A question regarding self defense


A recent thread (forums.catholic.com/showthread.php?t=1012490) got me thinking about self defense in the context of “the ends do not justify the means”. Now I know the Church teaches both; self-defense is ok, and the ends don’t justify the means.

My problem is that these two seem to contradict themselves. In the case of self-defense, the end is to ensure your own survival, and the means is to kill or injure the person threatening you. In that case, wouldn’t the ends justify the means? If the Church teaches that the ends do not justify the means, it would seem to contradict that self-defense is ok.

Any explanations to this question would be great. I’m sure the Church has an answer; my limited mind just isn’t capable of seeing it. Thanks!


By that logic God contradicted himself constantly in the OT… or did He?

Unauthorized killing is wrong because it is an act against God purely and simply. It seeks to remove a person fron life prior to their due time.

Killing in self defense is more like OT orders. In the absence of direct orders from God we have a set of specific situations in which to act. Self defense/defense of others seeks to stop the denying of God’s will and such.


“Moreover, “legitimate defense can be not only a right but a grave duty for someone responsible for another’s life, the common good of the family or of the State”. Unfortunately it happens that the need to render the aggressor incapable of causing harm sometimes involves taking his life. In this case, the fatal outcome is attributable to the aggressor whose action brought it about, even though he may not be morally responsible because of a lack of the use of reason.” - Pope John Paul II, Evangelium Vitae # 54-55, 1995.

“It is lawful to repel force by force, provided one does not exceed the limits of a blameless defense.” - St. Thomas Aquinas

I think St. Thomas Aquinas hits the nail on the head. You can “repel force by force” but you cannot “overdue it”. You can defend yourself (or in the defense of others) from physical harm but once the threat is neutralized, you must cease your activities.

Sometimes this “neutralization” involves taking someone’s life in self defense. As Pope John Paul II states, this outcome is attributed to the original aggressor who brought about the action and not the fault of the innocent person who was merely defending themselves.


Thanks for some answers, though my question is more along the lines of how the Church justifies self defense, while also justifying “the ends don’t justify the means”. Still, thanks, but I’m hoping you all can give me a more direct answer.


The means are stopping the unjust aggressor. If lethal force is neccessary to stop them, the death is an unintended (though unavoidable) secondary effect; stopping them is morally speaking stil the means.


Where in the Catechism do you find: “the ends don’t justify the means”?

In any case, it is clear that the use of deadly force is not always prohibited by Christian teaching.


Actually this is not a case of the end justifying the means. The purpose of defending oneself is not to cause harm to the other person, but to provide for ones safety through ceasing the activity of another trying to do you harm. It is the intention of the action in response to the current level of threat.

This could be done by removing oneself (running), calling the police, requesting help or taking personal action with a non-lethal method or a lethal method. Generally it is the lowest, or least harmful, level which is recommended / required. Physical harm to another only being justified when no other reasonable alternative exists. The case you mention would be a justifiable use of force, but not the end justifying the means.

The situation is similar in concept to an ectopic pregnancy. In dealing with the problem which is endangering the mother, the life of the baby will be ended. The purpose is not to end the life of the baby, but to save the mother. In this case, there is only one solution and a consequence will lead to the death of the child. Same in the case of self defense you mention.

An “end justifying the means” would be where one justifies say, the killing of an abortion doctor or destruction of an abortion clinic in order to save the lives of the babies who will be aborted. The Church has already spoken that the end does not justify the means in these situations.

Thanks for the topic.


CCC 1753: A good intention (for example, that of helping one’s neighbor) does not make behavior that is intrinsically disordered, such as lying and calumny, good or just. The end does not justify the means. Thus the condemnation of an innocent person cannot be justified as a legitimate means of saving the nation. On the other hand, an added bad intention (such as vainglory) makes an act evil that, in and of itself, can be good (such as almsgiving).


From the CCC:
Legitimate defense

*2263 The legitimate defense of persons and societies is not an exception to the prohibition against the murder of the innocent that constitutes intentional killing. "The act of self-defense can have a double effect: the preservation of one’s own life; and the killing of the aggressor. . . . The one is intended, the other is not."65 *

To be permitted, acts which have two moral effects – one good and one evil, the act, actor and effects must meet four conditions:
*]The act must be morally good or neutral.
*]The actor must intend the good end.
*]The good effects must be a least proportional to the evil effect or the good outweigh the evil.
*]The good effect may not proceed through the evil effect (end may not justify the means).


It would help if you didn’t short hand the moral argument.

The church teaches, one may not do evil that good may come from it.

Then there is the law of double effect. This law basically says, one may do something even if as a foreseeable consequence but not its intention evil may occur.

That is where self defense lies.

In self defense, the end is turning away an unjust aggression. One may use lethal force to turn away that aggression, but the force should always have the intent of stopping the unjust attack not killing the person.

So think of a policeman.

He arrives at a man who is fleeing a robbery with a knife. The man gets in a car and speeds off. The cops don’t shoot him because that’s not the end. They follow, do various maneuvers to stop the car, finally they succeed. The car crashes and the man gets out holding the knife. The police still don’t shoot him but order him to drop it. They pull their guns in hopes that threat forces a change of mind. The man then runs at the cops and lunges at one with the knife. Then they shoot. Their shooting should be done just enough to stop the man not kill him but they know full well when you shoot someone it’s likely they will die.

The end is stopping the attack, not killing the person.

That’s the principle of double effect.


Self-defense is an act of defending your right to live. As long as you understand the gravity of the moral seal, we can understand that you can act freely without it.


Ah, I see. Thank you all for your great answers!


Regarding point 1, note that killing in self defence - in particular, the scenario where a conscious decision is made to kill - is an evil, but it is a physical evil, distinguished from a moral evil such as murder. Just as we may break down a door (physical evil) to save a child, so other physical evils may be permissible in various human acts. Amputation as medical treatment is one, killing in self defence is another. Now these acts are not guaranteed to be good - but depend on good intentions (point 2) and optimizing the consequences (point 3).

When we say, “we may not do evil to bring about good” (point 4) it is moral evil to which we refer.


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