The principle of double effect

In order to provide a general rule of conduct in such circumstances, divines have formulated what is known as the principle of a double effect. That principle may be enunciated as follows: It is lawful to perform an action which produces two effects, one good, the other bad, provided that (1) the action, viewed in itself, is good, or at least indifferent; (2) the agent does not intend the evil effect, but only the good; (3) the good effect is produced as immediately as—that is, not by means of— the bad; and (4) there is a sufficiently weighty reason for permitting the evil effect.

This rule will furnish us with a guide in case of doubt whether we are bound to abstain from any given action because of some evil effect which will follow from it. We shall be at liberty to perform the action in question provided that four conditions are realized. In the first place, the action itself, apart from the evil effect, must not be bad. If it is bad in itself, there can be no question about its lawfulness. Further, the agent must not intend the evil effect, though he foresees that it will follow. If he intends it, the evil effect becomes voluntary in itself and imputable to the agent. Then, the good effect must not be the result of the bad, for we must not do evil that good may come; the end does not justify the means.1 Lastly, there must be such a proportion between the good and bad effects that right reason tells me that I am not forbidden to forego the good effect of the action on account of the bad being inextricably bound up with it.

The question as to whether a general is justified in ordering his army to take a stronghold by assault in war will serve to illustrate the principle and its use. In the first place, the assault must be justified by itself, apart from the cost in human life. The assault will be justified in itself if the war is just and the stronghold belongs to the enemy; it will not be justified if the war is one of unjust aggression, or if the general has been expressly ordered by his Government not to take the place. Moreover, the general must not directly intend the necessary loss of life among the innocent non-belligerents.

He foresees and deplores it; he is said in the technical language of theology to permit the evil effect, not to intend it. The slaughter of innocent non-belligerents must not be the means chosen to capture the stronghold; evil may not be done that good may come. Finally, the capture of the place must be a matter of sufficient importance in the war to warrant the shedding of innocent blood in the bombardment, and the other evils necessarily entailed in an assault. The question as to when the good result is sufficient to outweigh the evil is largely a matter of sound judgement after a careful examination of all the circumstances. If the successful storming of the place would only add to the personal reputation of the general without bringing the end of the war any the nearer, the assault would be a crime; if it would compel the enemy to sue for peace, it would usually be justified. This principle is of great importance in Moral Theology; it has in its support the common consent of divines, and is expressly used by St Thomas.”

The death of the innocent may be permitted, not intended, when it follows from some action lawful in itself which also produces an equally immediate and good effect, and when this counterbalances the evil effect. This, again, is but the application of the principle of a double effect, and it is evident from what has been said before. The general of an army who orders the bombardment of a beleaguered town knows that his order cannot be executed without killing perhaps many innocent non-combatants, yet the action is not unlawful.

What is required so that an evil effect which follows, voluntary only in the cause or indirectly, be imputable to the will as fault? - The following conditions are required: 1. That he who posits or omits the cause advert, at least confusedly, that such an effect will follow from that cause; because nothing is willed unless in some way it is known beforehand.

2. That the agent be able to impede such a cause; because there is no obligation to impossibilities.

3. That the agent be bound, by reason of that effect, to remove or omit that cause; because the effect following outside the intention is not imputed to one pursuing his own right. For then the agent in reality does not will the effect, but wills the permission of the effect. L. 1. 5. n. 15; S. Th. 1. 2. q. 6. a. 3; q. 21. a. 2; C. I. 1151 f.; C. G. 1182 f.; C. H. 1092 ff.

When is someone bound to remove the cause, by reason of an evil effect that will follow? - 1. He is bound when it of itself, directly and primarily, produces nothing except an evil effect. For then the cause is evil in itself. It is said, of itself, directly and primarily, produces nothing except an evil effect, because one would not therefore be bound to remove the cause if the evil effect followed merely accidentally; for then the cause would not therefore be evil in itself. Nor would he be bound if the cause of itself, directly and primarily, produces a good effect, and only through this as a medium an evil effect follows; for a cause according to moral estimation is judged from its effect of itself, directly, and primarily, and accordingly it is then simply honorable in itself. Therefore then one would not will the evil, but would will the good, and would only permit the evil. Likewise one would not therefore be bound to remove the cause because it equally, directly and primarily, as if in a parallel manner, influences a good and an evil effect. For then the cause in itself, according to moral estimation, is indifferent, and honorable, insofar as it is subject to the honorable intention of the agent; for the evil effect is not intended, but permitted. S. Th. 1. 2. q. 20. a. 5; q. 73. a. 8; 2. 2. q. 64. a. 7.

2. Someone is likewise bound to remove the cause by reason of an evil effect that will follow, when, although the cause is honorable or indifferent in itself, nevertheless someone is bound to impede the effect from justice, or from charity, or from a precept that presses to be fulfilled; for example, if someone wished to play for the sake of recreation while the last Mass on Sunday will soon be celebrated, so that consequently he omits it from distraction. "For he who is bound to the law must necessarily be bound to procure the ordinary means, and the means proximately necessary from the very nature of the thing, for observing the law..... Ordinary, I say; for human laws do not compel to extraordinary and excessively difficult things." Ithur., case 32, n. 4. Hence "the reason can be given, that by reason of the precept that cause and the effects following from it, although physically they are connected only accidentally, and one is not the cause of the other, nevertheless morally are judged to have the notion of one unsuitable object, or one to be avoided by the will, and therefore the will of one is judged the virtual will of the other." Suarez, tr. 2, d. 1, s. 4, n. 9.

3. Finally, someone is bound to remove the cause by reason of an evil effect that will follow, when, although the cause is honorable or indifferent in itself, nevertheless there is no proportionate necessity, utility, or fittingness on the part of the agent. For then an honorable end of the one operating is lacking; for evil is to be avoided, and it can be permitted when there is a rational and just cause. Besides, to will such a cause then often shows an evil affection directly toward that evil effect that will follow; or at least there is often a proximate danger of such evil affection. But a greater or lesser reason is required for positing the cause according as it is a cause of itself, or from its own nature influencing such an effect, or an accidental cause, namely one which does not influence such an effect from its intrinsic nature, but from some extrinsic condition of things. Likewise the greater reason is required for acting in such a case, the more proximately the cause touches the evil effect, the more probable the evil effect is, the less right one has to the action considered in itself, and the graver the effect itself is, if one is bound by office to impede the evil. For if a proportionately grave reason is not had, natural honesty itself obliges us to omit that cause. L. 1. 1. n. 152; l. 5. n. 14; S. Th. 2. 2. q. 64. a. 7.

Is the effect which follows, gravely evil, voluntary only indirectly or in the cause, always imputable as grave fault, so that someone contracts the grave malice proper to that effect, if he illicitly posits the cause without any sufficient reason? - R. 1. Affirmatively, if that cause of itself, or from its intrinsic nature, gravely influences the effect. The reason is that if the cause of itself gravely influences the effect, the grave malice from the effect redounds into the cause. Therefore someone contracts the grave malice proper to the effect itself by willing its cause without any sufficient reason. Moreover, at least practically speaking, one who wills the cause, of itself gravely influencing an effect gravely evil, without any sufficient reason, in reality directly wills the grave malice of that effect, and does not merely permit it; since the cause and effect are inseparably connected with one another, so far as concerns the very nature of the thing, and no other honorable reason is present for positing the cause on account of another honorable effect, as is supposed.

R. 2. Negatively, if that cause of itself influences that effect only lightly. The reason is that, since the cause of itself has only a light influence upon that gravely evil effect, a cause of this kind is not of itself sufficient for the positing of the effect, and accordingly, so far as concerns the nature of the thing, they are not inseparably connected with one another. Therefore it is not the case that because someone wills the cause, he also wills the effect, but he wills only the permission of the effect, if perhaps it follows. Accordingly he does not contract the grave malice proper to the effect. But since the malice of the effect redounds into the cause by reason of the influence which the latter has upon the effect, where the influence is light there is only light malice; and consequently, with the direct intention of the gravely evil effect always excluded, someone willing a cause that influences such an effect only lightly, although he will not sin gravely, nevertheless will sin lightly. And this is the proper reason why, although there is no smallness of matter in venereal matters, nevertheless there is such in those acts of mere sensuality, as are looks, from a cause of mere curiosity, at less honorable things, with the intention of the venereal thing itself again excluded, as the very common opinion of theologians holds.

