The Catholic Church acknowledges the possibility of legitimate defense by military force, while also setting rigorous moral conditions for its use 1. The Church recognizes the right of governments to lawful self-defense against unjust aggression to protect the common good and innocent life 2. However, it also encourages peace efforts and the development of international bodies to prevent war 2.

Here's a breakdown of the key aspects of the Church's teaching on just war:

Just War Theory

• Conditions for a Just War:

  • Just Cause: War is only justified to confront a grave evil that cannot be effectively addressed by other means 3. It should be an act of self-defense, not aggression 3.
  • Legitimate Authority: The decision to go to war must be made by a legitimate ruler or be authorized by international law 3.
  • Right Intention: Those waging war must aim to advance good and avoid evil, not for aggrandizement, cruelty, or lust for power 4. The intention must be upright, acting for the sake of the stated cause, not for strategic or economic gain 3.
  • Last Resort: War should be a last resort, pursued only after all other political, economic, and diplomatic options have been exhausted 3.
  • Probability of Success: There must be a reasonable chance of success without causing more harm than the evil being opposed 3.
  • Proportionality: The harm caused by the war must not be greater than the evil being addressed 1.
  • Legitimate Means: War must be waged using legitimate means, distinguishing between combatants and non-combatants, avoiding targeting the general population, and prohibiting weapons of mass destruction 3. Actions like killing unarmed prisoners, indiscriminate bombing, or targeting schools and hospitals are not legitimate 5.

• Moral Law in Armed Conflict: The moral law remains valid during armed conflicts, meaning not everything is permissible between warring parties simply because war has broken out 6.

• Grave Violations of Human Dignity: The Church, echoing various Popes, firmly states "never again war!" 7. It is contradictory to base war on religious convictions 7.

Contemporary Considerations

• Modern Warfare: Due to the destructive potential of modern weapons, especially nuclear, chemical, and biological ones, it is increasingly difficult to justify war 1 8. The Church acknowledges the risk that the evils and disorders resulting from modern warfare may outweigh the evil being eliminated 1.
• Prudence: It is crucial to consider whether new technologies have given war an uncontrollable destructive power over innocent civilians 1.
• Alternatives to War: The Church emphasizes the importance of preventing conflicts, resolving them peacefully, and promoting reconciliation after conflicts 9.

Importance of Peace

• Promoting Peace: Catholics are called to work to avoid war and promote peace, resisting indifference to armed conflicts 9. War indicates a failure to uphold human dignity 9.
• Defense Against Threats: Nations have the right and obligation to defend human life and the common good against terrorism, aggression, and persecution 9.
• Conscientious Objection: The Church recognizes the moral right to conscientious objection to war 9.

In summary, the Catholic Church approaches the concept of "just war" with caution, emphasizing its immense human cost and the stringent conditions that must be met to justify it morally. While acknowledging the right to self-defense, the Church prioritizes peaceful means of conflict resolution and expresses deep concern over modern warfare's potential for widespread destruction and its impact on innocent civilians.