Ethics of War and Peace

1. Introduction

The ethics of war and peace investigates when, if ever, armed force can be justified, how it must be constrained, and what justice requires before, during, and after conflict. It lies at the intersection of moral philosophy, political theory, international law, theology, and strategic studies, and addresses practices that have shaped state formation, empire, decolonization, and contemporary global governance.

Historically, thinkers have approached war in three broad ways. Just war traditions hold that some wars can be morally warranted under strict conditions. Pacifist traditions maintain that war, or at least modern war, is morally unacceptable and that nonviolent alternatives should be pursued. Realist approaches downplay or deny the relevance of moral norms to war, treating it primarily as an instrument of power and survival. More recent cosmopolitan and revisionist views challenge state‑centred assumptions, focusing instead on individuals’ rights and responsibilities.

The field is both analytical and practical. It develops normative frameworks—such as jus ad bellum (justice in resorting to war), jus in bello (justice in the conduct of war), and jus post bellum (justice after war)—and applies them to concrete issues: humanitarian intervention, terrorism, nuclear deterrence, autonomous weapons, cyber operations, and transitional justice.

Because war implicates fundamental values—life, security, liberty, sovereignty, and human rights—debates in this area are often deeply contested. Proponents of different positions disagree not only about the permissibility of particular conflicts, but also about the basic moral vocabulary appropriate to assess them: duty versus consequence, rights versus interests, national versus global obligations.

This entry surveys how the ethics of war and peace has developed historically, outlines its main conceptual tools and theoretical camps, and presents the principal controversies that structure contemporary discussion, without endorsing any one approach.

2. Definition and Scope of the Ethics of War and Peace

The ethics of war and peace can be defined as systematic reflection on the moral norms governing the resort to, conduct of, and recovery from organized armed conflict, together with the duties to prevent war and secure just and stable peace.

Core Domains of Inquiry

Philosophers and theorists usually distinguish three interrelated domains:

Some authors broaden the scope further to include jus ante bellum (duties to create conditions of peace and reduce war risks) and jus ex bello (obligations to exit or end ongoing wars).

Boundaries of the Field

There is debate about what counts as “war” for ethical purposes. Traditional accounts focus on interstate conflict. More recent discussions also address:

• Civil wars, insurgencies, and guerrilla warfare
• Terrorism and counterterrorism operations
• Occupation, secession, and colonial or anti‑colonial conflicts
• Low‑intensity and hybrid conflicts, including cyber operations

The field overlaps with international humanitarian law and human rights law, but remains distinct in two ways. First, it asks what the law ought to be, not only what it is. Second, it evaluates actors—leaders, soldiers, rebels, and civilians—by moral standards that may exceed or differ from legal rules.

In terms of method, the ethics of war and peace incorporates deontological, consequentialist, virtue‑ethical, religious, and pragmatist perspectives, as well as empirical work from history and social science, while maintaining its focus on normative assessment rather than explanation alone.

3. The Core Moral Questions of War and Peace

Debate in war and peace ethics is organized around a series of recurring moral questions. These questions structure the application of just war theory, pacifism, realism, and revisionist approaches alike.

Questions About Resorting to War

1. Is war ever morally permissible?
   Pacifists answer negatively (or nearly so), while just war theorists allow for defensive or humanitarian wars under strict conditions, and realists often treat permissibility in moral terms as largely irrelevant.

2. What constitutes a just cause?
   Traditional candidates include self‑defense, defense of others, and rectification of grave injustice. Disagreement concerns the status of preventive war, regime change, protection of human rights abroad, and responses to terrorism.

3. Who has the authority to wage war?
   Views differ on whether only sovereign states, properly constituted governments, international organizations, or also non‑state groups (e.g., liberation movements) can legitimately initiate war.

4. When is war a last resort?
   The threshold at which negotiation, sanctions, and other measures are deemed exhausted is interpreted more restrictively or expansively by different theorists.

Questions About Conduct and Responsibility

1. Whom may combatants target?
   The principle of discrimination insists on protecting non‑combatants, yet modern warfare’s blurred lines—militias, dual‑use infrastructure, drones—complicate this.

2. What level of collateral damage is tolerable?
   Proportionality assessments balance anticipated military advantage against expected harm to civilians; critics dispute the reliability and bias of such calculations.

3. Are soldiers on opposing sides morally equal?
   The traditional idea of the moral equality of combatants is challenged by revisionists, who argue that responsibility for unjust aggression undermines such equality.