R. 3. Again negatively, if the cause in no way of itself influences that evil effect, but the effect follows merely accidentally, or from extrinsic circumstances. The reason is that since the effect follows only accidentally, there is no connection, so far as concerns the nature of the thing, between the cause and the effect. Therefore it is not the case that because someone wills the cause, he also wills the effect, but he wills only the permission of the effect, if perhaps it follows. But since the malice of the effect in no way redounds into the cause, for the effect does not follow from that cause of itself, but merely accidentally, someone willing the cause, with every intention of the evil effect excluded, contracts none of its malice, neither grave nor light, although perhaps otherwise he also sins gravely. And thus, if someone foresees pollution from some excess of drink or food, without willing and intending it, he will sin lightly, or perhaps even gravely, by reason of that excess, but by no means will he sin by reason of the pollution, since this effect is not willed, but happens outside and against the intention, and the cause is outside the genus of lust. Nor indeed is someone bound to remove all causes influencing only accidentally into some evil effect, by reason only of that evil effect itself. For in actions only this one thing must be attended to: whether they are the cause of this effect, or not. For if they do not have the force of a cause, it is ridiculous that they must be avoided on account of an effect of this kind. And in no way is someone bound to abstain from positing such a cause, if a reasonable motive is present for positing a cause of this kind.

Cf. 40. 1, 4; Suarez, tr. 2, d. 1, s. 4, 5; Sanchez, l. 9, d. 45, n. 14 ff.; L. 1. 3. n. 484; Salm., tr. 26, c. 7, n. 41; S. Th. 2. 2. q. 154. a. 5; 3. p. q. 30. a. 7; d'Annibale, 4th ed., p. 1, n. 157, note 15.

9. • II. Principle. It is lawful to posit a good or indifferent cause from which immediately follows a twofold effect, one good and the other evil, if there is present a proportionately grave cause, and the end of the agent is upright, namely, he does not intend the depraved effect. - St. Thomas, II-II, q. 64, art. 7.

The reason of this principle is that if this were not lawful, the agent would sin either from the intention of the depraved effect, or from the positing of the cause, or from the foreseeing of the evil effect. But none of these can be said.

For 1. this is not illicit by reason of the end, since it is supposed upright; 2. nor by reason of the apposition of the cause, since it is supposed good, or at least indifferent, or even if it is evil, nevertheless it is not evil on account of that effect about to follow; 3. nor from foreseeing the depraved effect, for in the hypothesis this is not intended, but merely permitted; and for permitting it there is present a proportionately grave and just cause.

But four conditions which are enunciated in this principle are altogether required, namely: 1. that the end of the agent be upright; 2. that the cause be good, or at least indifferent; 3. that the good effect be immediate; and 4. that there be present a grave reason for positing the cause, and that the agent not be held from justice, or from office, or from charity to omit it.

Therefore 1. a good end is required, that is, the agent ought not to intend the evil effect, because otherwise the evil effect would be voluntary in itself. For this reason neither ought he in any way to take complacency for himself concerning the depraved effect.

2. A good cause is required, or at least an indifferent one, namely, that the act be opposed to no law ¹. The reason is evident. For if the cause were evil in itself, it would introduce guilt per se.

¹ This statement extends more broadly than is proper. And indeed, he who unjustly kills a man posits a cause, on account of which creditors suffer harm, evil, indeed most evil; nor nevertheless is he therefore held to restitution, unless he intended that harm, according to the common opinion of the Doctors. Therefore the guilt to be considered here is not that which inheres in the cause in itself on account of opposition to any law whatever, but that which arises from the obligation of guarding against that effect.

3. It is required that the good effect follow at least equally immediately from the cause. The reason is that if the cause directly and immediately has a depraved effect, and the good effect comes only by means of that depraved effect, then good is sought from evil: but it is never lawful to perpetrate evil, however slight, for procuring any good whatsoever; for according to the very common axiom drawn from the Apostle, Rom. 3:8: Evil things must never be done that good things may come. Thus it is not lawful for you to lie, even to save the life of a man.

4. It is required that there be present a proportionately grave reason for positing the cause; because natural equity obliges us to avoid evils and to guard against harms to our neighbor, when we can do this without proportionately grave harm ².

² Here, however, one must not weigh only the harm or inconvenience of the agent at that time, but also and much more the common inconvenience of all, if this were generally required.

Now in these cases, the greater the reason required for acting, the more nearly the cause touches the evil effect, the more probable the evil effect is, and the less right one has to the action considered in itself.

Preliminary note. The doctrine concerning the indirect voluntary or voluntary in the cause is of the greatest moment for practice and is, as it were, a key by which many and difficult cases must be solved, for example, concerning cooperation, scandal, the causing of damage, etc. But since these things come chiefly into use in evil effects which are indirectly voluntary, now for the sake of brevity we treat only of the evil indirectly voluntary. For if the indirectly voluntary is something good, then either a) it is joined with another good effect, and thus each effect remains good and the goodness of the whole is increased, or b) it is joined with another (principal) evil effect, and thus the whole, notwithstanding the secondary good effect, becomes evil according to the adage: Good is from an integral cause, evil from any defect whatsoever. - Human actions, although they are singular, often have several effects; for they are after the manner of the motion of some wheel in an artful machine. If one wheel is moved, the others also receive an influx. Thus, for example, a father of a family laboring diligently procures for himself wages, honor among his fellow-citizens, love with his wife, internal peace, etc.; conversely, a father of a family getting drunk causes for himself material losses, quarrels in the family, scandal for his children, etc. Hence it is clearer than light how great is the moment of the doctrine concerning the morality of several effects following from one cause.

57. Principle. It is permitted to posit an action good or indifferent in itself, of which there is a twofold or multiple effect, namely, one or another good effect and one or another evil effect, if:

1. the good effect is immediate;

2. the end of the agent is honest;

3. there is a proportionately grave cause.⁴⁴

The same principle can also be enunciated in this way:

Four conditions are required in order that the evil indirect voluntary be licit: 1. an action good in itself or at least indifferent; 2. the immediate effect good; 3. an honest end; 4. a proportionately grave cause.⁴⁵

It is explained: 1. Before all else it is required that the action posited be good in itself or at least indifferent. Wherefore it is never permitted to perform actions evil in themselves, such as, for example, to lie, to blaspheme, to fornicate, etc., although the best effect is hoped for from them. The reason is that evils are not to be done that goods may come. - But for judging theoretically whether an action is good or indifferent in itself, one must first look to the end of the work or the moral object to which the action from its own nature and immediately is ordered. For acts, as the scholastics teach, are specified from the moral object. But I say moral object and not physical, because one and the same physical act perpetrated by diverse persons can have a diverse moral object, but not a diverse physical object. Thus, for example, to kill a man is an act whose physical object is the violent destruction of human life; this object indeed does not morally specify the human act, but can be either morally good, if, for example, the killing was done by a soldier in a just war, or morally evil, if, for example, a man is killed in an unjust manner. - For judging in practice whether some action is good or indifferent in itself, it helps to inspect whether the agent, absolutely speaking, has the right of positing this action and does not injure the right of another. Thus, for example, an innkeeper has the right of serving wine; an owner has the right of renting his house; and therefore these actions are good, although accidentally they are joined with the evil effect of drunkenness or prostitution.

⁴⁴ Cf. St. Thomas, S. theol. II-II, q. 64, a. 7.

⁴⁵ Cf. Marc-Raus, Inst. mor. I, n. 315; Noldin, De principiis n. 83.

58. 2. Then it is required that the good effect be immediate, that is, that the evil effect not precede it, but follow it. This is plain from the text of St. Paul: "Let us not do evil things, that good things may come."⁴⁶ For this reason it is not permitted to steal money from a very rich man in order to give alms to a poor man; it is not permitted to kill an infant in the mother's womb in order to save the mother's life; a girl pregnant from a crime cannot licitly procure an abortion in order to save her honor. Besides, this condition seems almost to coincide with the first. For if the first effect is morally evil, the action itself also, which produces this effect, is morally evil in itself. For an action is specified from the object or end of the work, as will be proved below. But the end of the work is that which the work first produces, or is the first effect of the action.

But if many authors teach that it suffices that the good effect be equally immediate as the evil effect, this seems to be impossible, at least in practice, because the immediate effect is the end of the work. But the end of the work is one and not twofold, just as the essential form of any one thing is one and not twofold. Nor is any example brought forward by those authors in which truly the good and evil effect are equally immediate. On the contrary, the good effect always precedes or is preceded. Hence the Angelic Doctor forcefully proclaims: "The same act in number, insofar as it once goes forth from the agent, is not ordered except to one proximate end, from which it has its species."⁴⁷ Since these things are so, it seems better to me to express the second condition in this way, if it is to be expressed: it is required that the good effect follow per se and as if necessarily, but the evil effect only per accidens from such an action, namely, because of particular circumstances which occur to the agent against his will. Thus, for example, an innkeeper can for a grave reason sell wine to him who is now about to become drunk. Why? Because the effect which follows per se and necessarily from the sale of wine is licit commerce and honest profit; but that in these circumstances, which do not depend on the innkeeper, some evil follows, namely, the drunkenness of the drinker, this is altogether per accidens, nor is it necessarily joined with the sale of wine, although here and now that evil effect is infallibly produced.

