Thomas Aquinas, Summa Theologiae

Objection 1: It would seem that evil is a nature. For every genus is a nature. But evil is a genus; for the Philosopher says (Praedic. x) that "good and evil are not in a genus, but are genera of other things." Therefore evil is a nature.

Objection 2: Further, every difference which constitutes a species is a nature. But evil is a difference constituting a species of morality; for a bad habit differs in species from a good habit, as liberality from illiberality. Therefore evil signifies a nature.

Objection 3: Further, each extreme of two contraries is a nature. But evil and good are not opposed as privation and habit, but as contraries, as the Philosopher shows (Praedic. x) by the fact that between good and evil there is a medium, and from evil there can be a return to good. Therefore evil signifies a nature.

Objection 4: Further, what is not, acts not. But evil acts, for it corrupts good. Therefore evil is a being and a nature.

Objection 5: Further, nothing belongs to the perfection of the universe except what is a being and a nature. But evil belongs to the perfection of the universe of things; for Augustine says (Enchir. 10,11) that the "admirable beauty of the universe is made up of all things. In which even what is called evil, well ordered and in its place, is the eminent commendation of what is good." Therefore evil is a nature.

On the contrary, Dionysius says (Div. Nom. iv), "Evil is neither a being nor a good."

I answer that, One opposite is known through the other, as darkness is known through light. Hence also what evil is must be known from the nature of good. Now, we have said above that good is everything appetible; and thus, since every nature desires its own being and its own perfection, it must be said also that the being and the perfection of any nature is good. Hence it cannot be that evil signifies being, or any form or nature. Therefore it must be that by the name of evil is signified the absence of good. And this is what is meant by saying that "evil is neither a being nor a good." For since being, as such, is good, the absence of one implies the absence of the other.

Reply to Objection 1: Aristotle speaks there according to the opinion of Pythagoreans, who thought that evil was a kind of nature; and therefore they asserted the existence of the genus of good and evil. For Aristotle, especially in his logical works, brings forward examples that in his time were probable in the opinion of some philosophers. Or, it may be said that, as the Philosopher says (Metaph. iv, text 6), "the first kind of contrariety is habit and privation," as being verified in all contraries; since one contrary is always imperfect in relation to another, as black in relation to white, and bitter in relation to sweet. And in this way good and evil are said to be genera not simply, but in regard to contraries; because, as every form has the nature of good, so every privation, as such, has the nature of evil.

Reply to Objection 2: Good and evil are not constitutive differences except in morals, which receive their species from the end, which is the object of the will, the source of all morality. And because good has the nature of an end, therefore good and evil are specific differences in moral things; good in itself, but evil as the absence of the due end. Yet neither does the absence of the due end by itself constitute a moral species, except as it is joined to the undue end; just as we do not find the privation of the substantial form in natural things, unless it is joined to another form. Thus, therefore, the evil which is a constitutive difference in morals is a certain good joined to the privation of another good; as the end proposed by the intemperate man is not the privation of the good of reason, but the delight of sense without the order of reason. Hence evil is not a constitutive difference as such, but by reason of the good that is annexed.

Reply to Objection 3: This appears from the above. For the Philosopher speaks there of good and evil in morality. Because in that respect, between good and evil there is a medium, as good is considered as something rightly ordered, and evil as a thing not only out of right order, but also as injurious to another. Hence the Philosopher says (Ethic. iv, i) that a "prodigal man is foolish, but not evil." And from this evil in morality, there may be a return to good, but not from any sort of evil, for from blindness there is no return to sight, although blindness is an evil.

Reply to Objection 4: A thing is said to act in a threefold sense. In one way, formally, as when we say that whiteness makes white; and in that sense evil considered even as a privation is said to corrupt good, forasmuch as it is itself a corruption or privation of good. In another sense a thing is said to act effectively, as when a painter makes a wall white. Thirdly, it is said in the sense of the final cause, as the end is said to effect by moving the efficient cause. But in these two ways evil does not effect anything of itself, that is, as a privation, but by virtue of the good annexed to it. For every action comes from some form; and everything which is desired as an end, is a perfection. And therefore, as Dionysius says (Div. Nom. iv): "Evil does not act, nor is it desired, except by virtue of some good joined to it: while of itself it is nothing definite, and beside the scope of our will and intention."

Reply to Objection 5: As was said above, the parts of the universe are ordered to each other, according as one acts on the other, and according as one is the end and exemplar of the other. But, as was said above, this can only happen to evil as joined to some good. Hence evil neither belongs to the perfection of the universe, nor does it come under the order of the same, except accidentally, that is, by reason of some good joined to it.

Articulus 1

Argumentum 1

Ad primum sic proceditur. Videtur quod malum sit natura quaedam.

Quia omne genus est natura quaedam. Sed malum est quoddam genus, dicitur enim in praedicamentis, quod bonum et malum non sunt in genere, sed sunt genera aliorum.

Ergo malum est natura quaedam.

Argumentum 2

Praeterea, omnis differentia constitutiva alicuius speciei est natura quaedam. Malum autem est differentia constitutiva in moralibus, differt enim specie malus habitus a bono, ut liberalitas ab illiberalitate. Ergo malum significat naturam quandam.

Argumentum 3

Praeterea, utrumque contrariorum est natura quaedam. Sed malum et bonum non opponuntur ut privatio et habitus, sed ut contraria, ut probat philosophus, in praedicamentis, per hoc quod inter bonum et malum est aliquid medium, et a malo potest fieri reditus ad bonum.