4. What are individual duties in unjust wars?
   This includes questions about conscientious objection, selective refusal, and the moral liability of political leaders versus ordinary soldiers.

Questions About Ending War and Building Peace

1. What counts as a just peace?
   Competing views emphasize punishment, deterrence, reconciliation, redistribution, or institutional reform.

2. How should blame and reparations be allocated?
   Debates center on collective versus individual responsibility, victors’ justice, and the ethics of sanctions and indemnities.

These core questions frame the historical and contemporary approaches surveyed in subsequent sections.

4. Historical Origins and Ancient Approaches

Ancient reflections on war did not usually appear as separate “war ethics,” yet they contain many of the ideas later systematized in just war theory, pacifism, and realism. They are typically embedded in broader views of virtue, cosmic order, and political community.

Greek and Roman Thought

Greek literature and philosophy portray war as both an arena of honor and a site of moral ambiguity. In Homeric epics, heroic valor coexists with depictions of suffering civilians. Thucydides, often seen as a precursor of realism, presents war as shaped by fear, honor, and interest, but also highlights rhetorical appeals to justice.

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“The strong do what they can and the weak suffer what they must.”

— Thucydides, History of the Peloponnesian War

Plato and Aristotle treat war as subordinate to the good of the polis. Plato links just war to the defense and proper ordering of the ideal city, while Aristotle distinguishes between wars of defense or liberation and those for conquest or enslavement, sometimes endorsing the latter where “natural slavery” is presumed.

Roman thinkers such as Cicero articulate early criteria for bellum iustum (just war), requiring public declaration, proper authority (the Senate or people), and wrongs suffered. War is framed as a legal and moral instrument within a law‑governed imperial order.

Ancient Asian and Indian Traditions

In China, texts attributed to Sunzi (Sun Tzu) focus on strategic and prudential constraints—winning without battle, minimizing destruction—but some interpreters discern implicit ethical limits insofar as unnecessary suffering and prolonged war are condemned as failures of wise rule.

Confucian thinkers such as Mencius distinguish between legitimate punitive expeditions and illegitimate aggression, grounding permission to wage war in benevolent governance and popular support.

In the Indian Dharmashastra corpus and epics like the Mahābhārata, warfare is regulated by detailed rules: prohibitions on attacking unarmed or fleeing enemies, protections for non‑combatants, and codes for righteous kingship. Yet these texts also express deep ambivalence about the moral costs of warfare.

Early Nonviolence and Restraint

Buddhist and Jain traditions introduce radical critiques of killing and harm. While Buddhist polities sometimes engaged in warfare, canonical texts emphasize compassion and non‑injury, influencing later pacifist currents. Jainism’s ahimsa principle condemns violence in especially stringent terms.

Ancient approaches thus provide diverse prototypes: legalistic Roman just war, Greek realist analysis, Asian strategic minimalism, and Indian and Buddhist‑Jain nonviolence, all of which inform later medieval and modern developments.

5. Medieval Just War Tradition in Christian and Islamic Thought

Medieval Christian and Islamic thinkers developed sophisticated doctrines governing when and how war may be waged, integrating scriptural teachings with philosophical reasoning and emerging legal institutions.

Christian Just War Doctrine

Building on Augustine and canon law, medieval Christian theology framed war within divine and natural law.

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“Peace should be the object of your desire; war should be waged only as a necessity.”

— Augustine, Letter 189

Augustine of Hippo argued that war can be permissible to restrain wrongdoing and secure peace, provided it is ordered by legitimate authority and motivated by charity rather than hatred. Later scholastics, especially Thomas Aquinas, systematized this view. Aquinas’s widely cited conditions for a just war are:

• Legitimate authority: Only rightful rulers may declare war.
• Just cause: Typically, to avenge a wrong or repel aggression.
• Right intention: The aim must be the advancement of good and avoidance of evil, especially peace.

Canon lawyers and church councils elaborated these ideas into legal norms about truces, protection of clergy and pilgrims, and conduct toward non‑combatants. At the same time, crusading ideology introduced a notion of “holy war,” where participation itself was seen as meritorious, creating tensions within Christian war ethics.

Islamic Jihad and Siyar

In Islamic thought, jurists in the classical period articulated rules of war and peace under the rubric of jihad (striving) and siyar (the law governing relations with non‑Muslims). The Qur’an and Hadith contain both exhortations to fight and strong injunctions against transgression.

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“Fight in the way of God those who fight you, but do not transgress. Indeed, God does not like transgressors.”