⁴⁶ Rom. 3:8.

⁴⁷ S. theol. I-II, q. 1, a. 3 ad 3.

59. 3. Moreover it is required that the end of the agent be honest. For although a good end does not render evil means honest, nevertheless an evil end defiles all things, whatever means have at last been employed.⁴⁸ Therefore the agent is bound to intend only a good end; but he can bear himself permissively toward the evil effect foreseen. For example, a confessor hearing most shameful sins in the confessional feels grave temptations and dishonest carnal movements. Nevertheless he licitly hears confessions of this kind, provided, however, that he intends a good end, namely, the salvation of the soul, the honor of God, etc., and bears himself only permissively toward those evil effects, which he not only does not seek, but detests. On the contrary, it is not licit to dig a pit on one's own land with the (inordinate) intention that an enemy may fall into it and be gravely injured. For although to dig a pit on one's own land is a good or indifferent action, nevertheless the intended end is dishonest.

⁴⁸ Cf. below n. 121 sqq.

60. 4. Lastly it is required that there be a proportionately grave cause for acting and permitting the evil effect. For the evil effect, although it is joined with the work of the agent beside the intention, always remains a material sin; indeed not rarely it induces grave danger of formal sin. Further, it is not licit to effect material sins, and especially it is not licit to expose oneself to the danger of formal sin, without a proportionately grave cause. I say proportionately grave; for the greater the malice of the effect is, the greater the excusing cause required. But what cause in a particular case is truly proportionately grave must not be weighed from one point. One must consider the circumstances. First, it must be seen whether from the omission of the action which produces two effects, one good and the other evil, some notable harm would truly follow. If not, the action must be omitted; for example, a bookseller who does not offer some dangerous book in his shop indeed loses a small profit, but he does not suffer notable harm. In this case the merchant must desist from such a sale. - On the contrary, if great harm would follow from the omission of the action, it is permitted to complete the action; for example, a confessor experiences vehement temptations; nevertheless he is not bound to desist from hearing confessions, because otherwise great harm would arise for him. - Then it must be seen whether the cause produces the evil effect proximately or only remotely. In causes proximately influencing, a greater motive is required than in those acting remotely. Thus, for example, a very urgent cause is required so that a maidservant may be able to exercise service in some house in which she is often allured to sin by the son of the family; but a much lesser motive would suffice if not the son of the family, but some stranger not so frequently coming into this house, were soliciting her to sin. Generally it can be said: A greater excusing cause is required in proportion as

1. the evil indirectly willed is more grave;

2. the action influences this evil more nearly;

3. the evil truly follows more certainly;

4. the obligation from office of impeding this following evil is greater.

61. Resolves: 1. Soldiers who in a just war attack a city licitly discharge war-cannons, even if from this innocent private persons perish. The reason is that the action, namely, the discharge, is just; the end of the agent is good, namely, the punishment of the enemy; and finally there is a proportionately grave cause.

2. A priest who from confession alone knows that some man is in the state of mortal sin licitly gives communion to him asking for it. The reason is that to give communion is a good action; the end of the priest is good, just as there is also a proportionately grave cause, namely, the preservation of the sacramental seal.

3. A physician who, in treating a sick woman, suffers grave temptations and carnal movements, can licitly continue the care, if a proportionate cause exists. The reason is that the curative action is honest, the end is honest, and a proportionate cause is present. Likewise a physician can, from a proportionate cause, administer medicine necessary for obtaining the health of a pregnant woman, although he foresees that an abortion will follow per accidens. The reasons are the same. But it is never permitted directly to procure an abortion, since this is the direct killing of an innocent man and therefore an intrinsically evil action.

4. A witness cannot perjure himself in order to save the life of the accused. The reason is that to perjure oneself is an intrinsically evil action.

5. A wife cannot render the conjugal debt to an onanist husband unless there is a grave cause. The reason is that although to render the conjugal debt is a good act and the wife's end is right, nevertheless without grave cause it is not permitted to cooperate materially so proximately with the sin of another.

62. Scholion. Several authors, speaking of an evil effect indirectly voluntary, add other conditions, namely, that the agent then only is bound to avoid the evil effect, or that then only the evil effect is imputed to him, if a) he foresaw (at least confusedly) the evil effect; b) if he was able not to posit the cause; c) if he was obliged not to posit the cause. But the first and second condition are verified not only in the indirect voluntary, but in any act whatever done by man. For an effect which he did not foresee, or whose cause he was not able to avoid, is never imputed to the agent. The reason is that in each case the free voluntary is lacking. But the third condition is precisely the point of the question. For our investigation turns on this alone: when a man is bound not to posit a cause from which a twofold effect follows, one good, the other evil. Since these things are so, those three conditions are better omitted in the explanation of the indirect voluntary.

S. Th. I-II, q. 77, a. 7; q. 20, a. 5; II-II, q. 43, a. 3; q. 46, a. 2, ad 2; q. 64, a. 7 and 8; q. 79, a. 3, ad 3; q. 150, a. 4.

62. Notions. - By reason of the mode in which the will is borne toward it, the positive and direct voluntary is either:

1. Voluntary in itself, when the will is directly borne toward it, that is, immediately wills something in itself and at the same time causes it by acting, whether as an end (on account of itself), for example when someone wills to kill an enemy, or as a means to an end (on account of another), for example when a thief wills to kill a traveler in order to take money; or

2. Voluntary in cause only, when the will is immediately borne toward the cause and not toward the effect, that is, it does not will the effect in itself as end or means, but nevertheless that effect proceeds from the will insofar as the will wills and does something else with which it is joined as with a cause, for example when someone wills to become drunk, foreseeing that in drunkenness he will commit blasphemies, impurities, homicide. The cause can be physical or moral, immediate or mediate, proximate or remote, a cause per se which is apt to produce the effect although by accident the effect can fail (thus excessive drinking produces drunkenness), or a cause per accidens which not from its nature but by the intervention of another can sometimes produce it (thus drunkenness, when a quarrel intervenes, produces homicide).

1. Hence it exists only in rational creatures, because it supposes it to be known how one thing follows from another.

The more commonly received prefer to say direct and indirect voluntary; but they would speak better if they said immediate and mediate: for that which proceeds from the will through a positive cause nevertheless proceeds directly from it.

2. Therefore the voluntary in cause, which many more recent authors call indirect, is called direct by St. Thomas, because it is from the will as acting. I-II, q. 77, a. 7.

63. Principles. In order that an effect be voluntary in cause, it is required:

1. That the effect was foreseen in some way, at least confusedly, as was said in no. 60, II: for nothing is willed unless it is foreknown;

2. That it could have been avoided, and therefore that the cause was freely placed or could have not been placed: for the effect is not more voluntary than its cause;

3. That there be a nexus of causality between this freely placed cause and this effect. This:

a) is always verified of a cause per se if the two prior conditions are present: for he who wills the cause is judged to will the effect which naturally and necessarily follows from it;

b) is also verified of a cause per accidens, provided that, besides, there is a third condition: that the effect ought to have been avoided, or that there was an obligation not to place the cause, and indeed not to place it lest the effect follow. For since the effect is not sufficiently contained in such a cause (except by means of another cause), and therefore there is no physical nexus with the effect, if the said obligation is lacking, every nexus of causality, even moral, between cause and effect is lacking, and therefore the effect will not be willed nor voluntary in cause, but only permitted. On the contrary, if someone is bound not to place the cause lest the effect follow, and nevertheless places it, he is morally judged, and imputably is, the cause of this effect.

But if the aforesaid conditions are present, the axiom is verified: An evil effect foreseen in the cause communicates its malice to the cause, namely, if it itself can and ought to be avoided. For an effect voluntary only in the cause is not imputed for praise, because it is not intended; but for it to be imputed for fault, it is required that there be an obligation of avoiding the cause lest the effect follow; otherwise no precept regarding the effect would be violated.

64. Corollaries.

From the aforesaid things it follows:

1. That an effect voluntary in the cause can be in itself non-voluntary, if it is not intended, indeed involuntary in itself, if it displeases, as if someone places the cause of killing (for example, to shoot an arrow with some foresight of killing) and the killing is not intended or displeases him, for example, if he does not will to kill but wills to shoot the arrow without employing sufficient diligence lest he kill a man.