Ergo malum significat naturam quandam.

Argumentum 4

Praeterea, quod non est, non agit. Sed malum agit, quia corrumpit bonum. Ergo malum est quoddam ens, et natura quaedam.

Argumentum 5

Praeterea, ad perfectionem universitatis rerum non pertinet nisi quod est ens et natura quaedam. Sed malum pertinet ad perfectionem universitatis rerum, dicit enim Augustinus, in enchirid., quod ex omnibus consistit universitatis admirabilis pulchritudo; in qua etiam illud quod malum dicitur, bene ordinatum, et suo loco positum, eminentius commendat bona.

Ergo malum est natura quaedam.

Sed Contra

Sed contra est quod dionysius dicit, IV cap. De div. Nom., malum non est existens neque bonum.

Corpus

Respondeo dicendum quod unum oppositorum cognoscitur per alterum, sicut per lucem tenebra. Unde et quid sit malum, oportet ex ratione boni accipere.

Diximus autem supra quod bonum est omne id quod est appetibile, et sic, cum omnis natura appetat suum esse et suam perfectionem, necesse est dicere quod esse et perfectio cuiuscumque naturae rationem habeat bonitatis.

Unde non potest esse quod malum significet quoddam esse, aut quandam formam seu naturam. Relinquitur ergo quod nomine mali significetur quaedam absentia boni. Et pro tanto dicitur quod malum neque est existens nec bonum, quia cum ens, inquantum huiusmodi, sit bonum, eadem est remotio utrorumque.

Ad 1

Ad primum ergo dicendum quod Aristoteles ibi loquitur secundum opinionem Pythagoricorum, qui malum existimabant esse naturam quandam, et ideo ponebant bonum et malum genera.

Consuevit enim Aristoteles, et praecipue in libris logicalibus, ponere exempla quae probabilia erant suo tempore, secundum opinionem aliquorum philosophorum.

Vel dicendum, sicut dicit philosophus in X metaphys., quod prima contrarietas est habitus et privatio, quia scilicet in omnibus contrariis salvatur, cum semper unum contrariorum sit imperfectum respectu alterius, ut nigrum respectu albi, et amarum respectu dulcis. Et pro tanto bonum et malum dicuntur genera, non simpliciter, sed contrariorum, quia sicut omnis forma habet rationem boni, ita omnis privatio, inquantum huiusmodi, habet rationem mali.

Ad 2

Ad secundum dicendum quod bonum et malum non sunt differentiae constitutivae nisi in moralibus, quae recipiunt speciem ex fine, qui est obiectum voluntatis, a qua moralia dependent. Et quia bonum habet rationem finis, ideo bonum et malum sunt differentiae specificae in moralibus; bonum per se, sed malum inquantum est remotio debiti finis. Nec tamen remotio debiti finis constituit speciem in moralibus, nisi secundum quod adiungitur fini indebito, sicut neque in naturalibus invenitur privatio formae substantialis, nisi adiuncta alteri formae. Sic igitur malum quod est differentia constitutiva in moralibus, est quoddam bonum adiunctum privationi alterius boni, sicut finis intemperati est, non quidem carere bono rationis, sed delectabile sensus absque ordine rationis. Unde malum, inquantum malum, non est differentia constitutiva; sed ratione boni adiuncti.

Ad 3

Et per hoc etiam patet responsio ad tertium. Nam ibi philosophus loquitur de bono et malo, secundum quod inveniuntur in moralibus. Sic enim inter bonum et malum invenitur medium, prout bonum dicitur quod est ordinatum; malum autem, quod non solum est deordinatum, sed etiam nocivum alteri.

Unde dicit philosophus in IV ethic., quod prodigus vanus quidem est, sed non malus.

Ab hoc etiam malo quod est secundum morem, contingit fieri reditum ad bonum; non autem ex quocumque malo. Non enim ex caecitate fit reditus ad visionem, cum tamen caecitas sit malum quoddam.

Ad 4

Ad quartum dicendum quod aliquid agere dicitur tripliciter.

Uno modo, formaliter, eo modo loquendi quo dicitur albedo facere album. Et sic malum, etiam ratione ipsius privationis, dicitur corrumpere bonum, quia est ipsa corruptio vel privatio boni.

Alio modo dicitur aliquid agere effective, sicut pictor dicitur facere album parietem. Tertio modo, per modum causae finalis, sicut finis dicitur efficere, movendo efficientem. His autem duobus modis malum non agit aliquid per se, idest secundum quod est privatio quaedam, sed secundum quod ei bonum adiungitur, nam omnis actio est ab aliqua forma, et omne quod desideratur ut finis, est perfectio aliqua.

Et ideo, ut dionysius dicit, IV cap. De div. Nom., malum non agit neque desideratur nisi virtute boni adiuncti; per se autem est infinitum, et praeter voluntatem et intentionem.

Ad 5

Ad quintum dicendum quod, sicut supra dictum est, partes universi habent ordinem ad invicem, secundum quod una agit in alteram, et est finis alterius et exemplar. Haec autem, ut dictum est, non possunt convenire malo, nisi ratione boni adiuncti. Unde malum neque ad perfectionem universi pertinet, neque sub ordine universi concluditur, nisi per accidens, idest ratione boni adiuncti.