A. 8. Is One Who Accidentally Kills Another Guilty of Homicide?
[This question is divided into eight articles, three of which are translated here.]
We thus proceed to the sixth inquiry. It seems that it is sometimes lawful to kill an innocent person, for the following reasons:
Obj. 1. Sin does not manifest fear of God. On the contrary, “fear of the Lord drives away sin,” as Sir. 1:27 says. But Abraham is praised for having feared God, since he was willing to kill his innocent son.1 Therefore, one may without sin kill an innocent person.
Obj. 2. Of sins committed against neighbor, the more serious the harm inflicted on the person against whom one sins, the more serious seems to be the sin. But killing a sinner harms the sinner more than killing an innocent person harms the innocent person, who by death goes from the wretchedness of this life to heavenly glory. Therefore, since it is sometimes lawful to kill a sinner, much more is it lawful to kill an innocent or righteous person.
Obj. 3. Things done in accord with the order of justice are not sins. But the order of justice sometimes compels one to kill an innocent person. For example, judges, who are bound to judge according to the evidence, condemn to death those accused by false witnesses, although the judges know the accused to be innocent. And the same is true about an executioner who, obeying a judge, kills an unjustly condemned man. Therefore, one may without sin kill an innocent person.
On the contrary, Ex. 23:7 says: “You shall not kill any innocent or righteous person.”
I answer that we can consider an individual human being in two ways: in one way as such; in a second way in relation to something else. Considering human beings as such, it is indeed never lawful to kill {168} anyone, since, in the case of every human being, even a sinner, we should love the nature that God created, and that killing destroys. But as I have said before,2 killing sinners becomes lawful in relation to the common good, which sin corrupts. On the other hand, the life of the just preserves and promotes the common good, since the just are the most important members of the community. And so it is never lawful to kill an innocent person.
Reply Obj. 1. God has dominion over life and death, since both sinners and the righteous die by his ordinance. And so a person who kills an innocent at God’s command does not sin, just as God, whose will such a person carries out, does not. And such a person in obeying God’s commands manifests fear of him.
Reply Obj. 2. In weighing the seriousness of sin, we should consider the intrinsic rather than the accidental. And so one who kills a righteous person commits a more serious sin than one who kills a sinner. First, this is indeed so because those who kill a righteous person harm one whom they should love more, and so act more against charity. Second, it is so because they inflict injury on one who less deserves to be injured, and so act more against justice. Third, it is so because they deprive the community of a greater good. Fourth, it is so because they thereby contemn God more, as Lk. 10:16 says: “Those who despise you, despise me [Christ].” But it is incidental to killing that God brings a righteous person to glory.
Reply Obj. 3. If a judge knows that one accused by false witnesses is innocent, the judge should examine the witnesses more closely in order to find a way to acquit the innocent person, as the prophet Daniel did.3 But if the judge cannot acquit the person, the judge should remit the person to a higher court. And if the judge cannot do this, the judge does not sin in passing judgment according to the evidence, since those who accused the innocent person, not the judge, kill the accused.
And the official assigned to carry out a judge’s order to execute an innocent person should not obey the order if the sentence contains flagrant error. Otherwise, the executioners who killed the martyrs would be excused of moral fault. But if the sentence contains no evident injustice, the official does not sin in carrying out the order, since the official has no right to dispute the judgment of a superior. Nor does the official kill the innocent person. Rather, the judge, whom the official serves, does so.
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We thus proceed to the seventh inquiry. It seems that it is not lawful for anyone to kill another in self-defense, for the following reasons:
Obj. 1. Augustine says in a letter to Publicola: “I do not agree with the advice that one may kill another lest one be killed by the other, except perhaps in the case of a soldier or public official, who is legally authorized and does so for the sake of others and not to save himself, provided that the person slain deserves to be.”4 But one who kills another in self-defense does so lest the other kill oneself. Therefore, this seems to be unlawful.
Obj. 2. Augustine says in his work On Free Choice: “How in the sight of divine providence are they free of sin who are stained with human slaughter for the sake of such contemptible things?”5 But he calls things contemptible “that human beings can lose against their will,” as is evident from what he said immediately before.6 And corporeal life is one of these things. Therefore, it is unlawful for anyone to kill a human being to save one’s corporeal life.
Obj. 3. Pope Nicholas I says,7 and the Decretum maintains8: “You inquire regarding the clerics about whom you consulted us, namely, those who killed a pagan in self-defense, whether they could after repentance later return to their former station or rise to a higher station. Know that we admit no occasion nor grant any permission to them to kill any human being under any circumstance.” But clerics and laypersons alike are obliged to observe moral precepts. Therefore, it is also unlawful for laypersons to kill anyone in self-defense.
Obj. 4. Homicide is a more serious sin than adultery or ordinary fornication. But it is unlawful for anyone to commit adultery or ordinary fornication or any other mortal sin to save one’s life, since one should prefer one’s spiritual life to one’s corporeal life. Therefore, it is unlawful for anyone to kill another in self-defense in order to save one’s life.
Obj. 5. If a tree is rotten, so is its fruit, as Mt. 7:17–8 says. But self-defense itself seems to be unlawful, as Rom. 12:19 says: “Do not defend yourselves, dearly beloved.” Therefore, killing a human being in self-defense is unlawful.
On the contrary, Ex. 22:2 says: “If a thief should break into or dig under one’s home and be wounded and die, the defender who inflicted the wound will not be guilty of the thief ’s blood.” But it is much more lawful {170} to defend one’s life than to defend one’s home. Therefore, neither is one who should kill another in self-defense guilty of murder.
