Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that sin is unfittingly defined by saying: "Sin is a word, deed, or desire, contrary to the eternal law." Because "Word," "deed," and "desire" imply an act; whereas not every sin implies an act, as stated above (Article 5). Therefore this definition does not include every sin.

Objection 2: Further, Augustine says (De Duab. Anim. xii): "Sin is the will to retain or obtain what justice forbids." Now will is comprised under desire, in so far as desire denotes any act of the appetite. Therefore it was enough to say: "Sin is a desire contrary to the eternal law," nor was there need to add "word" or "deed."

Objection 3: Further, sin apparently consists properly in aversion from the end: because good and evil are measured chiefly with regard to the end as explained above (Question 1, Article 3; Question 18, Articles 4,6; Question 20, Articles 2,3): wherefore Augustine (De Lib. Arb. i) defines sin in reference to the end, by saying that "sin is nothing else than to neglect eternal things, and seek after temporal things": and again he says (Qq. lxxxii, qu. 30) that "all human wickedness consists in using what we should enjoy, and in enjoying what we should use." Now the definition is question contains no mention of aversion from our due end: therefore it is an insufficient definition of sin.

Objection 4: Further, a thing is said to be forbidden, because it is contrary to the law. Now not all sins are evil through being forbidden, but some are forbidden because they are evil. Therefore sin in general should not be defined as being against the law of God.

Objection 5: Further, a sin denotes a bad human act, as was explained above (Article 1). Now man's evil is to be against reason, as Dionysius states (Div. Nom. iv). Therefore it would have been better to say that sin is against reason than to say that it is contrary to the eternal law.

On the contrary, the authority of Augustine suffices (Contra Faust. xxii, 27).

I answer that, As was shown above (Article 1), sin is nothing else than a bad human act. Now that an act is a human act is due to its being voluntary, as stated above (Question 1, Article 1), whether it be voluntary, as being elicited by the will, e.g. to will or to choose, or as being commanded by the will, e.g. the exterior actions of speech or operation. Again, a human act is evil through lacking conformity with its due measure: and conformity of measure in a thing depends on a rule, from which if that thing depart, it is incommensurate. Now there are two rules of the human will: one is proximate and homogeneous, viz. the human reason; the other is the first rule, viz. the eternal law, which is God's reason, so to speak. Accordingly Augustine (Contra Faust. xxii, 27) includes two things in the definition of sin; one, pertaining to the substance of a human act, and which is the matter, so to speak, of sin, when he says "word," "deed," or "desire"; the other, pertaining to the nature of evil, and which is the form, as it were, of sin, when he says, "contrary to the eternal law."

Reply to Objection 1: Affirmation and negation are reduced to one same genus: e.g. in Divine things, begotten and unbegotten are reduced to the genus "relation," as Augustine states (De Trin. v, 6,7): and so "word" and "deed" denote equally what is said and what is not said, what is done and what is not done.

Reply to Objection 2: The first cause of sin is in the will, which commands all voluntary acts, in which alone is sin to be found: and hence it is that Augustine sometimes defines sin in reference to the will alone. But since external acts also pertain to the substance of sin, through being evil of themselves, as stated, it was necessary in defining sin to include something referring to external action.

Reply to Objection 3: The eternal law first and foremost directs man to his end, and in consequence, makes man to be well disposed in regard to things which are directed to the end: hence when he says, "contrary to the eternal law," he includes aversion from the end and all other forms of inordinateness.

Reply to Objection 4: When it is said that not every sin is evil through being forbidden, this must be understood of prohibition by positive law. If, however, the prohibition be referred to the natural law, which is contained primarily in the eternal law, but secondarily in the natural code of the human reason, then every sin is evil through being prohibited: since it is contrary to natural law, precisely because it is inordinate.

Reply to Objection 5: The theologian considers sin chiefly as an offense against God; and the moral philosopher, as something contrary to reason. Hence Augustine defines sin with reference to its being "contrary to the eternal law," more fittingly than with reference to its being contrary to reason; the more so, as the eternal law directs us in many things that surpass human reason, e.g. in matters of faith.

Articulus 6

Argumentum 1

Ad sextum sic proceditur. Videtur quod inconvenienter definiatur peccatum, cum dicitur, peccatum est dictum vel factum vel concupitum contra legem aeternam.

Dictum enim, vel factum, vel concupitum, importat aliquem actum.

Sed non omne peccatum importat aliquem actum, ut dictum est.

Ergo haec definitio non includit omne peccatum.

Argumentum 2

Praeterea, Augustinus dicit, in libro de duabus animabus, peccatum est voluntas retinendi vel consequendi quod iustitia vetat.

