1 Objection 1: It would seem that good cannot be the cause of evil. For it is said Mt. 7, 18): A good tree cannot bring forth evil fruit.
1 Ad primum sic proceditur. Videtur quod bonum non possit esse causa mali. Dicitur enim Matth. VII, non potest arbor bona malos fructus facere.
2 Objection 2: Further, one contrary cannot be the cause of another. But evil is the contrary to good. Therefore good cannot be the cause of evil.
2 Praeterea, unum contrariorum non potest esse causa alterius. Malum autem est contrarium bono. Ergo bonum non potest esse causa mali.
3 Objection 3: Further, a deficient effect can proceed only from a deficient cause. But evil is a deficient effect. Therefore its cause, if it has one, is deficient. But everything deficient is an evil. Therefore the cause of evil can only be evil.
3 Praeterea, effectus deficiens non procedit nisi a causa deficiente. Sed malum, si causam habeat, est effectus deficiens. Ergo habet causam deficientem. Sed omne deficiens malum est. Ergo causa mali non est nisi malum.
4 Objection 4: Further, Dionysius says Div. Nom. iv) that evil has no cause. Therefore good is not the cause of evil.
4 Praeterea, Dionysius dicit, IV cap. de Div. Nom., quod malum non habet causam. Ergo bonum non est causa mali.
5 On the contrary, Augustine says Contra Julian. i, 9): There is no possible source of evil except good.
5 Sed contra est quod Augustinus dicit, contra Iulianum, non fuit omnino unde oriri posset malum, nisi ex bono.
6 I answer that, It must be said that every evil in some way has a cause. For evil is the absence of the good, which is natural and due to a thing. But that anything fail from its natural and due disposition can come only from some cause drawing it out of its proper disposition. For a heavy thing is not moved upwards except by some impelling force; nor does an agent fail in its action except from some impediment.
But only good can be a cause; because nothing can be a cause except inasmuch as it is a being, and every being, as such, is good. And if we consider the special kinds of causes, we see that the agent, the form, and the end, import some kind of perfection which belongs to the notion of good. Even matter, as a potentiality to good, has the nature of good. Now that good is the cause of evil by way of the material cause was shown above Question 48, Article 3).
For it was shown that good is the subject of evil. But evil has no formal cause, rather is it a privation of form; likewise, neither has it a final cause, but rather is it a privation of order to the proper end; since not only the end has the nature of good, but also the useful, which is ordered to the end. Evil, however, has a cause by way of an agent, not directly, but accidentally. In proof of this, we must know that evil is caused in the action otherwise than in the effect.
In the action evil is caused by reason of the defect of some principle of action, either of the principal or the instrumental agent; thus the defect in the movement of an animal may happen by reason of the weakness of the motive power, as in the case of children, or by reason only of the ineptitude of the instrument, as in the lame. On the other hand, evil is caused in a thing, but not in the proper effect of the agent, sometimes by the power of the agent, sometimes by reason of a defect, either of the agent or of the matter.
It is caused by reason of the power or perfection of the agent when there necessarily follows on the form intended by the agent the privation of another form; as, for instance, when on the form of fire there follows the privation of the form of air or of water. Therefore, as the more perfect the fire is in strength, so much the more perfectly does it impress its own form, so also the more perfectly does it corrupt the contrary.
Hence that evil and corruption befall air and water comes from the perfection of the fire: but this is accidental; because fire does not aim at the privation of the form of water, but at the bringing in of its own form, though by doing this it also accidentally causes the other. But if there is a defect in the proper effect of the fire, as, for instance, that it fails to heat, this comes either by defect of the action, which implies the defect of some principle, as was said above, or by the indisposition of the matter, which does not receive the action of the fire, the agent.
But this very fact that it is a deficient being is accidental to good to which of itself it belongs to act. Hence it is true that evil in no way has any but an accidental cause; and thus is good the cause of evil.
6 Respondeo dicendum quod necesse est dicere quod omne malum aliqualiter causam habeat. Malum enim est defectus boni quod natum est et debet haberi. Quod autem aliquid deficiat a sua naturali et debita dispositione, non potest provenire nisi ex aliqua causa trahente rem extra suam dispositionem, non enim grave movetur sursum nisi ab aliquo impellente, nec agens deficit in sua actione nisi propter aliquod impedimentum. Esse autem causam non potest convenire nisi bono, quia nihil potest esse causa nisi inquantum est ens; omne autem ens, inquantum huiusmodi, bonum est.
Et si consideremus speciales rationes causarum, agens et forma et finis perfectionem quandam important, quae pertinet ad rationem boni, sed et materia, inquantum est potentia ad bonum, habet rationem boni. Et quidem quod bonum sit causa mali per modum causae materialis, iam ex praemissis patet, ostensum est enim quod bonum est subiectum mali. Causam autem formalem malum non habet, sed est magis privatio formae. Et similiter nec causam finalem, sed magis est privatio ordinis ad finem debitum; non solum enim finis habet rationem boni, sed etiam utile, quod ordinatur ad finem.