I answer that nothing prevents one action having two effects, only one of which is intended, and the other of which is unintended. But as is clear from what I have said before,9 what one intends specifies moral actions, not what one does not intend, since the latter result is incidental. Therefore, one’s action in defending oneself can have two effects: saving one’s life and slaying the aggressor. And so such acts of self-defense, as one intends by them to preserve one’s life, do not have the character of being unlawful, since it is natural for everything to keep itself in existence as far as possible.
But an action originating from a good intention can be rendered unlawful if the action should be disproportionate to the end. And so it will be unlawful to use greater force than necessary to defend one’s life. And it will be lawful in self-defense to resist force in due moderation, since the laws “permit one to resist force with force in the measure of blameless self-defense.”10 Nor is it necessary for salvation that human beings omit acts of moderate self-defense in order to avoid killing another, since they have a higher obligation to safeguard their own lives than the life of another.
Nonetheless, it is only lawful for public authority to kill human beings, and in that case only for the common good, as is evident from what I have said before.11 Therefore, it is unlawful for human beings other than those holding public authority to intend to kill an aggressor in the course of self-defense. And those holding public authority, intending to kill human beings in the course of self-defense, relate such killing to the public good. The latter is evident in the case of soldiers warring against enemies and in the case of police fighting against robbers, although even these sin if they are motivated by private animosity.
Reply Obj. 1. We should understand the cited authority of Augustine to apply to the case of one who intends to kill another in order to avoid death.
Reply Obj. 2. And we should also understand the cited authority of Augustine quoted from his work On Free Choice to apply to such a case. And so he significantly adds “for the sake of these things,” meaning “with such an intention.” And this makes clear the reply to the second objection.
Reply Obj. 3. Acts of homicide, even if they be without sin, as in the case of judges who justly condemn persons to death, result in clerics {171} incurring the canonical penalty of irregularity. And so clerics, even if they kill someone in self-defense, incur irregularity, although they intended only to defend themselves, not to kill.
Reply Obj. 4. Acts of fornication or adultery are not necessarily ordered to saving one’s life, as are acts that sometimes result in homicide.
Reply Obj. 5. The cited text forbids self-defense that is vengeful. And so a gloss says: “Do not defend yourselves, that is, do not strike back against your enemy.”12
We thus proceed to the eighth inquiry. It seems that one who accidentally kills another is guilty of homicide, for the following reasons:
Obj. 1. We read in Gen. 4:23–4 that Lamech, thinking he was killing a wild beast, killed a human being, and he was considered guilty of homicide. Therefore, those who kill another accidentally incur the guilt of homicide.
Obj. 2. Ex. 21:22–3 says: “If one should strike a pregnant woman and cause a miscarriage, if her death should result, will repay life for life.” But this can happen without the one who strikes the woman intending to kill her. Therefore, accidental homicide incurs the guilt of homicide.
Obj. 3. The Decretum contains several canons that prescribe penalties for accidental homicides.13 But only sins deserve punishment. Therefore, those who kill another accidentally incur the sin of homicide.
On the contrary, Augustine says in a letter to Publicola: “Let not things that we do for a good and lawful purpose be imputed to us if anything evil thereby happens to another unintentionally.”14 But homicide may sometimes accidentally happen as a result of people doing things for good purposes. Therefore, such accidental homicides should not be imputed as sins.
I answer that, as the Philosopher says in the Physics,15 chance is a cause that produces an effect unintentionally. And so accidental things are, strictly speaking, neither intended nor voluntary. And because every sin is voluntary, as Augustine says,16 it follows logically that accidental things as such are not sins. But what is not actually willed or intended may be willed and intended incidentally, insofar as we call accidental a cause that {172} removes something that prevents an effect. And so those who do not remove things that result in homicide, if they should remove them, will be guilty of voluntary homicide in one respect.
And the latter may happen in two ways. It may happen in one way if one causes homicide in the course of unlawful activity, which one ought to avoid. It may happen in a second way if one does not take proper care. And so, according to the laws,17 if a person be engaged in lawful activity and exercise proper care, and homicide thereby result, the person is not guilty of homicide. But if a person is engaged in unlawful activity or engaged in lawful activity without exercising proper care, the person does not escape the guilt of homicide if one’s activity should result in the death of a human being.
Reply Obj. 1. Lamech did not take sufficient care to avoid homicide. And so he did not escape the guilt of homicide.
Reply Obj. 2. Those who strike a pregnant woman act unlawfully. And so they do not escape the guilt of homicide if either the woman or the ensouled fetus dies as a result, especially if death would clearly result from such a blow.
Reply Obj. 3. The canons impose penalties on those who kill accidentally when engaged in unlawful activities or not exercising proper care.
1Gen. 22:12.
2ST II–II, Q. 64, A. 2
3Dan. 13:51–9 (Septuagint).
4Letter 47, to Publicola, n. 5 (PL 33:186).
5On Free Choice I, 5, n. 13 (PL 32:1228).
6Ibid.
7Letter 138, to Osbald (PL 119:1131).
8Gratian, Decretum I, dist. 50, c. 6.
9ST I–II, Q. 72, A. 1; II–II, Q. 43, A. 3.
10Gregory IX, DecretalsV, title 12, c. 18.
11ST II–II, Q. 64, A. 3.
12Peter Lombard, Glossa, on Rom. 12:19 (PL 191:1502).
13Gratian, Decretum I, dist. 50, cc. 4–8.
14Letter 47, to Publicola, n. 5 (PL 33:187).
15Physics II, 6 (197b18–22).
16On True Religion 14, n. 27 (PL 34:133).
17Gratian, Decretum I, dist. 50, cc. 48, 49.