— Qur’an 2:190

Sunni legal schools developed a complex typology of lands (e.g., dār al‑islām, dār al‑ḥarb) and associated duties. Many jurists held that military jihad is defensive in principle—protecting the Muslim community and ensuring freedom of religious practice—though they differed on offensive campaigning and treaty obligations.

Key constraints included:

• Prohibitions on killing women, children, monks, and other non‑combatants
• Requirements to offer terms or invitations before hostilities
• Safeguards for prisoners and the ethical division of spoils

Debates arose over whether rulers could legitimately wage war for reasons such as suppressing rebellion or promoting public order, and how to treat allied or protected communities (dhimmis).

Convergences and Divergences

Both traditions connect war to a transcendent moral order, require legitimate authority and some notion of just cause, and recognize protections for non‑combatants. Differences include their respective attitudes toward religiously infused warfare, classifications of enemies, and relations between religious law and secular authority. These medieval doctrines significantly influenced later European natural law and modern Islamic discussions of war and peace.

6. Early Modern Natural Law and the Law of Nations

From the 16th to 18th centuries, European thinkers reworked medieval just war ideas into more secular, state‑centred doctrines of natural law and the law of nations (jus gentium). They sought principles that could govern relations among increasingly sovereign states with diverse religions.

Spanish Scholastics and Colonial Encounters

The School of Salamanca, including Francisco de Vitoria and Francisco Suárez, confronted the ethics of conquest in the Americas. Vitoria argued that indigenous peoples possessed natural rights and political authority; mere difference of religion could not justify war.

He proposed limited just causes for war—such as defense, protection of innocent third parties, or response to grave violations of natural law (e.g., human sacrifice)—and emphasized proportionality and restraint. Critics note that these criteria nonetheless provided a moral vocabulary that could legitimize colonial expansion.

Grotius and the Secularization of Just War

Hugo Grotius’s On the Law of War and Peace (1625) is often seen as foundational for modern international law. Drawing on Roman law, theology, and practice, Grotius argued that there is a natural law binding on all peoples, discoverable by reason even if God did not exist.

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“Not only those who wage war for just causes, but even those who wage it without such cause, are bound to observe certain laws in waging it.”

— Hugo Grotius, De Jure Belli ac Pacis

Grotius expanded just causes to include not only self‑defense but also punishment and enforcement of rights (e.g., property, contracts). At the same time, he stressed the need to spare innocents and keep promises, even toward enemies.

Pufendorf, Vattel, and State Sovereignty

Later natural lawyers such as Samuel Pufendorf and Emer de Vattel further entrenched the centrality of sovereign states. Pufendorf linked war and peace to social contracts and duties arising from human sociability. Vattel’s influential Law of Nations treated states as moral persons with rights to independence, self‑preservation, and honor.

They contributed to principles that would inform diplomatic practice:

These early modern theories helped shift the focus from religious legitimacy to secular rights, sovereignty, and interstate order, while preserving and modifying just war criteria within an emerging framework of international law.

7. Enlightenment, Kantian Peace, and the Critique of War

The Enlightenment brought new critiques of war grounded in rationalism, emerging ideas of universal rights, and skepticism about traditional authority.

Rationalist and Humanitarian Critiques

Many Enlightenment thinkers questioned the glory historically associated with war. Voltaire, Diderot, and other philosophes portrayed war as irrational, fueled by dynastic ambition, superstition, and clerical influence rather than genuine necessity.

Some radical strands, including early peace societies, advocated disarmament, arbitration, and republican government as means to reduce war. Others argued that commerce and economic interdependence would civilize states, making war less attractive.

Rousseau and the People

Jean‑Jacques Rousseau proposed a complex view: war, he argued, is primarily a relation between states, not individuals, which could in principle mitigate direct enmity between peoples. Yet he also saw standing armies and secret diplomacy as corrupting, suggesting that republican self‑government and citizen militias would make wars rarer but more defensive in character.

Kant’s “Perpetual Peace”

Immanuel Kant provided one of the most influential philosophical accounts of peace. In Perpetual Peace (1795), he argued that a stable peace is not a natural condition but a moral and juridical project requiring institutional transformation.

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“The state of peace among men living side by side is not the natural state; the natural state is one of war.”

