Summa Theologiae Moralis, vol. I: De Principiis

S. Th. I-II, q. 21, a. 1 and 2; q. 71, a. 1-4; de Malo, q. 2, a. 2.

413. Sin properly so called is taken philosophically and theologically:

a) Among philosophers an evil act is called sin, which is midway between evil and fault: for not every evil is a sin, nor is every sin a fault. Evil indeed is the privation of a perfection which ought to be present in something. But sin is the privation of a perfection due in order to the end, i.e. in operation when this is not so directed as its end requires; since however law is the rule according to which an act is to be directed so as to reach its end, it is the same whether sin be called: a disordering from the end, or: a transgression of law. Now there are three laws: the law of physical nature, the rules of an art, and moral law; hence a monster is said to be a sin of nature, and a faulty structure a sin of art. But the transgression of moral law has this special feature, that it arises from a free will, as being mistress of its own acts; and accordingly it is imputable and blameworthy: hence it has obtained the special name of fault.

b) But among theologians, who consider sin only in the moral realm and in relation to the last end, God, the custom of taking sin and fault in the same sense has prevailed. In the stricter sense, therefore, sin is a morally evil act, or an evil human act. And in this sense, in the present treatise, sin will be spoken of.

414. Sin is distinguished from vice and from malice in strict speech; although in common speech these are often confused: vice is a habitual inclination to sin or an evil habit, — sin, an evil act, — malice is the incongruity with right reason and law, on account of which an act or habit is evil and therefore a sin or a vice. Vice is directly opposed to virtue, sin to a good act, malice to goodness.

Sin has greater malice than vice, for 1) habit is midway between potency and act, and therefore just as it exceeds potency in good or evil because it inclines it to this, so it exceeds the act which determines the potency to this; whence it is worse to act evilly than merely to be able or to be inclined to it; 2) vice is not evil except because of the malice of the act, because it inclines to an evil act. — In a certain respect, however, vice is worse than sin, because it lasts longer and can be the efficient cause of many sins; but sin with respect to vice is the final cause according to which goodness or malice is considered, and therefore it is simply worse.

415. Sin differs from imperfection, which is either negative or physical, namely a defect of a greater perfection which an act could have, and this is proper to every created act; or positive or moral. This in turn is distinguished as twofold: one improperly so called is the transgression of a law of lesser moment entirely indeliberate, e.g. an entirely involuntary distraction in prayer: this is materially a true venial sin but without any fault; the other properly so called is a voluntary action or omission against a counsel to which one is stirred either by divine inspiration, or by the judgment of reason, or by the will of a superior directly, e.g. to omit morning prayers, to violate the statutes of a community, etc., and in this sense they are already accustomed to speak of imperfection. This in itself is not a sin because it is not against the law; nevertheless if it be done deliberately and especially habitually, it will not always be without fault, either by reason of an effect such as scandal or harm, or more often by reason of its cause, namely an inordinate affection or a perverse motive on account of which it is placed: whether from negligence or levity, or from inordinate passion such as sensuality, curiosity, concupiscence or anger, impatience, sloth, worldly fear, etc., or from contempt: for reason forbids that a man act from an evil or irrational motive in his acts.

Herein one must in fact altogether observe the essential difference between a precept, which of itself is obligatory, because it concerns a necessary good to be done or an evil to be avoided, and a counsel, which is not obligatory of itself, as being about a better good; so that any theory which would remove this difference in practice would thereby be shown to fall short of the truth. Wherefore the doctrine of those more recent authors cannot be admitted, who hold the omission of a better good to be of itself and necessarily and always culpable, unless it be proved from determined circumstances that in the case that good is less fitting or less good: these practitioners remove the difference of precept and counsel in practice. For the rest, they do not validly prove their assertion, although the burden of proof lies on the one who affirms. Precisely because we are dealing with a better good, which of itself pleases God more, there is also present a lesser good, which also of itself pleases God, as being good, although it pleases less because it is less good.

The omission, therefore, of the better and the choice of the lesser good is not of itself, necessarily and always irrational, nor accordingly evil: for it can be done from a reasonable motive, provided one does not positively intend to abandon the greater good, but chooses the lesser good because here and now it is fitting for him, from which the omission of the greater good indirectly follows. Therefore imperfection is not always a fault, but is not always without fault. And therefore it would be better called a less perfect act than an imperfection.

