The Morality of (Killing in) War

Updated: Sep 2

Is it right to kill in Wartime? Welcome back to part 5 of our series on the moral permissibility of the taking of life. In many of the world’s moral codes, killing in peace is differentiated from killing in war. Today, we will take a look at the morality of warfare to understand in what circumstances we are justified in killing or harming other people during inter-community conflicts, and what, if any, limitations on the infliction of harm are morally required. Before we dive in, though, let’s pause and define what we mean when we talk about war and warfare.

What is War?

‘War’, as we mean it here, is the armed and violent conflict between communities over some point of contention. Or as Carl von Clausewitz famously said in ‘On War’, “War is the continuation of political policy by other means”. This insight is quite important as it tells us that war is not simply a senseless outpouring of violence. Instead, war is the unleashing of violence for a particular purpose that has not been able to be secured by non-violent means.

This does not mean that wars always start for good reasons, that the leaders always have clearly defined objectives at the start, or that the titular leaders can clearly choose between peace and war. But it does mean that wars are waged and fought because the participants do not believe that they can achieve their objectives without violence, and they collectively think that the benefits of victory will outweigh the costs. As Clausewitz said, “War, is an act of violence intended to compel our opponents to fulfil our will” (Von Clausewitz, 2008).

War Represents a Dual Failure

Wars represent a failure on behalf of the participants to achieve their objectives by non-violent means. This failing is a failing on behalf of both the aggressor and the defender. In the case of the aggressor, war represents a failure to convince their opponent to give in, either by inducements or via the coercive threat of irresistible force. Thus, the aggressor fails when they are not able to convince their opponent to submit to their will, citing the principle of might equals right. Thucydides expressed this best in his history of the Peloponnesian War when, during the siege of Melos, he recounts the Athenians saying, “The strong do what they can, and the weak suffer what they must”. Thus, the aggressor’s job is to convince their opponent to give in to their demands by demonstrating that the cost of resistance is high while the benefits of submission are manifold. This strategy can be seen in the successful German occupations of Denmark and Holland and the Mongol invasions, where many strong cities surrendered before their approach to avoid destruction.

In the case of the defender, the failing is similar in that they have failed to convince their opponent to give up their demands by offering inducements or presenting or possessing sufficient force to ensure that the likely cost of a violent confrontation is too high compared to the expected benefits. The position that weakness only invites aggression can be traced at least as far back as the Roman Emperor Hadrian, who is reported to have sought “peace through strength or, failing that, peace through [the] threat [of war]” (Speller, 2004). A more recent example of this principle in action was that of the late US president, Ronald Reagan, who based his policy of deterring war with the Soviet Union on the policy of “Peace through Strength”, originally championed in the Americas by George Washington and Alexander Hamilton (Wood, 2015; Rozell, 2000; Hamilton, 1999).

There is No Middle Way

Thus, when wars break out, both sides have already failed. Yet, it is not always possible to avoid wars due to the inherent unpredictability and the tendency for misjudgement in human affairs. Therefore, if a conflict occurs, both the leaders of nations and the individual members of society must clearly understand the moral implications of their actions or lack of action.

As will have become apparent to readers of this series, Codist ethics see the act of killing in either peace or war to be fundamentally morally neutral. The act of killing or harming either a person, a plant or an animal is neither right nor wrong in-and-of-itself. Instead, the consequences of acting or not acting make the act morally right or wrong. To this end, we use the Moral Decision-Making Framework described in The Code to examine the likely consequences of each choice. Looking to see if the outcomes will be positive, negative or neutral to us and our families (RP1’s) and if the consequences will be harmful to our communities. In each case, a negative outcome for either our families (RP1’s) or our community is only allowed if it is essential to avoid a worse outcome.

In the case of war, this means that to wage either defensive or offensive wars, we need to judge that the potential harm from the conflict is less than the harm from not fighting. This calculus involves an assessment of both your strength and the strength of your opponent now and in the future. Essentially, Clausewitz’s maxim that ‘wars are fought to disarm your enemy’ holds true. Or to, put it another way, we wage wars not to destroy our enemies but rather to destroy their ability to harm us. This objective can be achieved only in two ways. One, by the destruction of your enemies’ ability to threaten you. Or two, through the destruction of their desire to threaten you.

This mirrors the advice of Herennius at the battle of Claudine Forks where the Samnites, having surrounded the Roman army, debated what to do with them. Herennius suggested that either “they let them go unharmed or otherwise kill them all”, stating that the middle course is “a policy that neither wins men friends nor rids them of their enemies” (Livy & Heinemann, 1926).

A more modern example can be found in the example of Germany in the twentieth century. At the completion of the First World War, the allied powers imposed a harsh peace on the members of the Central Powers (in particular, Germany, Austria and Hungry) and attempted to prevent their rearmament via restrictions on the size of their militaries. While there were elements of the Clausewitzian theory at work, they adopted a middle course as they neither destroyed the ability of the Central European Powers to wage war nor made them into friends. This is shown by the fact that these same nations could rearm and directly threaten their former conquers only twenty years later.

At the conclusion of the Second World War, a different approach was tried. While, at first, there was talk of reducing Germany to a deindustrialised nation under the Morgenthau Plan. After an initially harsh peace, the western allies allowed their former enemies to join them as equal partners. They helped them rebuild their economies and militaries, and in the end, turned them into friends and allies, which they have remained for the last 75 years.