— Immanuel Kant, Toward Perpetual Peace

Kant outlined preliminary articles (e.g., no secret reservations in peace treaties, no standing armies gradually abolished, no national debts for external conflict) and definitive articles, including:

• The establishment of republican constitutions, where citizens must consent to war and thus weigh its costs.
• A federation of free states (not a world state) to provide collective security.
• Cosmopolitan right, particularly rights of hospitality and trade, limiting hostile treatment of foreigners.

Kant did not develop a detailed just war theory; instead, he aimed to show how moral principles and institutional design might gradually make wars less likely. Later liberal and cosmopolitan theories of peace, international organizations, and human rights draw extensively on this Kantian framework.

Tensions and Legacies

Enlightenment debates juxtaposed skeptical, quasi‑realist analyses of power with strong normative commitments to progress, rights, and peace. Some critics argue that Enlightenment universalism provided a moral language later used to justify imperial “civilizing missions,” while others emphasize its role in delegitimizing religious and dynastic wars and inspiring modern peace projects.

8. Classical Just War Theory: Jus ad Bellum and Jus in Bello

“Classical” just war theory refers to the relatively stable set of principles—shaped by medieval theology, early modern natural law, and codified in 20th‑century international law—that govern decisions to go to war (jus ad bellum) and conduct in war (jus in bello).

Jus ad Bellum: Criteria for Resorting to War

Though formulations vary, the following criteria are widely cited:

Debate persists about how stringently these criteria should be applied, how to interpret “aggression,” and whether humanitarian protection or regime change can count as just causes.

Jus in Bello: Constraints on the Conduct of War

Jus in bello is traditionally treated as independent of jus ad bellum: even unjust aggressors must obey rules of warfare, and their opponents are not released from such duties.

Key principles include:

These norms inform and are mirrored in the Hague and Geneva Conventions and customary international humanitarian law.

The Moral Equality of Combatants

A distinctive classical assumption, especially in 20th‑century restatements (e.g., Michael Walzer), is the moral equality of combatants: lawful soldiers on both sides are equally entitled to fight and kill enemy combatants, provided they comply with jus in bello, regardless of whether their state’s resort to war was just.

Proponents argue that this protects captured soldiers and enables workable rules of war. Critics, particularly revisionist theorists, question whether individuals fighting for an unjust cause can have the same moral permission to kill as those fighting defensively.

Classical just war theory thus provides a structured framework for moral evaluation, while leaving open deep controversies about interpretation, application, and underlying assumptions.

9. Pacifist Traditions and Nonviolent Resistance

Pacifism encompasses a spectrum of positions that reject war and often all forms of lethal violence, emphasizing alternative means of conflict resolution and resistance. It intersects with religious ethics, secular moral theory, and political movements.

Types of Pacifism

The literature commonly distinguishes:

Pacifists draw on deontological arguments about the inviolability of persons, consequentialist claims about war’s destructive effects, and virtue‑ethical concerns about character, trust, and community.

Religious Pacifist Traditions

In Christianity, some early communities and later groups (e.g., Quakers, Mennonites, certain Anabaptists) interpreted Jesus’ teachings—especially the Sermon on the Mount—as mandating non‑resistance to evil and love of enemies.

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“Do not resist an evildoer. But if anyone strikes you on the right cheek, turn the other also.”

— Matthew 5:39

In other traditions, Jainism and strands of Buddhism develop strong commitments to ahimsa (non‑harm). These commitments sometimes allow for pragmatic compromises in governance but generally condemn participation in war.

Secular and Political Pacifism

Modern secular pacifism often arises from humanitarian, socialist, or feminist critiques. Arguments emphasize:

• The tendency of war to entrench state power and class domination
• The gendered nature of militarism and its impact on social roles
• The historical record of atrocities, including targeting of civilians

Philosophers such as Leo Tolstoy and Mohandas K. Gandhi articulated influential Christian and Hindu‑inspired pacifisms that also informed political strategy.

Nonviolent Resistance

Pacifism is closely linked to nonviolent resistance, which treats nonviolent action as both morally preferable and often strategically effective. Gandhi’s campaigns against British rule, the U.S. Civil Rights Movement, and various anti‑authoritarian struggles are frequently cited cases.

Nonviolent tactics include strikes, boycotts, mass demonstrations, civil disobedience, and parallel institutions. Supporters argue these can undermine unjust regimes while reducing harm, though critics question their effectiveness against extremely violent or genocidal adversaries.

Debate continues over whether nonviolence is a universal moral requirement, a highly demanding ideal, or one strategy among others in confronting injustice.