Sed voluntas sub concupiscentia comprehenditur, secundum quod concupiscentia largo modo sumitur, pro omni appetitu.

Ergo suffecisset dicere, peccatum est concupitum contra legem aeternam; nec oportuit addere, dictum vel factum.

Argumentum 3

Praeterea, peccatum proprie consistere videtur in aversione a fine, nam bonum et malum principaliter considerantur secundum finem, ut ex supradictis patet.

Unde et Augustinus, in I de Lib. Arb., per comparationem ad finem definit peccatum, dicens quod peccare nihil est aliud quam, neglectis rebus aeternis, temporalia sectari, et in libro octoginta trium quaest., dicit quod omnis humana perversitas est uti fruendis et frui utendis.

Sed in praemissa definitione nulla fit mentio de aversione a debito fine. Ergo insufficienter definitur peccatum.

Argumentum 4

Praeterea, ex hoc dicitur aliquid esse prohibitum, quia legi contrariatur. Sed non omnia peccata sunt mala quia prohibita, sed quaedam sunt prohibita quia mala. Non ergo in communi definitione peccati debuit poni quod sit contra legem dei.

Argumentum 5

Praeterea, peccatum significat malum hominis actum, ut ex dictis patet.

Sed malum hominis est contra rationem esse, ut dionysius dicit, IV cap. De div. Nom..

Ergo potius debuit dici quod peccatum sit contra rationem, quam quod peccatum sit contra legem aeternam.

Sed Contra

In contrarium sufficit auctoritas Augustini.

Corpus

Respondeo dicendum quod, sicut ex dictis patet, peccatum nihil aliud est quam actus humanus malus.

Quod autem aliquis actus sit humanus, habet ex hoc quod est voluntarius, sicut ex supradictis patet, sive sit voluntarius quasi a voluntate elicitus, ut ipsum velle et eligere; sive quasi a voluntate imperatus, ut exteriores actus vel locutionis vel operationis. Habet autem actus humanus quod sit malus, ex eo quod caret debita commensuratione. Omnis autem commensuratio cuiuscumque rei attenditur per comparationem ad aliquam regulam, a qua si divertat, incommensurata erit. Regula autem voluntatis humanae est duplex, una propinqua et homogenea, scilicet ipsa humana ratio; alia vero est prima regula, scilicet lex aeterna, quae est quasi ratio dei. Et ideo Augustinus in definitione peccati posuit duo, unum quod pertinet ad substantiam actus humani, quod est quasi materiale in peccato, cum dixit, dictum vel factum vel concupitum; aliud autem quod pertinet ad rationem mali, quod est quasi formale in peccato, cum dixit, contra legem aeternam.

Ad 1

Ad primum ergo dicendum quod affirmatio et negatio reducuntur ad idem genus, sicut in divinis genitum et ingenitum ad relationem, ut Augustinus dicit, in V de Trin..

Et ideo pro eodem est accipiendum dictum et non dictum, factum et non factum.

Ad 2

Ad secundum dicendum quod prima causa peccati est in voluntate, quae imperat omnes actus voluntarios, in quibus solum invenitur peccatum, et ideo Augustinus quandoque per solam voluntatem definit peccatum.

Sed quia etiam ipsi exteriores actus pertinent ad substantiam peccati, cum sint secundum se mali, ut dictum est, necesse fuit quod in definitione peccati poneretur etiam aliquid pertinens ad exteriores actus.

Ad 3

Ad tertium dicendum quod lex aeterna primo et principaliter ordinat hominem ad finem, consequenter autem facit hominem bene se habere circa ea quae sunt ad finem. Et ideo in hoc quod dicit contra legem aeternam, tangit aversionem a fine, et omnes alias inordinationes.

Ad 4

Ad quartum dicendum quod, cum dicitur quod non omne peccatum ideo est malum quia est prohibitum, intelligitur de prohibitione facta per ius positivum. Si autem referatur ad ius naturale, quod continetur primo quidem in lege aeterna, secundario vero in naturali iudicatorio rationis humanae, tunc omne peccatum est malum quia prohibitum, ex hoc enim ipso quod est inordinatum, iuri naturali repugnat.

Ad 5

Ad quintum dicendum quod a theologis consideratur peccatum praecipue secundum quod est offensa contra deum, a philosopho autem morali, secundum quod contrariatur rationi.

Et ideo Augustinus convenientius definit peccatum ex hoc quod est contra legem aeternam, quam ex hoc quod est contra rationem, praecipue cum per legem aeternam regulemur in multis quae excedunt rationem humanam, sicut in his quae sunt fidei.