2. On the contrary, that an effect can be willed in itself, if it pleases, is desired, or even intended, and not voluntary, if it follows from a cause per accidens and the obligation of avoiding it is lacking because, for example, a greater good effect which follows from the cause is also intended. For then the evil effect willed in itself is not voluntary, but only permitted in the cause (cf. n. 173).

Thus if someone digs a pit on his own land, remote from the road, foreseeing and desiring that his enemy could fall into it; if this happens, the fall is not voluntary to him, because he was only its cause per accidens.

3. That an effect, for example the sin of a neighbor, of which we in no way place the cause per se but only a mere occasion or condition or cause per accidens, is not voluntary in the cause nor imputable, even if it is willed and intended in itself, unless nevertheless there is an obligation of avoiding the effect: for our intention does not change an occasion into a cause, nor a cause per accidens into a cause per se.

Thus if someone takes from a miser a thing of slight value, foreseeing or even intending that from grief he may become ill or die, and this happens, the illness and death are not voluntary, because he was their mere occasion or cause per accidens, in no way their cause per se.

173. Principle concerning the licit mode of causing an evil effect. - Each virtue generally obliges one to avoid the cause which produces an evil effect opposed to it, for example, harm to a third party, scandal, dishonorable movements; yet not always. It is licit to place a cause which produces at the same time a good and an evil effect, if the good effect follows at least as immediately from the cause as the evil, or not by means of the evil, and there is a proportionately grave reason, with two other things always necessary presupposed, namely, an action licit in itself and a right intention of the agent.

Therefore four things are required: a) two on the part of the effect, so that the evil effect is not imputed; namely:

1. that the good effect follow at least as immediately from the cause as the evil, or not by means of the evil effect; otherwise the latter would be the means for obtaining the good effect, although evil things are not to be done that good things may come (n. 156, 5): hence it is illicit to lie in order to save a man, to procure abortion in order to avoid infamy, or to kill the fetus in order to save the life of the mother, to steal money in order to give alms, etc.

2. That there be a reason for placing the cause, and indeed a proportionately grave one, that is, that the good procured surpass or equal the evil: for reason dictates that a lesser good is not to be procured by an act from which a greater evil follows; on the contrary, if the good compensates the evil, no reason now appears why the evil ought to be avoided: thus it is not licit to kill an invader in order to preserve goods of lesser price; it is licit in order to preserve life. Hence the greater the malice of the effect, the greater must be the excusing reason; and it is always required that the good effect cannot suitably be obtained otherwise, for otherwise there would no longer be a reason for bringing on the evil effect.

b) That not only the evil effect not be imputed, but also that it be caused licitly, or that the action itself be honorable, two other things are further required on the part of the action:

3. That the action in itself (that is, setting aside the circumstances) not be evil, but honorable or at least indifferent: for a cause evil in itself per se includes fault.

4. That the end of the agent be honorable, and therefore that the evil effect not be intended but only the good; otherwise the evil would be voluntary in itself or at least willed. Hence it is also required that there be no proximate danger of consenting to the evil or approving it.

1. Vermeersch well notes, Th. M. I, n. 133, that one must take care not to apply the rule stated concerning a twofold effect, good and evil, caused simultaneously, to the diverse case of an action which can be this or that, for example, that which I see is perhaps a man, perhaps a beast. The voluntary discharge of a gun at that thing will be perhaps homicide, perhaps useful hunting. Here it is not a question of partial causality into a harmful effect which nevertheless is not imputed on account of a proportionate reason of a good simultaneously caused; or, by full causality, one of two things disjunctively comes about. Therefore homicide is hypothetically accepted and chosen: it is one probable evil effect. For this reason it is no more licit to inflict it upon a probable man than upon a certain man.

Yet this principle is not always rightly explained by all.

a) Some assert that it is not required that the good effect be immediate, but that it suffices that it not come about by means of the evil, even if it is more remote. But this seems to be a question about the mode of speaking: for then the possibility of obtaining the good effect already results immediately from the action, and this already is a certain good effect.

b) Others understand the principle only of a cause per se as to the good effect and of a cause per accidens as to the evil effect, so that the good effect ought to follow per se and as it were necessarily from the action, and the evil effect only per accidens. But although in this case there can more easily be a reason for placing the action, or compensation of the evil effect by the good, nevertheless it is not proved that this is a condition without which not, so that otherwise one would have to abstain from the action. For it does not seem impossible that there be a cause from which there would follow simultaneously per se a twofold effect: one good, the other evil (suppose health, and drunkenness or abortion); which nevertheless it would be licit to employ if it were necessary for obtaining the good effect, provided that this compensates the evil. Indeed, if the evil effect followed per se from the cause, and the good merely per accidens, why could we not order that cause per accidens to obtaining the good effect, if in this way it is certainly produced and truly outweighs the evil? Therefore by such a restriction they seem to limit the principle unduly.

c) Finally, others apply the principle too materially, and seem to think that the good effect considered in itself must always be equal to the evil effect. But it suffices that the goodness of the effect, together with the utility which it procures for the agent or others, and the inconvenience and damage avoided (which would arise if the cause were not placed), compensate the evil, that is, not always the evil effect but at least the influence of the action upon this effect: for the evil effect must be compensated by the agent because his action influences it; whence it must be compensated insofar as the action influences it. Hence a graver reason for placing the cause is required:

1. the graver or worse the effect is, both in itself and with respect to the harm of others, especially of society; for example, a greater cause is required for killing an aggressor than for slightly wounding him, greater for producing an effect harmful to society than to an individual;

2. the more actively and necessarily the evil effect proceeds from the action, the more closely it coheres with it, and the more probably it follows from it; for example, a greater reason is required in one who concurs proximately, a lesser in one who concurs remotely, in the sin of another (for example, the making of a bad book or drunkenness); greater for reading a bad book than a book of lighter character from which movements of concupiscence more remotely arise; greater for placing a cause per se than a cause per accidens. Likewise a very urgent cause is required for a maidservant to be able to exercise service in a house where she is often enticed to sin by the son; a much lesser motive suffices if an outsider coming into the house at times solicits;

3. the less right the agent has to place the cause and the more certain it is that, if he does not act, the effect will not be produced; in other words, the greater the obligation from office of impeding the evil. For example, a greater reason is required for renting a building to heretics if they can find no other than if they can easily rent one; a greater reason for a bookseller to be able to sell a bad book if no other seller is found who will give it, than if another will sell it.

All these things are to be considered together so that it may prudently be estimated whether the good compensates the evil.

177. Corollary. - From what has been said it is understood why and how far it is illicit voluntarily to expose oneself to danger of acting badly or sinning: for this is not sufficiently avoiding the evil effect, or even it is placing the cause of an evil effect. That danger can be from an internal cause (as is a depraved imagination or passion) or an external one (namely, an occasion, such as a thing enticing to evil); absolute, that is, commonly for all, or relative to such a determinate person; proximate or grave, which in many cases or at least frequently is connected with sin, or remote or light, which is rarely connected. Now:

1. It is illicit without a just and proportionate reason to expose oneself to a proximate or grave danger of acting badly. For one who without sufficient reason wills a thing, by that very fact imputably wills everything which is probably connected with it, and therefore one who intends to incur the danger of acting badly, by that very fact wills the evil probably connected with it. And one who is bound altogether to avoid sin is also bound to avoid the means which probably leads to it. Hence one who does not avoid such a danger, when he can, is convicted of not sufficiently avoiding but loving that evil whose danger he loves (Eccli. III, 27). Hence everyone is bound under grave obligation to avoid a proximate danger of committing a grave evil; a proximate danger of committing a light evil, under light obligation.

2. It is licit from a just reason proportionately grave, namely, of a compensating good effect, to expose oneself to the danger, even grave and proximate, of acting badly. The reason is that one who from a just reason exposes himself to danger does not love the evil, but the good cause on account of which he so acts, nor properly exposes himself to danger, but rather unwillingly undergoes the danger. Understand this with the restriction: provided there is a founded hope of overcoming the danger and suitable precautions are applied for this, by which the danger becomes remote; for certain sin is absolutely to be avoided.

313. Things to be noted beforehand. For a right understanding of the things which follow, certain notions concerning cause and effect must be premised (II, 63 seqq.; III, 571).

A. A multiple CAUSE is distinguished:

1. By reason of influence, it is physical or moral. Physical is that which acts through a physical influence, as fire produces conflagration, the sun light. Moral is that which efficaciously moves another free cause to acting. Thus one commanding homicide is a moral cause of the killing.

2. By reason of mode, it is immediate or mediate. Immediate is that which produces the effect with no other cause intervening: for example, if someone pierces the breast of another, he is the immediate cause of his death. Mediate is that which does not produce the effect except with another cause interposed. Hence, if you except the sin of scandal, a moral cause is always a mediate cause.