416. Conditions of sin. — Sin strictly so called is a voluntary act deprived of due order to the last end or of due rectitude; therefore two concur for it: a) inordination, from which it has the character of evil, namely the privation of due order to the last end and therefore a withdrawal from right reason and the law of God: this comes to it from the part of the object; b) the character of voluntary, from which it has the character of fault: this comes to it from the part of the act or subject. Hence three conditions are required for sin:

1. moral malice of the object, otherwise it would not be evil; but subjective malice in the object suffices, i.e. in the thing or action as known, and objective malice in the thing or action as it is in itself is not necessarily required: for he who thinks something is evil and does it, in fact wills evil, whence he who falsely believes it to be Friday and eats meat, nevertheless sins;

2. there is required in the subject some advertence to the malice¹

at least confused: for nothing is willed unless foreknown; whence if the evil is adverted to in no way, neither by suspecting it nor by doubting about it, man cannot will it; hence he does not sin who, on Friday, thinking nothing of the precept, eats meat;

3. there is required the consent of the will² direct or indirect, because sin is a human act; hence an act which is neither in the will nor from the will nor accepted by it is not a sin, as a temptation not accepted by the will is; — and indeed consent must be free³, whence the most vehement movements of anger or of another passion by which the use of reason and freedom are taken away excuse from sin.

If advertence to malice is lacking, the evil act which is placed is called material sin, which is an involuntary transgression of law; it is not sin because in the acting subject the voluntary is lacking, yet it is called sin because on the part of the object or matter about which all things required for sin are present. Formal sin, on the other hand, is the deliberate, voluntary, and culpable transgression of law, whether the law exists or is reputed to exist.

417. The notion of sin is not univocal but analogous⁴. — It is not univocal, which is predicated of all in the same manner under some genus, but it is called analogous whose property it is that according to the full and perfect notion it is predicated of one genus, namely of actual mortal sin, imperfectly, deficiently, and in a qualified sense of others: for the essential elements which are found in every sin, namely the ratio of a voluntary act and inordination, are diverse. For:

1. Sin primarily and originally is an act, but secondarily and consequently it is also so called properly and is the inordination which follows the act, or the state of sin, which is not an evil act except in a qualified sense, insofar as the act morally or by guilt persists.

2. Mortal and venial sin differ in the notion of inordination: the former is perfectly against the law from whose end it turns the soul through charity; the latter only imperfectly, and therefore it only retards from the end.

3. Personal and original sin differ in the notion of voluntary: the former is voluntary by one's own will, the latter is most imperfectly voluntary, namely not by one's own will but only by the will of our head Adam.

418. Sin is called in Scripture: 1) in relation to the end: ἁμαρτία and ἀμάρτημα i.e. a wandering from the end (Rom. V, 12; VII, 7), so however that the first word is said also of the state of sin, the second of the act alone; — 2) in relation to the law of God: ἀνομία and παράνομια (in Vulg. iniquity) i.e. violation or contempt of law (I John III, 4; II Pet. II, 15); παράβασις i.e. transgression or prevarication of law (Rom. V, 14; Gal. III, 19; I Tim. II, 14); παράκοή i.e. the will not to hear the voice of God or disobedience (Rom. V, 19; Heb. II, 2); — 3) in relation to the sinner: παράπτωμα i.e. a fall (Mk. XI, 25-26); ἥττημα i.e. a disaster, a diminution (Rom. XI, 12); ἀγνόημα i.e. ignorance, because every sin involves a culpable error (Heb. XI, 7; Acts XVII, 30).

More often also sin is taken in a metaphorical and improper sense, either for a sacrifice offered for sins (Hos. IV, 8; II Cor. V, 21), or for a cause, occasion, or object of sin (Deut. IX, 21), or even for its punishment or effect (Lev. XX, 20), or for cause and effect together, as concupiscence is called sin by the Apostle (Rom. VII, 17) because it is from sin and inclines to sin (C. Trid. sess. 5, can. 5).