On the other hand, if the Germans had won the war and implemented their Neuordnung (New Order) and Generalplan Ost (General Plan East) consisting of the ethnic cleansing and perhaps genocide of 31 million Eastern Europeans (Kay, 2006). A peace built on the practical threat and occasional infliction of violence would have likely been imposed on Europe, similar to that of the ‘Pax Romana’, during which the legions enforced peace at the point of a sword. If this brutal ‘Pax Germania’ would have proved as beneficial to the victors as the more moderate ‘Pax Americana’, it must (thankfully) remain as conjecture. Yet it is worth noting that both the ‘Pax Americana’ and the ‘Pax Romana’ both resulted in unprecedented peace and economic prosperity (Coombes, 2007`), so either method may have proved been beneficial in the long run.

The Conduct of War

The ultimate aim of disarmament or threat neutralisation informs the moral choices we make in the waging of war. Essentially, the level of violence used against an enemy and if we target military, political or civilian targets all lead back to the key questions. How can we resolve this conflict in a way that;

  1. Those who were my enemy will cease to be a threat to me and mine in the future and

  2. How can I do so with the minimum harm to the members of my family and community?

These questions are the moral questions that should preoccupy us in consideration of the conduct of war. Killing or harming members of the hostile community is an unavoidable part of war and warfare, and while war itself is generally a great evil once it has begun. It is not necessarily morally wrong to conduct terror raids, execute prisoners, use chemical, biological or other non-conventional weapons or do anything else that we believe is likely to bring the war to a swift conclusion. In each case, the moral correctness of the decision is based (as with all other questions of harm) on the likely effect on the long-term welfare of your family and community. This moral position does not mean that we are advocating for the maximum level of brutality and force possible in conflict, but rather suggesting that every option should be on the table in the pursuit of lasting peace.

That said, while much can be said for the effective concentration of all available force against an enemy, it is far from clear if excessive brutality is effective in the aim of destroying an enemy’s will or ability to fight (Melson, 2011; CMH, n.d.). With at least some evidence pointing to greater brutality resulting in increased resistance (Ferguson, 2004) and some evidence pointing in the opposite direction (Adena, Enikolopov, Petrova, & Voth, 2020).

Using anti-partisan operations in WW2 as an example, the German occupation forces were noted for their brutality. Yet as SS-General Wolff put it, “The destruction of villages, [and] killing people even if proven to be partisans, rapidly destroyed our credibility and increased resistance against us” (Melson, 2011). Though it must also be noted that the Italians generally followed a far more lenient approach in anti-partisan operations and yet still faced stiff resistance (CMH, n.d.).

This ambiguity around the effectiveness of brutality is also present in the allied bombing campaigns against Germany, which resulted in 300,000 killed, 780,000 wounded, and 7,500,000 made homeless (Robert F. Futrell, 1989; Julius, 2002). The post-war analysis of the bombing campaign suggested that it was ineffective at breaking German morale or combat ability (Julius, 2002; Hansell, 1986). With John Kenneth Galbraith, who analysed its effects for the US military after 1945, going so far as to say it was “one of the greatest, perhaps the greatest, miscalculation of the war” (Adena, Enikolopov, Petrova, & Voth, 2020; Overy, 2015). Yet later studies have had different interpretations, with some studies showing that the campaign was at least somewhat effective at reducing civilian and military morale (Adena, Enikolopov, Petrova, & Voth, 2020).

Therefore, while any action that leads to the achievement of the dual objectives of minimising harm to ourselves and eliminating the threat from our opponents is right, wisdom will need to be used in tailoring the approach to the situation. Remembering that despite the passions of the moment, in most cases, we will have to live, work, and trade with our former enemies once the fighting is over. ‘The wheel of fortune turns as it will, and the victor may at any moment be cast down’ (Boethius, 1999); thus, moderation is often the best policy.


In essence, the Codist view on war can be summed up by the maxims, ‘wars are avoided and won by strength’, and that ‘the only failure worse than fighting a war is to lose a war’. War is an eventuality that should be avoided whenever possible. When it does break out, it represents a failure of both the attacker and the attacked. Both sides’ interests lie in the avoidance of armed conflict and the harmful effects concurrent with that evil occurrence. Once the fighting has started, each side has a responsibility to fight as best as they can to find an answer to the two moral questions of war. Namely, how to resolve the conflict in a way that;

  1. Their enemy will cease to be a threat to their families and communities in the future and

  2. How can they do so with the minimum harm to the members of their own family and community?

Any and all means to achieve these outcomes are morally right no matter how violent, brutal or otherwise detestable they may be. These actions’ moral permissibility is contingent on the results of those actions being likely to lead to positive or at least not adverse outcomes to the actor’s families and communities in the long run, not on the horrific consequences of the moment.

We also sound a caution regarding the dangers of taking the middle path between destroying your enemy by force and destroying their enmity by friendship. Both modern and ancient examples are provided, showing that the middle path neither wins men friends nor rids them of their enemies. Instead, the middle path is shown to only move the conflict further down the road, often leading to greater and more destructive war in the future.

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