3. By reason of connection with the effect, it is proximate or remote. Proximate is said of that which has a necessary, or at least ordinary, connection with the effect which it produces for the most part: for example, poison, administered in an undue quantity, is a proximate cause of death. That is called remote from which the effect, for the most part, does not occur: for example, the reading of a slightly base thing is a remote cause of pollution.

4. By reason of the order of production, there is given a cause per se or per accidens. A cause per se is that which by its nature tends or is ordered to producing the effect: thus excessive drink is a cause per se of drunkenness. A cause per accidens is that to which an effect is joined beyond the ordination of nature. Thus homicide can follow from drunkenness.

Especially to be kept before the eyes are the two latter distinctions, which give place to a fourfold hypothesis, because both a cause per se and a cause per accidens can be proximate and remote (cf. n. 315).

B. The EFFECT is voluntary either directly and in itself, or indirectly and in the cause (cf. n. 272, 7). Now, an effect voluntary in itself is certainly to be morally imputed, since it is truly intended by the will. An effect voluntary only in the cause cannot be imputed to good: for goodness is not contracted unless it is intended (cf. n. 309, II); but an effect of this kind can be morally evil and be imputed to fault. When this happens will be clear from the following principles.

314. PRINCIPLES. I. An evil effect, voluntary only in the cause, is imputable to fault when it is foreseen as going to follow in such a way that it could and ought to have been impeded, and nevertheless is not impeded. Therefore three things must concur, namely:

1. That the effect was foreseen, at least confusedly. The reason is because if it was in no way at all foreseen, it was not voluntary; for nothing is willed unless foreknown. Hence neither is it voluntary, nor imputable to fault, when drunkenness follows from a moderate drinking of wine whose intoxicating force was unknown. On the contrary, blasphemies, quarrels, obscene speeches, which are accustomed to accompany the drunkenness of wine-drinking men, are voluntary and imputable as sin. For that such things would occur is sufficiently clear from experience.

2. That the effect could have been impeded, that is, that it was in the power of the agent either not to posit the cause, or to remove it once posited: for with liberty lacking, the voluntary lacks; nor is there ever any obligation concerning the impossible. Hence a priest is not guilty of sacrilege who gives Communion to a hidden sinner publicly asking it; for the cause of the sacrilege which is committed, in such circumstances, he cannot fail to posit.

3. That the effect ought to have been impeded, that is, that the agent is bound not to posit the cause, or to remove it once posited, and indeed precisely for this end, lest such an effect follow: For where there is no law, neither is there prevarication (Rom. 4:15), nor does he sin who uses his right.

If therefore a law, although it exists, has not yet begun to urge, for example, if someone, for the sake of recreation alone, already on Wednesday undertakes a long journey, then certainly the evil effect (omission of Mass), arising from this, cannot be imputed to him. Cf. Lehmkuhl, Cas. Consc., I, n. 97.

But here a great question arises: When ought the effect to have been impeded? when is the agent bound to omit the cause, lest a depraved effect follow from it? Resp. He is bound whenever not all the conditions are present which make the positing of the cause lawful. But what these conditions are, the following principle will indicate.

315. II. It is lawful to posit an honest cause from which there immediately follows a double effect, one good, the other evil; provided that only the good is intended by the agent, and there is present a proportionately grave cause for permitting the evil effect. The reason is because, when a proportionately grave cause accedes, the law ceases by force of which that evil effect had to be guarded against. For fear of grave harm excuses from law (n. 223). But when the law ceases, nothing now stands in the way of the effect being permitted. Cf. St. Alph., III, 483; ed. G., I, p. 702; St. Thom., 2.2, q. 64, a. 7.

The conditions which therefore are required from this second principle are precisely four, namely:

It is required 1. That the cause which is posited, or once posited is not removed, be honest, that is, good, or at least indifferent, that is, not intrinsically evil, and therefore already in itself and independently from every effect illicit, as a lie, adultery, etc., would be. Hence a girl sins gravely who fornicates in order to avoid death.

2. That the good effect follow immediately from the cause, just as the evil; for, if it followed mediately, namely with the evil effect intervening, this evil effect would now obtain the nature of a cause with respect to the good effect: which the Apostle forbids by the words already cited, saying: Let us not do evils, that goods may come (Rom. 3:8).

Hence it is not lawful for a servant to write amorous letters, so that he may please his master.

3. That the evil effect not be intended, nor approved, but merely permitted. Whence it is necessary that there not be present a danger either of intending the depraved effect, when its cause is posited, or of consenting to it, when afterwards it is produced.

Thus a physician who treats women, a student of theology who studies matters little chaste, a confessor who hears sins against chastity, are bound both to remove a dishonest end and to guard against consent in base movements, if perhaps they arise from their action.

4. That the effect not be permitted except from a proportionately grave or sufficient reason; because the natural law by which we are bound to guard against an evil effect ceases only then, when, the nature of things having been weighed and the order of precepts inspected, a cause is had properly excusing, or just and sufficient for permitting the effect. Now, in order that someone may be able, in view of a good effect, to permit an evil, the greater is the excusing cause required, the worse the effect is, or the closer to the act, or also the more probable (Konings, Theol. mor., n. 8).

a) Worse. Hence one must see what the gravity of the evil effect is. For, for example, a reason sufficient for permitting slight harm to another will not be sufficient that someone expose himself to the danger of killing another.

But for weighing this gravity, it will often be useful to attend to what law the evil effect must be guarded against by, whether by the law of charity, or of religion, or of justice? For not all laws oblige with the same rigor. Thus a cause sufficient

for excusing from a common obligation perhaps is not sufficient for excusing from a special obligation which someone has from office.

b) Closer to the act. Hence one must see whether the cause influences the effect proximately or remotely. If it influences the evil effect just as proximately as the good, the good effect ought to compensate the evil, because otherwise the good effect would not cancel the evil.

Whence a physician can treat women, although he feels base movements (provided that he does not consent to them), because the good effect, or the restoration of health, compensates the evil. But if it influences the evil effect only remotely, a lesser necessity or utility is required than in the preceding case. Hence you are not bound to abstain from an honest and useful conversation with a person of the other sex on account of carnal movements perhaps arising from it.

c) More probable. Whence one must consider whether the cause influences the depraved effect per se or per accidens. If per se, the effect will be more probable, because a cause per se is one which by its nature is ordered to the effect. If per accidens, the various circumstances which make the effect more or less probable must be weighed (Billuart, Diss. I, a. 1).

Note. 1. What effect, namely good or evil, some cause is naturally apt to produce, and what kind its influence is, must be judged from the estimation of prudent men. Many cases will be discussed in their own places, especially where the discourse is on cooperation, on scandal, on justice, on the sixth, etc., where also the studious reader will be able to see various examples of the indirect voluntary. Cf. n. 515, 521, etc.

2. The question concerning the imputability of effects which are voluntary in the cause has been weighed here only in a general way; below (n. 322) it will be said when this imputability begins, and how it ought to be judged.

II. From the doctrine concerning human acts we know that it is licit to place a cause which produces at the same time a good effect and an evil effect, if four conditions are present:

1. if the action in itself, that is, circumstances set aside, is not evil, but honorable or at least indifferent;

2. if the good effect follows from the cause at least as immediately as the evil one, or does not follow by means of the evil; otherwise it would be to work or effect good through evil, and therefore to will evil in some way as a means to good, although evils are not to be done that goods may come about;

3. if the evil effect is not intended, but only the good one; otherwise the evil effect would be voluntary in itself, or at least willed;

4. if there is a reason for placing the cause, and indeed a proportionately grave one, that is, so that the good procured exceeds or equals, and thus compensates for, the evil.

On the contrary, it is illicit if the action is evil in itself or has only an immediate evil effect, even if further from it there is procured, and intended by the agent, a much greater good effect. For although in judging the morality of the interior act of the will, it is necessary above all to regard the intention, nevertheless in judging the morality of the exterior act, one must consider not so much where it is ultimately terminated or what is intended by the agent, but first of all what is immediately done; and if that is evil, or if it immediately produces only an evil effect, even if further it tends or is ordered to some greatest good, it will always remain intrinsically evil.

The indirect voluntary or voluntary in cause, as has been said, is not intended in itself but in another thing directly willed, and from that, as an effect from a cause, is discerned as about to follow. Nevertheless it can be a true object of the will, although indirect; for he who wills the cause also wills the effect proceeding from it, if he foresees this effect and the other conditions have place. Hence the saying: he who is the cause of the cause is the cause of the caused thing. Therefore this voluntary is not always imputed unto sin; but that you may know when it ought to be imputed, attend to the two following principles.