10. Realism, Reason of State, and Strategic Thought

Realism in war ethics emphasizes power, interest, and survival over moral constraints, often challenging the practical relevance of just war norms and pacifist ideals.

Classical and Modern Political Realism

Classical realists, inspired by Thucydides, Machiavelli, and Hobbes, view international relations as an anarchic realm lacking a central authority capable of enforcing moral or legal rules. States must prioritize self‑preservation and security, even at moral cost.

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“A prince must learn how not to be good.”

— Niccolò Machiavelli, The Prince

Modern realist theorists in international relations, such as Hans Morgenthau and Kenneth Waltz, argue that moral aspirations often cloak power politics. They caution that moralistic foreign policies can provoke overreach and disaster.

Reason of State and Raison d’État

Early modern ideas of reason of state (ragion di stato) hold that rulers may justifiably act beyond ordinary moral norms to safeguard the state. This may include deceptive diplomacy, preemptive war, or alliances of convenience.

Realist reasoning typically acknowledges some prudential constraints—such as avoiding wars that would jeopardize long‑term security—but treats these as matters of calculation rather than duty.

Strategic Thought and Military Theory

Strategic theorists like Carl von Clausewitz analyze war as an instrument of policy. Clausewitz’s famous formula—war as the continuation of politics by other means—has been interpreted as both realist and compatible with moral constraints, depending on the reading.

Realist‑leaning strategic thought stresses:

• The centrality of deterrence, alliances, and balance of power
• The need to consider escalation dynamics and uncertainty
• The role of military professionalism and discipline as practical, not necessarily moral, restraints

Ethical Critiques of Realism

Critics contend that realism:

• Offers limited resources for condemning aggression or atrocities
• Underestimates the influence of norms, institutions, and public opinion on state behavior
• Risks normalizing or excusing grave violations of human rights

Defenders reply that moral frameworks must be tempered by empirical realities of power and that prudential restraint often coincides with humanitarian outcomes. Some “moderate realists” accept minimal ethical norms—such as prohibitions on genocide—while insisting that broader moralizing is dangerous or naïve.

Realism thus serves as a critical foil to more idealistic or normatively ambitious approaches in war and peace ethics.

11. Humanitarian Intervention and Responsibility to Protect

Humanitarian intervention refers to the use of military force by external actors, without the consent of the territorial state, with the stated primary aim of preventing or halting mass atrocities. The Responsibility to Protect (R2P) is a related doctrine that reframes this issue in terms of states’ duties to protect populations.

Normative Foundations

Proponents argue that sovereignty is not absolute but conditional on the protection of basic human rights. When a state is unwilling or unable to prevent genocide, ethnic cleansing, war crimes, or crimes against humanity, external intervention may be morally required.

Critics worry that such a doctrine undermines non‑intervention and may be exploited by powerful states as a pretext for regime change or geopolitical advantage.

The Responsibility to Protect

Articulated in the early 2000s and endorsed in principle by the UN World Summit (2005), R2P distinguishes three responsibilities:

R2P emphasizes that primary responsibility lies with the state itself; international action is subsidiary and ideally authorized by the UN Security Council.

Ethical Controversies

Key debates include:

• Just cause and thresholds: How severe must abuses be to justify intervention?
• Authority: Is UN authorization morally necessary, or can unilateral or regional interventions be legitimate when the Security Council is deadlocked?
• Proportionality and last resort: How should the likely harms of intervention (civilian casualties, regional destabilization) be weighed against ongoing atrocities?
• Selectivity and consistency: Does selective intervention—acting in some crises but not others—undermine the moral credibility of the norm?

Some theorists view humanitarian intervention as a natural extension of just war principles, focusing on protection of innocents beyond borders. Others argue that emphasis on military solutions diverts attention from nonviolent prevention, post‑colonial power imbalances, and structural injustices that contribute to atrocities.

The mixed record of interventions—from perceived successes like some interpretations of Kosovo (1999) to contentious cases like Iraq (2003) and Libya (2011)—continues to fuel these ethical debates.

12. Cosmopolitan and Revisionist Perspectives on War

Cosmopolitan and revisionist approaches challenge traditional, state‑centred assumptions in war ethics, focusing on individuals’ rights and responsibilities irrespective of nationality or combatant status.

Cosmopolitan War Ethics

Cosmopolitans hold that all persons have equal moral worth, and that political borders lack fundamental ethical significance. War ethics, on this view, should be grounded in universal human rights and global justice rather than state sovereignty.

