12.1 Just war theory

Just war theory attempts to reconcile the destructiveness of warfare with the need for justice in international relations. It establishes ethical guidelines for when war is permissible and how it should be conducted, rooted in Western philosophy and theology.

The theory distinguishes between jus ad bellum (justification for war) and jus in bello (conduct in war). Key principles include just cause, right intention, proper authority, last resort, probability of success, and proportionality. These aim to limit war's brutality while allowing for justified conflicts.

Origins of just war theory

• Just war theory attempts to reconcile the destructiveness of warfare with the need for justice, providing a framework for evaluating the morality of armed conflicts in international relations
• Rooted in Western philosophy and theology, just war thinking has evolved over centuries to address changing political realities and moral sensibilities about the use of military force
• Seeks to establish ethical guidelines for when it is permissible to go to war (jus ad bellum) and how war should be conducted (jus in bello) to limit its brutality

Key principles of just war

Jus ad bellum vs jus in bello

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• Jus ad bellum refers to the conditions that must be met to justify initiating a war, focusing on the reasons and intentions behind the use of force
• Jus in bello concerns the rules of conduct within war itself, emphasizing the methods and means used by combatants
• The two categories are considered separately, so a war may be deemed just to initiate but fought unjustly, or vice versa

Just cause for war

• A central tenet holding that the reason for war must be morally righteous, such as self-defense against aggression, protection of innocents, or punishment of egregious wrongdoing
• Rejects wars fought for territorial gain, economic interest, or ideological supremacy as unjustified
• Requires that the injustice being fought must be severe enough to warrant the devastation of war (massacre of civilians)

Right intention behind war

• Maintains that the actual motivation for war must be the just cause itself, not ulterior motives cloaked in righteous rhetoric
• Forbids wars ostensibly fought for a just cause but actually driven by a desire for power, revenge, or material gain
• Ensures the aims of war remain limited to redressing a specific injustice rather than devolving into conquests of aggrandizement (regime change to end genocide vs land grab)

Proper authority and public declaration

• Specifies that only legitimate governing authorities, not private individuals or groups, have the right to initiate war and deploy armed forces
• Requires a formal, public declaration of war to give opposing sides a chance for peaceful resolution and to establish the parameters of the conflict
• Reinforces war as a last resort measure between states after other diplomatic options have been exhausted (UN Security Council authorization)

War as last resort

• Obligates states to pursue all feasible peaceful alternatives before resorting to armed force, including diplomacy, mediation, economic sanctions, or international pressure
• Recognizes war's destructiveness and establishes a high threshold for its initiation in international society
• Places the burden of proof on the party initiating conflict to demonstrate the necessity of war after good faith efforts at non-violent dispute resolution

Probability of success

• Demands that a war must have a reasonable chance of succeeding in its just aims to be morally permissible, not be a futile waste of life and resources
• Discourages reckless or disproportionate resort to war by weaker states against much stronger opponents
• Considers the likely outcome and costs of conflict, not only the justness of the cause, in the moral calculation (small country attacking superpower vs evenly matched adversaries)

Proportionality of anticipated benefits vs harms

• Requires that the expected good outcomes of a war outweigh its projected death and destruction, with the benefits proportional to the costs
• Seeks to minimize gratuitous or excessive harm by considering the scale, duration, and intensity of a proposed war in relation to its specific just aim
• Difficult to assess in practice due to the unpredictability of war's consequences, but serves as a restraining principle against disproportionate force (total war over a minor border dispute)

Historical development of just war tradition

Ancient and medieval contributions

• Greek and Roman thinkers like Aristotle, Cicero and Augustine grappled with the idea of just causes for war, usually focusing on defense of the state
• In the Middle Ages, Christian theologians such as Aquinas further developed just war concepts, adding the authority of the sovereign and right intention
• The idea of chivalry and codes of military conduct in feudal Europe reflected emerging jus in bello notions of restraint in war

Renaissance and Enlightenment era refinements

• Renaissance humanist thinkers and jurists like Vitoria and Grotius further systematized just war thought, incorporating it into the foundations of international law
• Enlightenment philosophers such as Locke, Vattel and Kant secularized just war principles, basing them on natural law and social contract rather than divine justice
• The rise of professional standing armies and more destructive weaponry spurred efforts to codify rules of warfare to prevent atrocities and protect civilians (Lieber Code in US Civil War)

Contemporary just war theory

Revisionist vs traditionalist approaches

• Traditionalists seek to preserve the core tenets of just war theory as a deontological constraint on the use of force, an absolutist moral framework
• Revisionists argue for a more consequentialist approach, weighing the outcomes of war and making exceptions to just war principles for the sake of a greater good
• The atomic bombings of Japan in WWII highlighted the divide, with traditionalists deeming them unjust and revisionists seeing them as necessary to end the war

Redefining jus ad bellum principles

• Modern just war theorists have sought to refine and expand the criteria for just initiation of war beyond self-defense against aggression
• Humanitarian intervention to stop atrocities or rescue innocents has been proposed as a new just cause for war (NATO intervention in Kosovo)
• Pre-emptive self-defense against imminent threats and preventive war against longer-term dangers have been more controversially floated as potential just war rationales (US invasion of Iraq)

Expanding jus in bello norms

• Contemporary laws of war have further developed jus in bello principles of discrimination between combatants and civilians and proportionality in the use of force
• Prohibitions on specific inhumane weapons (chemical weapons, landmines) and tactics (perfidy, human shields) aim to reduce suffering in war
• The principle of military necessity, that the force used must be essential to achieve a legitimate military aim, seeks to restrain gratuitous death and destruction

