has satisfied a jury of intelligent men. In such cases if there can be no prudent doubt about the justice of the verdict I have moral certainty of an imperfect but real kind. If I could not safely rely in guiding my conduct on such a degree of certainty, I should have to abstain from action altogether. Ordinarily greater certainty cannot be obtained in human affairs.

In order to act lawfully and rightly, I must have at least moral certainty of the imperfect kind that the proposed action is honest and right. This degree of certainty will be sufficient, for ordinarily no greater can be had, as we have just seen. It is also required for right action; for if I am not at least to this extent morally certain that my action is right, I am conscious that it may be wrong. In this case I am bound to pause, and satisfy myself that it is right before acting; for if I do not do so my will is ready to embrace what may be wrong I am ready to do the action whether it is in right order or not. But such a will is malicious; it is not firmly set on doing what is right; and sin is thereby committed.

A subjectively certain conscience then, which tells me without prudent doubt that the action is right, is required for lawful action; “‘ All that is not of faith is sin,” as St Paul says.¹ It will be sufficient if we have imperfect moral certainty, as we have seen.²

¹ Rom. xiv 23.

² St Thomas, 2-2, q. 70, a. 2.

If I have this imperfect moral certainty that my action is right, I am justified in acting, and if with such certainty my conscience tells me that I am bound to act, I must do so, even though my conscience be erroneous. For my action is morally good if my will be good. My will is good when it tends to a good object as represented by my intellect, not as it is in itself. But if my will follows my conscience and determines on what it prescribes, my will then tends to a good object as represented by my intellect and is a good will. So that even though my conscience be erroneous, I am justified in following it, and I am bound to follow it when it prescribes any action to be performed.¹ This is true whenever I have a certain conscience—that is, when I have no doubt or suspicion about the honesty of my action, even though my conscience be erroneous. If I were the wilful cause of my conscience being in error by not taking means to inform it correctly, then any objectively wrong action that I perform is voluntary in the cause, and so far imputable to me, but here and now I must follow my conscience.

I am said to be bound by my conscience because it compels me to follow it under pain of doing wrong, committing sin, and being exposed to the pangs of remorse. It binds me also in the name of God, whose will it makes known to me, It speaks, therefore, with the authority of God, it sternly bids me follow his behests, and it reproves me with the authority of a superior if I neglect to follow its promptings. As representing the will of God its authority is greater, as St Thomas teaches,² than that of any merely earthly superior. .4. The question as to whether in any particular case a person acted with an erroneous conscience is a question of fact, which only he and God can decide. Still, following approved theologians, we may make use of certain presumptions drawn from the nature of things and from experience. It may be admitted that ignorant and dull people may have an invincibly erroneous conscience concerning the malice of merely internal sins committed in thought only; but we should except efficacious desires to do what is known to be wrong. A person can scarcely know that the external action is morally wrong and be ignorant of the malice of an effective desire to commit such an action.

Again, the first principles of morality, which are certain general axioms of conduct, such as, Do to others as you would be done by, can scarcely fail to be known by anyone who has the use of reason. Even the secondary principles of the moral law, or the precepts of the Decalogue, are usually known by those who have attained the use of reason among civilized men; if in any case there is ignorance of them, it is vincible ignorance, and so more or less culpable. Theologians readily admit the possibility of an invincibly erroneous conscience concerning the application of the general principles of morality to concrete cases. The theological disputes which they chronicle are proof of the fact. 1 St Thomas, 1-2, q. 94, aa. 4, 6.

¹ St Thomas, 1-2, q. 19, a. 5.

² De Verit., q. 17, a. 5.