Key themes include:

• Individual rights as primary: States are important mainly instrumentally, insofar as they secure or violate individuals’ rights.
• Global distributive justice: Structural injustices—poverty, resource exploitation, and unequal trade—are treated as morally relevant causes or contexts of war.
• Duties across borders: There may be obligations to protect distant strangers from aggression or deprivation, reshaping debates about intervention and aid.

Authors like Cécile Fabre and Seyla Benhabib link war ethics to broader cosmopolitan theories of democracy and human rights.

Revisionist Just War Theory

“Revisionist” theorists, such as Jeff McMahan and David Rodin, revisit core just war concepts, especially the moral equality of combatants. They argue that:

• Liability to defensive killing depends on an individual’s responsibility for an unjust threat.
• Soldiers fighting for an unjust cause are generally not morally permitted to kill their opponents, even if legally authorized.
• Conversely, some civilians who play key roles in unjust aggression may be more liable than low‑level combatants.

This leads to more fine‑grained distinctions based on intention, coercion, knowledge, and causal contribution, rather than simple combatant/non‑combatant status.

Implications and Criticisms

These perspectives have significant implications:

• Targeting and collateral damage: Liability‑based approaches may justify different patterns of permissible harm.
• Conscientious objection: Individual responsibility for unjust wars becomes central, strengthening arguments for selective refusal.
• International law: Current legal regimes, built around state sovereignty and combatant equality, might require substantial reform.

Critics argue that cosmopolitan and revisionist views:

• Are too demanding and complex for real‑world decision‑making in the fog of war
• Risk eroding protections for prisoners of war and non‑combatants by undermining status‑based rules
• May be more easily applied by powerful states to delegitimize opponents than to restrain their own conduct

Supporters respond that ethical accuracy should not be sacrificed for simplicity, and that legal frameworks can approximate individualized moral judgments while retaining practical clarity.

13. Technology, Autonomous Weapons, and Cyber Warfare

Rapid technological change has generated new ethical questions about how war is waged, who bears responsibility, and whether existing norms can adapt.

Precision Weapons and Remote Warfare

Advances in surveillance, drones, and precision‑guided munitions are often said to enable discrimination and reduce collateral damage. Supporters argue that remote systems can strike military targets more accurately and protect soldiers from harm.

Critics counter that:

• Lower political costs to the intervening side may make resort to force more frequent.
• Persistent surveillance and remote strikes blur boundaries between war and policing.
• Psychological distance for operators may affect attitudes toward killing, though empirical evidence is mixed.

Autonomous Weapon Systems

Autonomous weapon systems (AWS) can select and engage targets without direct human control. Ethical debates focus on:

Some argue that properly designed AWS could reduce human error and emotional overreaction. Others maintain that delegating life‑and‑death decisions to machines violates human dignity and undermines meaningful human control.

Cyber Warfare

Cyber operations—such as disabling infrastructure, stealing data, or manipulating information—raise questions about what counts as an “armed attack” or act of war.

Key concerns include:

• Attribution: Difficulty identifying perpetrators complicates deterrence and responsibility.
• Proportionality and discrimination: Cyberattacks on dual‑use infrastructure (e.g., power grids, hospitals) may indirectly harm civilians.
• Thresholds: Scholars debate when cyber activities surpass espionage or crime and trigger self‑defense rights.

Some propose extending existing just war criteria to cyber realms; others suggest the need for new concepts tailored to the distinctive features of digital networks and information warfare, including psychological operations and disinformation campaigns.

Overall, technological change pressures traditional frameworks to address emerging forms of harm, agency, and vulnerability, while raising the question of whether war ethics can remain technologically neutral or must evolve substantively.

14. International Law, Human Rights, and War Crimes

International law codifies many ethical principles concerning war, though the relationship between legal and moral norms remains contested.

The UN Charter and Jus ad Bellum

The UN Charter establishes a general prohibition on the use of force (Article 2(4)), allowing only:

• Self‑defense against an armed attack (Article 51)
• Security Council authorization for collective measures to maintain or restore international peace and security (Chapter VII)

Ethical debates concern preemptive versus preventive self‑defense, the scope of “armed attack,” and how strictly to interpret Security Council authority.

International Humanitarian Law (IHL)

International humanitarian law, rooted in the Geneva and Hague Conventions, regulates jus in bello. Core principles, paralleling just war theory, include:

IHL applies equally to all parties, regardless of who initiated the conflict.

