Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that the division of sins according to their debt of punishment diversifies their species; for instance, when sin is divided into "mortal" and "venial." For things which are infinitely apart, cannot belong to the same species, nor even to the same genus. But venial and mortal sin are infinitely apart, since temporal punishment is due to venial sin, and eternal punishment to mortal sin; and the measure of the punishment corresponds to the gravity of the fault, according to Dt. 25:2: "According to the measure of the sin shall the measure be also of the stripes be." Therefore venial and mortal sins are not of the same genus, nor can they be said to belong to the same species.

Objection 2: Further, some sins are mortal in virtue of their species , as murder and adultery; and some are venial in virtue of their species, as in an idle word, and excessive laughter. Therefore venial and mortal sins differ specifically.

Objection 3: Further, just as a virtuous act stands in relation to its reward, so does sin stand in relation to punishment. But the reward is the end of the virtuous act. Therefore punishment is the end of sin. Now sins differ specifically in relation to their ends, as stated above (Article 1, ad 1). Therefore they are also specifically distinct according to the debt of punishment.

On the contrary, Those things that constitute a species are prior to the species, e.g. specific differences. But punishment follows sin as the effect thereof. Therefore sins do not differ specifically according to the debt of punishment.

I answer that, In things that differ specifically we find a twofold difference: the first causes the diversity of species, and is not to be found save in different species, e.g. "rational" and "irrational," "animate," and "inanimate": the other difference is consequent to specific diversity; and though, in some cases, it may be consequent to specific diversity, yet, in others, it may be found within the same species; thus "white" and "black" are consequent to the specific diversity of crow and swan, and yet this difference is found within the one species of man.

We must therefore say that the difference between venial and mortal sin, or any other difference is respect of the debt of punishment, cannot be a difference constituting specific diversity. For what is accidental never constitutes a species; and what is outside the agent's intention is accidental (Phys. ii, text. 50). Now it is evident that punishment is outside the intention of the sinner, wherefore it is accidentally referred to sin on the part of the sinner. Nevertheless it is referred to sin by an extrinsic principle, viz. the justice of the judge, who imposes various punishments according to the various manners of sin. Therefore the difference derived from the debt of punishment, may be consequent to the specific diversity of sins, but cannot constitute it.

Now the difference between venial and mortal sin is consequent to the diversity of that inordinateness which constitutes the notion of sin. For inordinateness is twofold, one that destroys the principle of order, and another which, without destroying the principle of order, implies inordinateness in the things which follow the principle: thus, in an animal's body, the frame may be so out of order that the vital principle is destroyed; this is the inordinateness of death; while, on the other hand, saving the vital principle, there may be disorder in the bodily humors; and then there is sickness. Now the principle of the entire moral order is the last end, which stands in the same relation to matters of action, as the indemonstrable principle does to matters of speculation (Ethic. vii, 8). Therefore when the soul is so disordered by sin as to turn away from its last end, viz. God, to Whom it is united by charity, there is mortal sin; but when it is disordered without turning away from God, there is venial sin. For even as in the body, the disorder of death which results from the destruction of the principle of life, is irreparable according to nature, while the disorder of sickness can be repaired by reason of the vital principle being preserved, so it is in matters concerning the soul. Because, in speculative matters, it is impossible to convince one who errs in the principles, whereas one who errs, but retains the principles, can be brought back to the truth by means of the principles. Likewise in practical matters, he who, by sinning, turns away from his last end, if we consider the nature of his sin, falls irreparably, and therefore is said to sin mortally and to deserve eternal punishment: whereas when a man sins without turning away from God, by the very nature of his sin, his disorder can be repaired, because the principle of the order is not destroyed; wherefore he is said to sin venially, because, to wit, he does not sin so as to deserve to be punished eternally.

Reply to Objection 1: Mortal and venial sins are infinitely apart as regards what they "turn away from," not as regards what they "turn to," viz. the object which specifies them. Hence nothing hinders the same species from including mortal and venial sins; for instance, in the species "adultery" the first movement is a venial sin; while an idle word, which is, generally speaking, venial, may even be a mortal sin.

Reply to Objection 2: From the fact that one sin is mortal by reason of its species, and another venial by reason of its species, it follows that this difference is consequent to the specific difference of sins, not that it is the cause thereof. And this difference may be found even in things of the same species, as stated above.

Reply to Objection 3: The reward is intended by him that merits or acts virtually; whereas the punishment is not intended by the sinner, but, on the contrary, is against his will. Hence the comparison fails.

Articulus 5

Argumentum 1

Ad quintum sic proceditur. Videtur quod divisio peccatorum quae est secundum reatum, diversificet speciem, puta cum dividitur secundum veniale et mortale.

Ea enim quae in infinitum differunt, non possunt esse unius speciei, nec etiam unius generis. Sed veniale et mortale peccatum differunt in infinitum, veniali enim debetur poena temporalis, mortali poena aeterna; mensura autem poenae respondet quantitati culpae, secundum illud Deut. XXV, pro mensura delicti erit et plagarum modus.

