Summa Theologiae Moralis, vol. I: De Principiis

S. Th. I-II, q. 72; de Malo, q. 2, a. 6.

432. Principle I. Sins are specifically distinguished immediately and proximately according to diverse formal objects, or a morally distinct species. For sin is not a simple privation but a voluntary act deprived of due rectitude, whence just as other human acts, sins will have their species immediately from the object: thus idolatry, homicide, and gluttony are distinguished (a. 1). — Since however the end or good is the proper object of the will, it follows that sins are specifically distinguished according to diverse ends (ad 1), whether of the agent (as e.g. to steal out of vengeance or out of fornication), or especially intrinsic to the work itself (as e.g. gluttony for pleasure, theft for money; — gluttony from love of delicious food or from love of much food).

433. Principle II. Sins are not specifically distinguished immediately and proximately, as opposed to the diverse virtues from which they withdraw (as Scotus taught) or to the diverse precepts (as Vasquez said): for the privation which is had in sin, namely a withdrawal from virtue or law, is not intended by the sinner but is beside his intention, whence it is not of itself and directly the object of the will and human act, nor therefore gives the evil act its species (a. 1).

S. Thomas noted that it comes to the same thing, that sins are distinguished in species either according to objects or according to the virtues to which they are opposed, because the virtues themselves are distinguished in species by their objects (ad 2); — or also according to precepts, because these differ according to a diverse object, motive, and end, and also according to diverse virtues, since they are given for this, that we may work according to virtue. Sins, therefore, although they do not immediately take their species from the law which they transgress, or from the virtue from which they withdraw, yet remotely and mediately they can be said to receive their species from them¹.

434. Practical rules are usually laid down as follows, by which the specific distinction of objects and accordingly of sins is easily discerned:

1st, altogether universal, to which all others can be reduced: Sins are diverse which are concerned with formally diverse objects; but objects are formally diverse not according to physical being but according to moral being, i.e. according to a special agreement or repugnance with right reason and the eternal law: hence to steal a sheep or a horse or money is the same sin in species, although the objects are materially diverse, because they agree in one moral notion, in taking another's good; — on the contrary homicide, adultery, and theft, because they contain a diverse repugnance to reason, since they injure a different right to life, to wife, to external goods (a. 1 and ad 3).

2nd: Those sins are diverse which are opposed to diverse virtues: for each virtue has its own proper goodness. Hence theft, fornication, and perjury are distinguished because they are opposed to justice, chastity, and religion (ad 2).

3rd: Those sins are diverse which are opposed to the same virtue but in a contrary way, that is by excess and defect, as presumption and despair of hope, prodigality and avarice to the virtue of liberality: for they are placed from an opposite motive and withdraw from the virtue in a diverse notion (a. 8).

4th: Those sins are diverse which are opposed to the same virtue, not in a contrary way but in a diverse way, on account of a special repugnance with right reason and law; in other words, which are against diverse goods, rectitudes, honesties, offices of the same virtue, as e.g. homicide and theft, theft and robbery, contumely and detraction, real, personal, and local sacrilege, violation of vow and of oath, idolatry and magic, perjury and blasphemy: for then a diverse goodness is injured and in the objects there is a deformity of a distinct notion is had.

5th: Those sins are diverse which are repugnant to formally diverse precepts, i.e. given for a diverse motive or intrinsic end, but not those which are repugnant to many precepts given for the same intrinsic motive, even if they are given by diverse legislators. Hence one who is bound by vow and by the precept of the confessor to fast on Ember Friday, if he does not fast, commits a threefold sin specifically distinct against temperance, religion, and the virtue of penance; — on the contrary, he who omits the holy day falling on a Sunday, or does not fast on Ember Saturday falling on a vigil, because each precept is of the same notion on the part of the end or intrinsic motive; likewise there is only one sin which is forbidden by natural, divine, ecclesiastical, and civil law, such as homicide.

435. Circumstances only per se aggravate sin. — For many pertain to the same object and the same matter, as e.g. from the same motive a prodigal gives when, where, to whom he ought not, and an illiberal man takes when, where it is not fitting, and more than is fitting. — They change species however if they include a special and distinct deformity with reason or proceed from a special motive; but then they do not remain circumstances but become as it were a secondary object of the act and have the character of a specific difference. Thus theft of a sacred thing is specifically distinguished from simple theft, likewise the various sins of gluttony such as eating too much or food that is too delicious (a. 9).

436. Corollaries. — A. Therefore sins are specifically distinguished: a) carnal and spiritual sins, because they tend to formally diverse objects: for carnal sins, namely gluttony and lust and what is reduced to them, have as their end carnal pleasure which is perfected in bodily touch, spiritual [sins have] spiritual pleasure which is consummated in the knowledge of something, as the other five capital [sins] (a. 2).

b) Likewise sins against God, against oneself, and against neighbor, for the objects and virtues by which man is ordered to God, to neighbor, and to oneself are specifically diverse. It is to be noted that every sin which is against neighbor and against oneself is also against God: but here under the name of sin against God comes that which is proximately, immediately, and specially against him, without being against neighbor and oneself (a. 4).

B. Sins are not specifically distinguished: a) because they differ according to liability to punishment, namely mortal and venial. For the will of the sinner does not intend the punishment of sin, but this is accidental and beside his intention. Since therefore the liability to punishment is not the object of the sinful act but follows accidentally, it does not cause a difference of species.

Mortal and venial sin differ infinitely on the part of inordination or privation, not however on the part of conversion to a created good, on the part of the act and object, from which nevertheless they have their species. Nothing therefore prevents mortal and venial sin being found in the same moral species, just as the first movement in the genus of adultery, or theft of 10 cents, is venial (a. 5).

Likewise b) because they are sins of heart, mouth, and work: although indeed per accidens they differ in completed species if they are consummated and perfect either in thought, or in word, or in work, such as heresy, blasphemy, and idolatry, because then they have diverse ends or objects; per se however they indicate only degrees of one species of sin, whose 1st beginning is in the affection of the heart, 2nd degree in the manifestation of the mouth, 3rd in the consummation of the work, as e.g. the desire, proposal, and perpetration of adultery; to conceive in the heart anger toward another, to express it in harsh words, and to strike him (a. 7).

Hence 1) they are not distinguished when they are joined together; 2) but if one or another degree is found separately and the will does not proceed further and does not carry out the sin, then they are distinguished in incomplete species, because then they are related as incomplete and complete species in the same way as a part of a movement and the whole movement, an imperfect work and a complete one, as e.g. the laying of a foundation and the building of a house. Thus internal lust, imperfect lust of the mouth, sight, or touch, and consummate or perfect lust of deed (ad 3).

Likewise c) because they are sins of commission and omission: although indeed according to physical being they are distinguished in species and even in genus, according to moral being they are not necessarily distinguished in species, because they can be concerned with the same object, tend to the same end, and proceed from the same motive, such as to rob another's goods and not to restore them, to watch and to sleep against the precept of a superior, to omit Mass or to steal for adultery, etc. (a. 6).