Emergence of jus post bellum

• A third category of just war thinking dealing with the ethics of ending wars and transitioning to peace has gained prominence in recent decades
• Jus post bellum concerns include pursuing war crimes trials, rebuilding damaged societies, establishing stable governments, and promoting reconciliation
• Failures to plan for jus post bellum after the 2003 Iraq War and 2011 Libya intervention highlighted the importance of this new dimension of just war theory

Just war theory in international law

UN Charter and use of force

• The UN Charter, foundational to modern international law, prohibits the use of force against states except in self-defense or with UN Security Council authorization
• This reflects a restrictive jus ad bellum, with aggression outlawed and only limited exceptions for just war against international threats to peace
• In practice, the self-defense exception has been interpreted more broadly by states, and the UN has authorized force beyond strict self-defense (Korean War)

Geneva Conventions and conduct in war

• The Geneva Conventions enshrine jus in bello principles into international humanitarian law, with detailed rules for the treatment of captured or wounded combatants, civilians, and other protected persons
• Prohibitions on torture, summary executions, attacking civilian targets, and other war crimes operationalize just conduct in war
• Additional Protocols to the Conventions have expanded these protections and adapted them to new forms of warfare (civil wars, guerrilla fighters)

War crimes tribunals and prosecution

• International criminal tribunals (Nuremberg, Yugoslavia, Rwanda) and the International Criminal Court enforce just war principles by prosecuting egregious violations as war crimes
• These venues hold individuals accountable for unjust initiation of war (crimes against peace) and unjust conduct in war (crimes against humanity, genocide)
• The prosecution of national leaders for aggression and atrocities committed in war gives teeth to just war norms and creates deterrence, but enforcement remains sporadic

Challenges to just war framework

Changing nature of warfare

• The evolution of warfare from pitched battles between armies to more complex conflicts involving civilians, urban settings, and prolonged occupations strains just war principles
• Insurgencies, terrorism, and asymmetric warfare pose challenges for upholding discrimination and proportionality in fighting
• The erosion of clear spatial and temporal boundaries of war complicates notions of just initiation and termination of conflicts

Rise of non-state actors

• Just war theory's state-centric framework is challenged by the growing military capabilities of non-state groups like terrorist networks, militias, and corporations
• The principle of proper authority is undermined when non-state actors can initiate and wage war without formal declarations or accountability
• The moral status and culpability of irregular fighters not in uniform or part of national armies creates dilemmas for jus in bello

Technological advancements in weapons

• The destructive power of modern weapons, from nuclear arms to precision munitions, raises questions about the possibility of discrimination and proportionality in war
• Emerging technologies like drones, cyber attacks, and autonomous weapons present new moral hazards not well addressed by existing just war principles
• The risk of war becoming too easy or sanitized with standoff weapons that lower costs to aggressors threaten the spirit of just war thinking

Difficulty of proportionality assessments

• The complex and unpredictable ripple effects of war make it hard to weigh anticipated benefits and harms as demanded by the proportionality principle
• Leaders often lack sufficient information to make accurate cost-benefit analyses before initiating war, and the fog of war compounds this challenge
• Psychological biases like the optimism bias and sunk costs fallacy can distort evaluations of the proportionality of continuing a war once begun

Alternative approaches to just war

Pacifism and non-violence

• Pacifists reject just war theory's premise that war can ever be morally justified, arguing that violence is inherently wrong and begets more violence
• Non-violent resistance is offered as an alternative means of securing justice that avoids the death and destruction of war (Gandhi's satyagraha strategy)
• Critics argue pacifism is morally untenable in the face of violent aggression and can enable greater injustice, while advocates see it as a higher ethical model

Realism and amorality of war

• Realists reject the application of moral principles like just war theory to the anarchic realm of international relations, seeing war as an inevitable tool of power politics
• For realists, the ethical niceties of just war are irrelevant to the security imperatives of states, which will use force whenever it serves their interests
• Critics argue realism is a descriptive theory that does not negate the moral responsibility to govern war, and that unchecked realpolitik enables aggression and atrocities

International society and shared norms

• The international society approach sees just war principles not as abstract philosophy but as shared norms that emerge from the interactions and common interests of states
• Just war is an evolving customary ethic embedded in international social structures and institutions, from professional military codes to the UN Charter
• This approach emphasizes how the practice of war is restrained by informal standards of legitimacy and appropriateness shaped by international society, not just codified laws

Case studies of modern conflicts

Applying just war criteria

• The 1999 NATO intervention in Kosovo to halt ethnic cleansing by Serbia is often cited as a case of humanitarian intervention meeting jus ad bellum standards
• The 2003 US invasion of Iraq was more contested, with debates over whether it met just cause, right intention, and last resort criteria
• The tactics used by Sri Lanka in the final stages of its civil war in 2009, including shelling civilian areas, raised questions of jus in bello violations

Controversies and gray areas

• Israel's use of targeted killings and Lebanon and Gaza wars have been debated in terms of discrimination and proportionality in asymmetric urban warfare
• The US drone campaign against Al Qaeda and ISIS in multiple countries poses challenges for just war principles of proper authority and imminence of threat
• Russia's annexation of Crimea and intervention in Ukraine have contested the line between just self-defense and aggression in an age of hybrid warfare

Lessons for ethical use of force

• Rigorous public debate and clear communication are essential to build legitimacy for military action under just war principles in a democracy
• International organizations like the UN, while imperfect, remain important channels for upholding just war norms and authorizing the use of force
• Developments in international law and institutions (R2P, Peacebuilding Commission) can help translate just war theory into practice, but still face political obstacles
• Creative approaches (sanctions, humanitarian aid, peacekeeping) can sometimes uphold the spirit of just war theory while avoiding the costs of full-scale war
• While just war theory cannot always offer perfect guidance, its principles remain valuable tools for morally evaluating and constraining the destructiveness of war