Ergo veniale et mortale non sunt unius generis, nedum quod sint unius speciei.

Argumentum 2

Praeterea, quaedam peccata sunt mortalia ex genere, sicut homicidium et adulterium, quaedam vero ex suo genere sunt peccata venialia, sicut verbum otiosum et risus superfluus.

Ergo peccatum veniale et mortale specie differunt.

Argumentum 3

Praeterea, sicut se habet actus virtuosus ad praemium, ita se habet peccatum ad poenam. Sed praemium est finis virtuosi actus. Ergo et poena est finis peccati.

Sed peccata distinguuntur specie secundum fines, ut dictum est.

Ergo etiam distinguuntur specie secundum reatum poenae.

Sed Contra

Sed contra, ea quae constituunt speciem, sunt priora, sicut differentiae specificae. Sed poena sequitur culpam, sicut effectus eius. Ergo peccata non differunt specie secundum reatum poenae.

Corpus

Respondeo dicendum quod eorum quae specie differunt, duplex differentia invenitur. Una quidem quae constituit diversitatem specierum, et talis differentia nunquam invenitur nisi in speciebus diversis; sicut rationale et irrationale, animatum et inanimatum. Alia autem differentia est consequens diversitatem speciei, et talis differentia, etsi in aliquibus consequatur diversitatem speciei, in aliis tamen potest inveniri in eadem specie; sicut album et nigrum consequuntur diversitatem speciei corvi et cygni, tamen invenitur huiusmodi differentia in eadem hominis specie.

Dicendum est ergo quod differentia venialis et mortalis peccati, vel quaecumque alia differentia sumitur penes reatum, non potest esse differentia constituens diversitatem speciei.

Nunquam enim id quod est per accidens, constituit speciem.

Id autem quod est praeter intentionem agentis, est per accidens, ut patet in II physic..

Manifestum est autem quod poena est praeter intentionem peccantis. Unde per accidens se habet ad peccatum, ex parte ipsius peccantis.

Ordinatur tamen ad peccatum ab exteriori, scilicet ex iustitia iudicantis, qui secundum diversas conditiones peccatorum diversas poenas infligit. Unde differentia quae est ex reatu poenae, potest consequi diversam speciem peccatorum; non autem constituit diversitatem speciei.

Differentia autem peccati venialis et mortalis consequitur diversitatem inordinationis, quae complet rationem peccati.

Duplex enim est inordinatio, una per subtractionem principii ordinis; alia qua, salvato principio ordinis, fit inordinatio circa ea quae sunt post principium. Sicut in corpore animalis quandoque quidem inordinatio complexionis procedit usque ad destructionem principii vitalis, et haec est mors, quandoque vero, salvo principio vitae, fit inordinatio quaedam in humoribus, et tunc est aegritudo. Principium autem totius ordinis in moralibus est finis ultimus, qui ita se habet in operativis, sicut principium indemonstrabile in speculativis, ut dicitur in VII ethic..

Unde quando anima deordinatur per peccatum usque ad aversionem ab ultimo fine, scilicet deo, cui unimur per caritatem, tunc est peccatum mortale, quando vero fit deordinatio citra aversionem a deo, tunc est peccatum veniale. Sicut enim in corporalibus deordinatio mortis, quae est per remotionem principii vitae, est irreparabilis secundum naturam; inordinatio autem aegritudinis reparari potest, propter id quod salvatur principium vitae; similiter est in his quae pertinent ad animam. Nam in speculativis qui errat circa principia, impersuasibilis est, qui autem errat salvatis principiis, per ipsa principia revocari potest. Et similiter in operativis qui peccando avertitur ab ultimo fine, quantum est ex natura peccati, habet lapsum irreparabilem, et ideo dicitur peccare mortaliter, aeternaliter puniendus. Qui vero peccat citra aversionem a deo, ex ipsa ratione peccati reparabiliter deordinatur, quia salvatur principium, et ideo dicitur peccare venialiter, quia scilicet non ita peccat ut mereatur interminabilem poenam.

Ad 1

Ad primum ergo dicendum quod peccatum mortale et veniale differunt in infinitum ex parte aversionis, non autem ex parte conversionis, per quam respicit obiectum, unde peccatum speciem habet. Unde nihil prohibet in eadem specie inveniri aliquod peccatum mortale et veniale, sicut primus motus in genere adulterii est peccatum veniale; et verbum otiosum, quod plerumque est veniale, potest etiam esse mortale.

Ad 2

Ad secundum dicendum quod ex hoc quod invenitur aliquod peccatum mortale ex genere, et aliquod peccatum veniale ex genere, sequitur quod talis differentia consequatur diversitatem peccatorum secundum speciem, non autem quod causet eam. Talis autem differentia potest inveniri etiam in his quae sunt eiusdem speciei, ut dictum est.

Ad 3

Ad tertium dicendum quod praemium est de intentione merentis vel virtuose agentis, sed poena non est de intentione peccantis, sed magis est contra voluntatem ipsius.

Unde non est similis ratio.