Causam autem per modum agentis habet malum, non autem per se, sed per accidens. Ad cuius evidentiam, sciendum est quod aliter causatur malum in actione, et aliter in effectu. In actione quidem causatur malum propter defectum alicuius principiorum actionis, vel principalis agentis, vel instrumentalis, sicut defectus in motu animalis potest contingere vel propter debilitatem virtutis motivae, ut in pueris; vel propter solam ineptitudinem instrumenti, ut in claudis. Malum autem in re aliqua, non tamen in proprio effectu agentis, causatur quandoque ex virtute agentis; quandoque autem ex defectu ipsius, vel materiae.
Ex virtute quidem vel perfectione agentis, quando ad formam intentam ab agente sequitur ex necessitate alterius formae privatio; sicut ad formam ignis sequitur privatio formae aeris vel aquae. Sicut ergo, quanto ignis fuerit perfectior in virtute, tanto perfectius imprimit formam suam, ita etiam tanto perfectius corrumpit contrarium, unde malum et corruptio aeris et aquae, est ex perfectione ignis. Sed hoc est per accidens, quia ignis non intendit privare formam aquae, sed inducere formam propriam; sed hoc faciendo, causat et illud per accidens.
Sed si sit defectus in effectu proprio ignis, puta quod deficiat a calefaciendo, hoc est vel propter defectum actionis, qui redundat in defectum alicuius principii, ut dictum est; vel ex indispositione materiae, quae non recipit actionem ignis agentis. Sed et hoc ipsum quod est esse deficiens, accidit bono, cui per se competit agere. Unde verum est quod malum secundum nullum modum habet causam nisi per accidens. Sic autem bonum est causa mali.
7 Reply to Objection 1: As Augustine says Contra Julian. i): The Lord calls an evil will the evil tree, and a good will a good tree. Now, a good will does not produce a morally bad act, since it is from the good will itself that a moral act is judged to be good. Nevertheless the movement itself of an evil will is caused by the rational creature, which is good; and thus good is the cause of evil.
7 Ad primum ergo dicendum quod, sicut Augustinus dicit, contra Iulian., arborem malam appellat dominus voluntatem malam, et arborem bonam, voluntatem bonam. Ex voluntate autem bona non producitur actus moralis malus, cum ex ipsa voluntate bona iudicetur actus moralis bonus. Sed tamen ipse motus malae voluntatis causatur a creatura rationali, quae bona est. Et sic est causa mali.
8 Reply to Objection 2: Good does not cause that evil which is contrary to itself, but some other evil: thus the goodness of the fire causes evil to the water, and man, good as to his nature, causes an act morally evil. And, as explained above Question 19, Article 9), this is by accident. Moreover, it does happen sometimes that one contrary causes another by accident: for instance, the exterior surrounding cold heats the body) through the concentration of the inward heat.
8 Ad secundum dicendum quod bonum non causat illud malum quod est sibi contrarium, sed quoddam aliud, sicut bonitas ignis causat malum aquae; et homo bonus secundum suam naturam, causat malum actum secundum morem. Et hoc ipsum per accidens est, ut dictum est. Invenitur autem quod etiam unum contrariorum causat aliud per accidens, sicut frigidum exterius ambiens calefacit, inquantum calor retrahitur ad interiora.
9 Reply to Objection 3: Evil has a deficient cause in voluntary things otherwise than in natural things. For the natural agent produces the same kind of effect as it is itself, unless it is impeded by some exterior thing; and this amounts to some defect belonging to it. Hence evil never follows in the effect, unless some other evil pre-exists in the agent or in the matter, as was said above. But in voluntary things the defect of the action comes from the will actually deficient, inasmuch as it does not actually subject itself to its proper rule. This defect, however, is not a fault, but fault follows upon it from the fact that the will acts with this defect.
9 Ad tertium dicendum quod malum habet causam deficientem aliter in rebus voluntariis, et naturalibus. Agens enim naturale producit effectum suum talem quale ipsum est, nisi impediatur ab aliquo extrinseco, et hoc ipsum est quidam defectus eius. Unde nunquam sequitur malum in effectu, nisi praeexistat aliquod aliud malum in agente vel materia, sicut dictum est. Sed in rebus voluntariis, defectus actionis a voluntate actu deficiente procedit, inquantum non subiicit se actu suae regulae. Qui tamen defectus non est culpa, sed sequitur culpa ex hoc quod cum tali defectu operatur.
10 Reply to Objection 4: Evil has no direct cause, but only an accidental cause, as was said above.
10 Ad quartum dicendum quod malum non habet causam per se, sed per accidens tantum, ut dictum est.