A bad effect is then only imputed to the fault of the agent or of the one positing the cause, when the three following conditions are verified: 1st, that the agent foresaw the effect at least confusedly; 2nd, that he was able not to posit the cause; 3rd, that he is bound not to posit the cause, or to remove it once posited. For foresight at least confusedly is required, because an effect in no way foreseen and, as St. Thomas says, thought beforehand, can in no way be voluntary. It is further required that the cause could have been not posited, because liberty is the foundation of imputability, and a sin which cannot be avoided is repugnant. Finally there is required the obligation of impeding the cause, because no one is bound to remove a cause when he has the right of positing it, a right founded in necessity, utility, or honesty. Hence he is free from all fault who, while for his own or others' utility he studies matters of the sixth precept of the Decalogue, foresees that he will suffer base movements, or even pollution, and afterward in fact suffers them. Observe carefully, however, that sometimes there is no right to posit the cause; indeed there is a strict law against positing it; nevertheless the bad effect foreseen and afterward following is not imputed unto fault, because that law is not about avoiding the cause in order to such an effect. Wherefore he who eats meats on Friday with foresight of pollution indeed breaks the ecclesiastical law, but the pollution is not imputed to him. From this it is understood that for this voluntary not just any precept is sufficient, one which is as it were extrinsic and by accident by reason of such an operation, but that there must be a precept by which someone is bound to avoid lest from it another effect should follow, because a precept of this sort is what makes a moral change in the object, and not just any other precept. Cf. St. Alphonsus, nn. 10 and 14; and on the sixth precept of the Decalogue, nn. 483 and 484. - Voit, n. 6. - Baller., note (a), p. 396, vol. 1. - Suarez, De Vol. et Invol., disp. 1, sect. 4, nn. 22, 11.

It is lawful to posit a good or indifferent cause from which there immediately follows a double effect, one good, but the other bad, if there is present a proportionately grave reason, and the end of the agent is honest. The reason for the principle is that this cannot be illicit, 1st, by reason of the end, for this is supposed to be honest, and the bad effect which is foreseen as about to follow is not intended, but merely permitted; nor, 2nd, by reason of the cause, because this ought to be good, or at least indifferent; or even if it is bad, it is required that it not be bad on account of that effect about to follow, because then indeed the malice of the cause would be contracted, but not the malice of the effect. Besides, in order that the principle be true, beyond the two conditions just recounted, which regard the end and the cause, two others must be present.

Therefore it is required, 3rd, that the good effect follow at least equally immediately from the cause. The reason is that if the cause directly and immediately has an evil effect, and only by means of that does the good effect proceed, then good is sought from evil; but now it is never lawful to perpetrate evil, however slight, for procuring any good whatsoever; for according to the well-known axiom taken from the Apostle, Rom. iii, 8, evils are not to be done that goods may come.

It is required, 4th, that there be present a proportionately grave reason for positing the cause; because natural equity obliges us to avoid evils and to guard against damages to our neighbor, when we can do this without proportionately grave damage. But this damage is to be weighed not solely from the inconvenience which the agent would then suffer, but also, and much more, from the common inconvenience of all if this were generally required. I said a proportionately grave reason; for this ought to be the graver, the nearer the connection is between cause and effect, the greater is the malice of the latter, and the less right is had to the action considered in itself. Cf. St. Thomas, 2-2, q. 64, art. 7. - St. Alphonsus, on the sixth precept of the Decalogue, nn. 483 and 484.

Thus, it is lawful for someone who by horse flees an enemy and death at the same time to continue his riding when, in a narrow part of the way, there is in his path a child whom the horse will kill. Certainly that riding, through itself and from the intention of the agent, is not ordered to killing the child but to saving his own life by fleeing through that way; he enjoys a right to this safety, and indeed to obtaining it by riding: it is by accident that the death of the child follows, which he chooses neither as end nor as means; he wills it not directly but indirectly, that is, he wills this swift riding not on account of the connection which it has with the death of the child, but on account of the connection which it has with his own safety. Moreover, in these cases it is often useful to see whether the action, the bad effect being absent, would be lawful; e.g., a woman not pregnant suffers from a deadly tumor in the womb, or a man fleeing on horseback from a pursuing enemy by a narrow road in which this child is not lying; certainly the man possesses the right of fleeing so that his own death may be averted, and the woman the right to have the tumor removed by operation. Now then, it happens in the case of the one fleeing that the death of the child is induced by the riding, and in the case of the pregnant woman that the death of the fetus is induced by the operation. One and the same action has a double immediate effect: flight has safety and death, good and evil. Certainly the man has a right to the good; by this right he uses riding on account of safety; on account of this good he directly wills and posits his action. Very grave is the cause of positing that action whether the bad effect is present or absent; and the presence of that bad effect does not take away his right to posit the action on account of the good effect: the death of the child does not take away from him the right to flee his own death and to save his life; or, he is not bound to die, by omitting an action licit in itself, so that the child may not die. And the same is to be said, by equal reason, of the pregnant woman who suffers from that tumor. In both cases the agent directly wills the good effect and permits the bad; the good effect is directly intended, the bad is permitted, and each is equally immediate. Cf. De Lugo, De Jus. et Jur., disp. 10, sect. 5, nn. 123 seq.

You Will Resolve. 1st. Blasphemies, impurities, quarrels, or injustices which are done in drunkenness are voluntary in cause and imputable unto sin, when they can be foreseen and in fact are foreseen; but they are sufficiently foreseen from the custom of doing such things in this state.

2nd. A leader in war does not sin who, in time of siege, to ward off the enemy sets fields on fire, etc., even if by accident innocent inhabitants suffer. Likewise if he sets fire to a tower in which, together with enemies, perhaps pilgrims foreign to the war are enclosed; because the cause of this damage is honest in itself, but the damage of the innocent follows merely by accident, and is not intended, but only permitted.

3rd. A girl who, pregnant from a crime, procures abortion in order to avoid infamy sins gravely; because she directly intends abortion as the means by which she may free herself from infamy, and therefore seeks good from evil.

4th. If a cause remotely and lightly flows into a bad effect, and from it there also follows some good effect, although it would not preponderate or would not be equivalent to the evil, there is no obligation of removing the cause; because a lesser reason is required for positing a cause only lightly and remotely flowing into evil than if it flowed gravely and proximately. Hence you are not bound to abstain from an honest and useful conversation on account of carnal movements arising from it.

5th. But if the cause, remotely and lightly influencing, is in itself venially bad, or if no good effect follows from it, there will be an obligation of removing it, but a slight one and under venial sin only, unless there is question of grave damage to the neighbor; the reason is that this obligation is to be estimated according to the quantity of the influence of the cause. For since the effect is not voluntary except in the cause, and is contained lightly and remotely in the cause, it is lightly voluntary in it, and therefore lightly imputable unto fault; and for that reason there is present a slight obligation of removing the cause on account of that effect.

6th. The omission of acts about which a man in no way thinks is in itself and directly in no way voluntary; because those acts are impossible, since they wholly escape the advertence of the agent. Nevertheless such an omission can be voluntary and imputable in cause, if forgetfulness or inadvertence proceeds from preceding negligence.

7th. He who knowingly posits the cause of an action or omission, at that instant contracts malice before God, even if the action or omission does not in reality follow; and therefore he is bound to confess it as willed.

On the same principles concerning the indirect voluntary and the voluntary in cause depend innumerable other resolutions, especially where there will be discussion concerning scandal, and where concerning cooperation either toward another's sin, or unto the damage of one's neighbor.

Certain more recent authors reject the principle of a double effect on the ground that it contains a begging of the question; for the first condition which the said principle establishes for the lawfulness of an action requires that the cause be good or at least indifferent; secondly, because it requires that the bad effect not be intended, although intention cannot change the nature of the external action and it is permissible to intend the killing of an unjust aggressor, to which example St. Thomas applies this principle; in this example the third condition also is lacking, namely, that the good effect not follow from the bad effect; finally, the fourth condition, namely, that there be a proportionate cause, is indeed true, but according to them it is useless in practice and incapable of application.¹ Hence it is asked:

1 Ita fere Dr. W. McDonald, The Principles of Moral Science, p. 149.

1. What is the principle of a double effect, and for what does it serve?

2. Is the said principle true?

3. What is to be said about the objections recited?

1. What is the principle of the double effect, and of what use is it?

The first part of this question may be answered in the words of Dr. McDonald’s own rendering of Lehmkuhl: “It is lawful to perform an action which produces two effects, one good, the other bad, provided (1) the action, viewed in itself, is good or at least indifferent; (2) the agent does not intend the evil effect, but only the good (it is well to add in some cases, and provided there is no danger of subsequent evil consent or intention); (3) the good effect is produced as immediately as — that is, not by means of — the bad; (4) and there is a sufficiently weighty reason for permitting the evil effect.”