War Crimes and Accountability

Grave breaches of IHL constitute war crimes, subject to individual criminal responsibility. International tribunals—such as those for the former Yugoslavia and Rwanda—and the International Criminal Court (ICC) prosecute crimes including:

• Willful killing of protected persons
• Targeting civilians or humanitarian workers
• Use of prohibited weapons in certain contexts
• Genocide and crimes against humanity (overlapping with human rights law)

Philosophers and legal theorists debate:

• The fairness of “victors’ justice” and selective prosecution
• The moral basis for command responsibility and superior orders defenses
• The relationship between war crimes and broader structural injustices not easily captured by criminal law

Human Rights and Armed Conflict

International human rights law, originally designed for peacetime, now interacts with IHL in complex ways. While some rights may be derogated during emergencies, core rights—such as the prohibitions on torture and genocide—are widely seen as non‑derogable.

Two main views exist:

• Complementarity: IHL and human rights law are seen as mutually reinforcing, with human rights norms informing interpretation of IHL.
• Specialty: IHL is treated as lex specialis—the more specific law governing combat—while human rights law sets baseline constraints.

These legal frameworks provide institutions and procedures for accountability, yet their enforcement is uneven, raising questions about the gap between normative aspiration and political reality.

15. Peacebuilding, Reconciliation, and Jus Post Bellum

Jus post bellum concerns ethical norms governing the termination of war and the transition to peace. It addresses how to end conflict justly and lay foundations for a stable, morally acceptable order.

Principles of Jus Post Bellum

While less codified than jus ad bellum and jus in bello, proposed principles include:

Theorists such as Brian Orend argue that these norms help avoid “victor’s justice” and cycles of revenge.

Peacebuilding and Institutional Reform

Peacebuilding refers to comprehensive efforts to prevent relapse into conflict. Ethical debates concern:

• The legitimacy of international administration or occupation to oversee transitions
• How far external actors may reshape political and economic institutions
• Balancing local ownership with the protection of vulnerable groups

Some models stress liberal democratic reforms and market institutions; others emphasize traditional or hybrid approaches, community‑based justice, and power‑sharing arrangements.

Transitional Justice and Reconciliation

Post‑conflict societies often face dilemmas about how to address past atrocities:

• Retributive justice through trials (domestic or international)
• Restorative justice via truth commissions, reparations, and public apologies
• Amnesties conditioned on disclosure or demobilization

Advocates of criminal trials cite deterrence, moral accountability, and victims’ rights. Proponents of restorative approaches stress healing, social trust, and the practical constraints of prosecuting widespread wrongdoing.

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“Without forgiveness, there is no future.”

— Desmond Tutu, No Future Without Forgiveness

Critics caution that emphasizing reconciliation may pressure victims to forgive prematurely or obscure structural injustices.

Jus post bellum debates thus explore how to balance justice and peace, punishment and forgiveness, sovereignty and international involvement in the aftermath of war.

16. Religious Ethics, Conscientious Objection, and Civil Disobedience

Religious traditions significantly shape attitudes toward war, peace, and individual responsibility, influencing practices of conscientious objection and civil disobedience.

Religious Ethics of War and Peace

Major religions contain both justifying and restraining strands:

• Christianity: Hosts both just war and pacifist traditions. Institutional churches often developed just war criteria, while groups like Quakers and Mennonites adopted nonviolence.
• Islam: Juristic elaborations of jihad regulate legitimate defense and conduct, while Sufi and other movements emphasize inner spiritual struggle and peace.
• Judaism: Biblical narratives include divinely commanded wars, but rabbinic law and later thought place strong limits on warfare and stress pikuach nefesh (saving life).
• Hinduism and Buddhism: Contain texts both valorizing warriors and prescribing non‑harm (ahimsa); interpretations vary across communities.
• Jainism: Articulates especially strict nonviolence, influencing broader Indian ethical thought.

These traditions inform believers’ judgments about specific conflicts and participation in armed forces.

Conscientious Objection

Conscientious objection involves refusal to perform military service or fight in particular wars based on moral or religious conviction.

Two broad forms are recognized:

Legal systems vary widely in their recognition of these claims, from full exemption with alternative service to criminal penalties.

Ethical debates focus on:

• Whether states should respect individual conscience at the cost of burden‑sharing and defense needs
• How to distinguish genuine from opportunistic objection
• Whether selective objection undermines democratic decision‑making about war or instead corrects its moral failures

Civil Disobedience and War

Civil disobedience—public, nonviolent lawbreaking to protest policies—is a common method for opposing specific wars, conscription, or weapons development.

