Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that every human action is good, and that none is evil. For Dionysius says (Div. Nom. iv) that evil acts not, save in virtue of the good. But no evil is done in virtue of the good. Therefore no action is evil.

Objection 2: Further, nothing acts except in so far as it is in act. Now a thing is evil, not according as it is in act, but according as its potentiality is void of act; whereas in so far as its potentiality is perfected by act, it is good, as stated in Metaph. ix, 9. Therefore nothing acts in so far as it is evil, but only according as it is good. Therefore every action is good, and none is evil.

Objection 3: Further, evil cannot be a cause, save accidentally, as Dionysius declares (Div. Nom. iv). But every action has some effect which is proper to it. Therefore no action is evil, but every action is good.

On the contrary, Our Lord said (Jn. 3:20): "Every one that doth evil, hateth the light." Therefore some actions of man are evil.

I answer that, We must speak of good and evil in actions as of good and evil in things: because such as everything is, such is the act that it produces. Now in things, each one has so much good as it has being: since good and being are convertible, as was stated in the 1, Question 5, Articles 1,3. But God alone has the whole plenitude of His Being in a certain unity: whereas every other thing has its proper fulness of being in a certain multiplicity. Wherefore it happens with some things, that they have being in some respect, and yet they are lacking in the fulness of being due to them. Thus the fulness of human being requires a compound of soul and body, having all the powers and instruments of knowledge and movement: wherefore if any man be lacking in any of these, he is lacking in something due to the fulness of his being. So that as much as he has of being, so much has he of goodness: while so far as he is lacking in goodness, and is said to be evil: thus a blind man is possessed of goodness inasmuch as he lives; and of evil, inasmuch as he lacks sight. That, however, which has nothing of being or goodness, could not be said to be either evil or good. But since this same fulness of being is of the very essence of good, if a thing be lacking in its due fulness of being, it is not said to be good simply, but in a certain respect, inasmuch as it is a being; although it can be called a being simply, and a non-being in a certain respect, as was stated in the 1, Question 5, Article 1, ad 1. We must therefore say that every action has goodness, in so far as it has being; whereas it is lacking in goodness, in so far as it is lacking in something that is due to its fulness of being; and thus it is said to be evil: for instance if it lacks the quantity determined by reason, or its due place, or something of the kind.

Reply to Objection 1: Evil acts in virtue of deficient goodness. For it there were nothing of good there, there would be neither being nor possibility of action. On the other hand if good were not deficient, there would be no evil. Consequently the action done is a deficient good, which is good in a certain respect, but simply evil.

Reply to Objection 2: Nothing hinders a thing from being in act in a certain respect, so that it can act; and in a certain respect deficient in act, so as to cause a deficient act. Thus a blind man has in act the power of walking, whereby he is able to walk; but inasmuch as he is deprived of sight he suffers a defect in walking by stumbling when he walks.

Reply to Objection 3: An evil action can have a proper effect, according to the goodness and being that it has. Thus adultery is the cause of human generation, inasmuch as it implies union of male and female, but not inasmuch as it lacks the order of reason.

Articulus 1

Argumentum 1

Ad primum sic proceditur. Videtur quod omnis actio hominis sit bona, et nulla sit mala.

Dicit enim dionysius, IV cap. De div. Nom., quod malum non agit nisi virtute boni.

Sed virtute boni non fit malum. Ergo nulla actio est mala.

Argumentum 2

Praeterea, nihil agit nisi secundum quod est actu. Non est autem aliquid malum secundum quod est actu, sed secundum quod potentia privatur actu, inquantum autem potentia perficitur per actum, est bonum, ut dicitur in IX metaphys..

Nihil ergo agit inquantum est malum, sed solum inquantum est bonum.

Omnis ergo actio est bona, et nulla mala.

Argumentum 3

Praeterea, malum non potest esse causa nisi per accidens, ut patet per dionysium, IV cap. De div. Nom..

Sed omnis actionis est aliquis per se effectus.

Nulla ergo actio est mala, sed omnis actio est bona.

Sed Contra

Sed contra est quod dominus dicit, Ioan. III, omnis qui male agit, odit lucem.

Est ergo aliqua actio hominis mala.

Corpus

Respondeo dicendum quod de bono et malo in actionibus oportet loqui sicut de bono et malo in rebus, eo quod unaquaeque res talem actionem producit, qualis est ipsa. In rebus autem unumquodque tantum habet de bono, quantum habet de esse, bonum enim et ens convertuntur, ut in primo dictum est.

Solus autem deus habet totam plenitudinem sui esse secundum aliquid unum et simplex, unaquaeque vero res alia habet plenitudinem essendi sibi convenientem secundum diversa.

Unde in aliquibus contingit quod quantum ad aliquid habent esse, et tamen eis aliquid deficit ad plenitudinem essendi eis debitam.

Sicut ad plenitudinem esse humani requiritur quod sit quoddam compositum ex anima et corpore, habens omnes potentias et instrumenta cognitionis et motus, unde si aliquid horum deficiat alicui homini deficit ei aliquid de plenitudine sui esse.

Quantum igitur habet de esse, tantum habet de bonitate, inquantum vero aliquid ei deficit de plenitudine essendi, intantum deficit a bonitate, et dicitur malum, sicut homo caecus habet de bonitate quod vivit, et malum est ei quod caret visu.

Si vero nihil haberet de entitate vel bonitate, neque malum neque bonum dici posset. Sed quia de ratione boni est ipsa plenitudo essendi, si quidem alicui aliquid defuerit de debita essendi plenitudine, non dicetur simpliciter bonum, sed secundum quid, inquantum est ens, poterit tamen dici simpliciter ens et secundum quid non ens, ut in primo dictum est.

Sic igitur dicendum est quod omnis actio, inquantum habet aliquid de esse, intantum habet de bonitate, inquantum vero deficit ei aliquid de plenitudine essendi quae debetur actioni humanae, intantum deficit a bonitate, et sic dicitur mala, puta si deficiat ei vel determinata quantitas secundum rationem, vel debitus locus, vel aliquid huiusmodi.

Ad 1

Ad primum ergo dicendum quod malum agit in virtute boni deficientis. Si enim nihil esset ibi de bono, neque esset ens, neque agere posset. Si autem non esset deficiens, non esset malum.

Unde et actio causata est quoddam bonum deficiens, quod secundum quid est bonum, simpliciter autem malum.

Ad 2

Ad secundum dicendum quod nihil prohibet aliquid esse secundum quid in actu, unde agere possit; et secundum aliud privari actu, unde causet deficientem actionem. Sicut homo caecus actu habet virtutem gressivam, per quam ambulare potest, sed inquantum caret visu, qui dirigit in ambulando, patitur defectum in ambulando, dum ambulat cespitando.

Ad 3

Ad tertium dicendum quod actio mala potest habere aliquem effectum per se, secundum id quod habet de bonitate et entitate.

Sicut adulterium est causa generationis humanae, inquantum habet commixtionem maris et feminae, non autem inquantum caret ordine rationis.