The use of this principle often enables us to decide whether we are bound to abstain from some action because of its producing evil effects. If the action in question has nothing but evil effects, then of course it is itself wrong. But sometimes an action has both evil and good effects. Thus if I dig a well in my own land, I may obtain a supply of water, but this good effect may be accompanied by serious loss to my neighbor if my well dries up his water-supply. The question frequently arises whether or not the evil effect (in this example loss caused to my neighbor) makes the action (digging the well) wrong. The principle enunciated above lays down the conditions under which the action in question may be done, in spite of its producing evil effects.

2. Is the principle true?

Yes; it has the support of St. Thomas (I–II, question 64, article 7) and of most recent moralists. It may be proved also from the fact that when the conditions laid down are fulfilled, there is nothing wrong either in the object or in the circumstances of the action in question, and so it may be done, for we may do anything that has nothing wrong in it. The fact that the evil effect follows does not under the supposed conditions make the action wrong; we exercise our right, and regret that this can not be done without some evil consequences which we do not desire, but only permit.

3. What is to be said about the objections mentioned in the case?

The first condition laid down in the principle is that the action viewed in itself must not be bad; but, says the objection, is not this the whole question at issue? No, it is not; there is no begging of the question in the principle. The morality of digging the well when it causes damage to my neighbor is in question, and the principle requires that this action of digging the well apart from the evil effect of causing damage to my neighbor should not be wrong in itself. If without the leave of the owner I proceed to dig a well in the property of my neighbor, the action in itself would be wrong; its malice would be at once apparent, it does not fulfil the first condition. But I have a right to dig a well in my own property, and so the first condition is fulfilled in the given example.

The second objection is that the question of intention does not arise, inasmuch as the intention can not change the nature of the external act. It is true that the intention can not change the physical nature of the external act, but it can change its moral quality. If I dig the well in my property to spite my neighbor and to deprive him of his water-supply, I commit a sin against charity, though the uncharitable intention does not change the physical nature of the external action so as to cause it to be against justice. The question of intention is therefore of importance. We need not here enter into the disputed question as to whether in self-defence one may intend to kill an unjust aggressor, or whether the intention should be exclusively directed to self-defence.

The third objection is that in killing an unjust aggressor in self-defence, to which St. Thomas applies the principle of the double effect, the good effect (the preservation of one’s own life) follows from the evil effect (the killing of the aggressor). In reply it may be said that even if this be conceded, it would only follow that the principle is wrongly applied to this case; it would not follow that the principle is false or useless. But according to the mind of St. Thomas the killing of the aggressor does not follow from the act of self-defence, but both killing and self-defence follow immediately from the blow or wound inflicted. The distinction is subtle and not of great practical importance.

The fourth condition, that there should be a sufficiently weighty reason, is not useless nor incapable of being applied, as the last objection asserts. For charity requires that I should not seek a trivial advantage of my own at the cost of serious loss to my neighbor. If I can very well do without a new water-supply, I may not dig a well in my property which would ruin my neighbor by depriving him of the only water-supply available to carry on his business. On the contrary, if a new supply is as necessary for me as it is for him, charity does not require that I should forego my own advantage lest I should deprive my neighbor of an equal advantage. Charity does not bind with so serious an inconvenience.

1. In a hilly country, two or three steps sometimes measure all the interval between the basins of two rivers, whose mouths are miles apart. In the crisis of an illness the merest trifle will turn the scale between death and recovery. In a nice point of law and intricate procedure, the lawyer is aware that scarcely more than the thickness of the paper on which he writes lies between the case going for his client or for the opposite party. To rail at these fine technicalities argues a lay mind, unprofessional and undiscerning. Hair-splitting, so far as it is a term of real reproach, means splitting the wrong hairs. The expert in any profession knows what things to divide and distinguish finely, and what things to take in the gross. Moral Science in many respects gives its demonstrations, and can give them, only "in the way of rough drawing," as Aristotle says. ([Greek: pachulos kai tupo], Ethics, I., iii., 4.) But there are lines of division exceeding fine and nice in natural morality no less than in positive law. The student must not take scandal at the fine lines and subtle distinctions that we shall be obliged to draw in marking off lawful from unlawful action touching human life.

2. It is never lawful directly to kill an innocent man. Understand innocent in the social and political sense, of a man who has not, by any human act (Ethics, c. i., n. 2, p. 1) of his own, done any harm to society so grievous as to compare with loss of life. To kill, or work any other effect, directly, is to bring about that death, or other effect, willing the same, either as an end desirable in itself, as when a man slays his enemy, whose death of its own sheer sake is to him a satisfaction and a joy, or as a means to an end, as Richard III. murdered his nephews to open his own way to the throne. We must then in no case compass the death of the innocent, either intending it as an end, or choosing it as a means. The assertion is proved by these considerations. To kill a man is to destroy the human nature within him: for, though the soul survives, he is man no more when he is dead. Now to destroy a thing is to subordinate that thing entirely to your self and your own purposes: for that individual thing can never serve any other purpose, once it is destroyed. The man that is killed is then subordinated to the slayer, wholly given up, and as we say, sacrificed, to the aims and purposes of him who slays him. But that ought not to be, for man is a person. Body and soul in him make one person, one personal nature, which human personality is destroyed in death. Now it is the property of a person to be what we may call autocentric, referring its own operations to itself as to a centre. Every person—and every intelligent nature is a person¹⁷—exists and acts primarily for himself. A thing is marked off from a person by the aptitude of being another's and for another. We may venture to designate it by the term heterocentric. A person therefore may destroy a thing, entirely consume and use it up for his own benefit. But he may not treat a person as a thing, and destroy that, either for any end of pleasure that he finds in destroying it, or in view of any gain or good, whereunto that destruction serves him as a means.

¹⁷ The exception apparent in the Incarnation is not relevant here.

3. In the above argumentation account has not been taken of God, to whom for His sovereign dominion all created personalities stand in the light of things, and may be destroyed at His pleasure. But account has been taken of the State, to which the individual is subordinate as a citizen, but not as a man and a person. It is permitted no more to the State than to the individual ever to destroy the innocent directly.

4. An effect is brought about indirectly, when it is neither intended as an end for its own sake, nor chosen as a means making towards an end, but attaches as a circumstance concomitant either to the end intended or to the means chosen. The case of a circumstance so attaching to the means chosen is the only case that we need consider here in speaking of indirect, concomitant, or incidental effects. The study of these incidents is of vast importance to the moralist. Most cases of practical difficulty to decide between right and wrong, arise out of them. They are best illustrated in the manner of killing. That one matter, well worked out, becomes a pattern for other matters in which they occur. (Ethics, c. iii., s. ii., p. 31.)

5. A man is killed indirectly, or incidentally, when he perishes in consequence of certain means employed towards a certain end, without his death being willed by the employer of those means, or in any way serving that agent to the furtherance of the end that he has in view. If a visitor to a quarry were standing on a piece of rock, which a quarryman had occasion to blast, and the man fired the train regardless of the visitor, the latter would be incidentally killed. Now incidental killing, even of the innocent, is not under all circumstances unlawful. Where the end in view is in the highest degree important, the means may be taken thereto, provided always that such an issue as the shedding of innocent blood be not itself the means discerned and elected as furthering the end: for no end however urgent can justify the employment of any evil means. (Ethics, c. iii., s. ii., nn. 3, 13, pp. 32, 36.) Suppose in the instance just given the quarryman saw that, unless that piece of rock where the visitor stood were blown up instantly, a catastrophe would happen elsewhere, which would be the death of many men, and there were no time to warn the visitor to clear off, who could blame him if he applied the explosive? The means of averting the catastrophe would be, not that visitor's death, but the blowing up of the rock. The presence or absence of the visitor, his death or escape, is all one to the end intended: it has no bearing thereon at all.