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“One has a moral responsibility to disobey unjust laws.”

— Martin Luther King Jr., Letter from Birmingham Jail

Philosophers discuss conditions under which civil disobedience is justified: seriousness of injustice, exhaustion of legal remedies, willingness to accept legal penalties, and commitment to nonviolence.

In the war context, civil disobedience raises questions about loyalty, democratic legitimacy, and the ethics of resistance when state policies are perceived as gravely unjust or illegal under international law.

Religious and secular moral frameworks thus provide resources for individuals and groups to contest state war decisions, often at personal risk.

17. Contemporary Debates and Emerging Challenges

Contemporary ethics of war and peace engages a shifting landscape of conflicts, actors, and technologies, generating new controversies and revisiting older ones.

Asymmetric and “New” Wars

Civil wars, insurgencies, terrorism, and counterinsurgency blur distinctions between combatants and civilians, front lines and home fronts. Debates address:

• The status of non‑state armed groups and “unlawful combatants”
• Targeted killings and drone strikes outside traditional battlefields
• Urban warfare, human shields, and the protection of civilians in densely populated areas

Some philosophers argue for adapting just war principles to these realities; others maintain that the core principles remain adequate but poorly implemented.

Terrorism and Counterterrorism

The moral status of terrorism—typically defined as violence targeting civilians for political aims—is widely condemned, yet disagreement persists about:

• Whether state violence causing similar harms differs morally from non‑state terrorism
• The permissibility of emergency measures: preventive detention, enhanced surveillance, coercive interrogation
• Balancing security with civil liberties and human rights

Nuclear Weapons and Deterrence

Nuclear arms present acute ethical dilemmas. Critics claim that nuclear deterrence relies on conditional threats to commit massive indiscriminate killing, conflicting with jus in bello. Defenders argue that deterrence has prevented large‑scale war and may be morally preferable to conventional conflicts.

Debates involve disarmament, no‑first‑use pledges, and the morality of nuclear proliferation or non‑proliferation regimes.

Climate Change, Resources, and Structural Violence

Linkages between environmental degradation, resource scarcity, and conflict raise questions about preventive duties and responsibility for “slow violence” that contributes to instability. Theorists explore:

• Whether high‑emitting states bear special responsibilities for climate‑related conflicts
• The ethics of resource wars and adaptation‑driven migration
• How global justice frameworks intersect with war ethics

Global Governance and Norm Contestation

International institutions, NGOs, and transnational movements influence norms about intervention, human rights, and arms control. At the same time, rising multipolarity and nationalist movements challenge liberal internationalist frameworks.

Contemporary debates thus revolve around whether existing ethical concepts—just war, sovereignty, human rights—can accommodate these emerging challenges or require more radical reconceptualization.

18. Legacy and Historical Significance of War and Peace Ethics

The ethics of war and peace has left a substantial legacy in philosophy, law, and political practice, shaping how societies understand and regulate organized violence.

Influence on Legal and Political Institutions

Just war principles and related doctrines informed:

• The development of international humanitarian law and the law of armed conflict
• The structure of the United Nations system, with its emphasis on collective security, self‑defense, and human rights
• The creation of war crimes tribunals and the International Criminal Court

Even when states act contrary to these norms, the language of just cause, proportionality, and protection of civilians remains central to public justification and critique.

Impact on Social Movements and Public Morality

Pacifist, religious, and human rights‑based critiques of war have influenced:

• Peace movements, anti‑nuclear campaigns, and conscientious objection practices
• Debates over conscription, military spending, and arms control
• Cultural representations of war, including literature, film, and journalism

These discourses shape public expectations about acceptable wartime behavior and government transparency.

Intellectual Contributions

War and peace ethics has contributed to broader philosophical discussions about:

• The nature of rights, duties, and collective responsibility
• The relationship between moral theory and political reality
• The ethics of emergency, exception, and existential threat

It has also fostered interdisciplinary engagement among philosophers, lawyers, political scientists, historians, theologians, and military practitioners.

Continuing Significance

Despite persistent armed conflict, many analysts argue that normative and legal constraints have altered state behavior compared with earlier eras, while acknowledging regressions and hypocrisy. Others emphasize that ethical frameworks are often co‑opted to legitimize power.

The historical evolution of war and peace ethics—from ancient reflections to contemporary debates about intervention, technology, and global justice—thus offers a record of changing attempts to reconcile the realities of violence with enduring aspirations for order, rights, and peace.