6. We must then distinguish between means and circumstances. The means help to the end, the circumstances of the means do not. When the end is of extreme urgency, circumstances may be disregarded: the means become morally divested of them. So I have seen an island in a river, a nucleus of rock with an environment of alluvial soil. While the stream was flowing placidly in its usual course, the island remained intact, both rock and earth. But when the water came rushing in a flood, which was as though the island itself had gone speeding up the river, the loose matter at its sides was carried away, and only the central rock remained. The ordinary flow of the river past the island, or the gentle motion of the island up-stream, keeping all its bulk, represents a man acting for an end to which reason attaches no great importance. He must then take a diligent review of all the circumstances that have any close connection with his action, to see if there is any that it would be wrong for him to will directly. And if there is, he must abstain from willing it even indirectly: that is, he must abstain from doing the action, which cannot be done without that objectionable circumstance attending it. On the other hand, the floating island being towed rapidly up-stream, with its loose sides falling away, portrays the condition of one acting for a purpose of imperative urgency: he considers the means to that end, and if they are good, he concentrates his will upon them and uses them, disregarding, or even deploring, but nowise willing or being responsible for, the evil concomitants which go with those means, but do not make for his end. Thus it is, that a circumstance which in ordinary cases goes to make the adoption of certain means reasonable or unreasonable, comes, in a case of great urgency, to weigh for nothing in the balance of reason, owing to the extreme and crying reasonableness of the end in view. Nor is this the end justifying the means, for that unhappy circumstance is never a means to the end. (Ethics, c. iii., s. ii., n. 8, p. 34.)

7. To illustrate by a diagram:

[Illustration:

C
( )
U
|
|
A—————————————————-E( )V
]

A, the agent, a bead on a wire, can move only on the line AE, that alone being the line of means to the end.

EV, reasonableness of end in view, attracting A.

UC, the amount of moral evil which the untoward circumstance would involve, if it were willed directly. This UC repels A, tending to jam it on the line AE, which is absolutely rigid.

AE, remoteness, difficulty, and uncertainty of the end in view.

AU, remoteness of untoward circumstance from means chosen, which A is just in the act of taking. Then, for lawful action, the reasonableness required in the end in view is represented by the variation—

[Illustration:
UC . AE
EV varies ———-
AU
]

We observe that when AU is zero, while UC . AE remains a finite quantity (representing an appreciable evil), then EV becomes infinite: that is to say, when the distance, difference, or distinction between the evil circumstance and the means comes down to nothing at all, and the evil thing actually is the very means taken, then an infinite urgency of end in view would be requisite to justify the using of that means: in other words, no end possible to man can ever justify an evil means.

Readings.—St. Thos., 2a 2æ, q.64, art. 6; Cardinal de Lugo, De Justitia et Jure, disp. 10, n. 125.

1. On the question, whether it is lawful for one man to kill another in self-defence, St. Thomas writes (2a 2æ, q. 64, art. 7):

"There is nothing to hinder one act having two effects, of which one only is within the intention [and election] of the doer, while the other is beside his intention [and election, that is, is neither intended as an end nor elected as a means]…. From the act therefore of one defending himself a twofold effect may follow, one the preservation of his own life, the other the killing of the aggressor. Now such an act, in so far as the preservation of the doer's own life is intended, has no taint of evil about it, seeing that it is natural to everything to preserve itself in being as much as it can. Nevertheless, an act coming of a good intention may be rendered unlawful, if it be not in proportion to the end in view. And therefore, if any one uses greater violence than is necessary for the defence of his life, it will be unlawful. But if he repels the violence in a moderate way, it will be a lawful defence: for according to the Civil and Canon Laws it is allowable to repel force by force with the moderation of a blameless defence. Nor is it necessary to salvation for a man to omit the act of moderate defence in order to avoid the killing of another; because man is more bound to take thought for his own life than for the life of his neighbour. But because to kill a man is not allowable except by act of public authority for the common good, it is unlawful for a man to intend [that is, elect and choose as a means] to kill another man in order to defend himself, unless he be one who has public authority, who intending [electing] to kill a man in order to his own defence, refers this to the public good."

2. The right then of self-defence even to the shedding of blood involves a mere exercise of indirect killing for a proportionably grave cause. The cause in question is the defence of your own life, or your friend's, or of some other good or possession that can weigh with life, as the honour and inviolability of your person, or a large sum of money. This must be in present danger of being taken away otherwise than in due course of justice. The danger must be present, and even imminent, not prospective. The right of self-defence even to the grievous harming of the aggressor, endures only while the danger from him is imminent, not when it is past, or the evil is already done. The right supposes no moral obliquity, no formal injustice on the part of the aggressor: he may be a madman making for you with a drawn sword. Nay further, not even material injustice—that is, the quality of an act which would be formally unjust, if only the agent knew what he was about—is required. All that is requisite is that your life, or something equivalent to life, be threatened, not in due course of law.

3. The essential idea of self-defence is that of stopping a trespasser, one who, however innocently, is going about to trench on that good which you have a right to maintain and reserve to yourself. It is then no act of authority that you perform, but the dealing of one private person with another. Indeed, the party stopped is hardly regarded as a person: no account is taken of his demerits: he is regarded simply as an abridger and diminisher of what you have a right to preserve intact. You stop a man as you stop a horse, only with more regard to the moderation of a blameless self-defence, not using more violence than is necessary here and now to preserve what you have to preserve.

4. The stopping, unfortunately, has often to be done in a hurry: there is no time to wait: for the next moment, unless you act promptly, it will be all too late, or all to no purpose, to act at all. Being done in a hurry, it has to be done in a rough-and-ready way, with such instruments as are to hand: you cannot afford to be nice about the means, carefully purifying them, and shaking off the dust of objectionable circumstances. Now to stop a man in mid career all on a sudden, to render him powerless where he was about to strike, motionless in the direction whither he was about to go, and that in an instant, is of common necessity a rude treatment, very dangerous to him who experiences it, and under some conceivable circumstances hopelessly fatal. Still the fatality—in plain words, the death of the aggressor—is not directly willed. It is neither intended as an end, nor chosen as a means to an end. It is not welcomed as an end and desirable consummation: on the contrary, it is put up with most reluctantly as coming from your act: for you, a private individual, have no right to will and effect the death of any man, however guilty, as will be proved hereafter. It is not chosen as a means: for, formally as his death, it is no means to your end, which was the averting of all present danger to your right. For that it was enough to stop the trespasser; and you chose the means as a stopping means, not as a killing means. True, in stopping him you killed him, but you did not kill him to stop him. You struck him to stop him: that your blow was a mortal blow, was a circumstance which you did not choose and could not help. All killing then in self-defence is indirect.

5. By this explanation, resting on St. Thomas—in opposition to Cardinal de Lugo (De Just. et Jure. 10, 149) and others, who allow killing in self-defence to be the actual means chosen, and therefore directly willed—we save four grand positions in Moral Science:

(a) The axiom, that it is never lawful directly to take the life of an innocent man. For the person who perishes by occasion of your defending yourself, may be innocent formally, and even materially also.

(b) Likewise the axiom, that it is never lawful for a private individual to kill any one whatever. We say, from a technical standpoint, that he does not kill but arrests the onset of the aggressor.

(c) We are in hearty accord with the positive law of all civilized countries, which views with extreme suspicion all deaths said to be done in self-defence, the law being jealous of the blood of its citizens, and reserving the shedding thereof to itself. We teach that only by process of law can a man ever be directly slain, his death made a means of, and the person, who strikes him, really willing and seeking, exactly speaking, to kill him.

(d) The initial error is revealed of a theory that we shall have to combat at length hereafter, the theory of Hobbes and Locke, that the power of the State is the mere agglomeration of the powers of the individuals who compose it. It appears by our explanation that the individual has no power strictly to take life in any case, or ever to kill directly, as the State does when it executes a criminal.

As a fifth point gained, we may mention the efficacious argument afforded, as will presently be shown, against the acceptance of a duel under any conceivable circumstances, a thesis otherwise not easy to establish by reason.

6. In view of the question of the origin of civil government, we must carefully collect the differences between self-defence and punishment. Death occasioned in self-defence is indirect: death inflicted as punishment is direct. Punishment is an act of authority, of distributive justice, which lies from ruler to subject (Ethics, c. v., s. ix., n. 4, p. 104): self-defence is of equal against equal. Punishment is medicinal to him who suffers it, or deterrent on behalf of the community, or retributive in the way of vengeance. (Ethics, c. ix., s. iii., n. 4.) Self-defence is not on behalf of the community, still less for the good of the aggressor, but for the good of him who practises it and for the preservation of his right: neither is it retributive and retrospective, as vengeance is, but simply prospective and preventive of a harm immediately imminent. Finally, the right to punish abides day and night: but the right of self-defence holds only while instant aggression is threatened.

7. These two diverse ideas of self-defence and vengeance were confounded by the Greeks under the one verb [Greek: amunesthai]. They are confounded by Mill, On Utility, in the fifth chapter where he speaks (p. 77) of the "instinct of self-defence," which nine lines below he converts into "the natural feeling of retaliation or vengeance." It is a common but a grave mistake, and the parent of much bad philosophy.

Reading.—St. Thos., 2a 2æ, q. 64, art. 7.