To fight or not to fight – that is the central question of Just War Theory.
Though wars are usually waged in pursuit of man’s basic needs – land, wealth, a beautiful face – a theory developed in the western world suggesting that they need not always be fought for selfish reasons. Some wars might in fact be just, fought in light of the virtues of a people rather than their vices.
This philosophy delving into that lowest of human conditions required the heights of human intellect to develop. Though often framed as solely a Christian philosophy, Just War Theory’s foundations stretch back to thinkers in antiquity. Typically the tradition is traced to eminent Christian theologians like Thomas Aquinas and Augustine of Hippo, but some of its key ideas have roots in pagan Greece and Rome. Plato, Aristotle, Cicero, and others hinted at concepts that can be understood in the context of Just War Theory.
A thorough review of the history of Just War principles will help us trace their development throughout antiquity and understand Augustine’s and Aquinas’ formulations not as wholly unique concoctions forged in a vacuum, but rather the culmination and perfection of ideas from pre-Christian as well as Christian thinkers. In Rewriting the Just War Tradition author Cian O’Driscoll writes, “Augustine did not create just war thought ex nihilo, but instead built upon classical sources.”
Let’s explore how the ancient world laid the foundations for a conception of ethical war.
The Basics of Just War Theory
First let’s lay out the basics of Just War Theory.
Just War Theory can be broken into three categories: Jus Ad Bellum (right to wage war), Jus in Bello (proper conduct in war), and Jus Post Bellum (justice after war).
The vast majority of scholarship has focused on the category of Jus Ad Bellum in an attempt to answer the question “when is it just or appropriate to go to war?” There are varied formulations of the Jus Ad Bellum category, but a simplistic version addressed by Aquinas in the Summa Theologica lays out three criteria in order for a war to be waged justly: (1) it must be waged for a just cause (the party declaring war must have suffered some wrong by the opposing party), (2) it must be sanctioned by a proper authority (a body or individual given the powers to do so), and (3) it must have the right intent (promoting good and avoiding evil, for example).
Jus in Bello explores the proper conduct within war i.e. what is morally acceptable to do while at war. The Geneva Convention codes are perhaps the most well-known examples of this. The medieval Code of Chivalry also contains examples of this principle in that it discusses how combatants should engage one another during combat. Jus in Bello addresses everything from how to treat prisoners to what targets are morally acceptable during war.
Finally, Jus Post Bellum addresses how wars should be ended and the aftermath of war. This principle is the least explored and is often omitted from Just War scholarship altogether. Nonetheless, it is an important aspect of the Just War Theory because it explores how to prevent animosity between foes and mitigate future conflicts.
Let us now explore what Just War principles the Greeks and Romans developed, allowing later Christian thinkers to build off of.
Just War in Ancient Greek Thought
Several prominent Greek writers and thinkers touched on topics relating to Just War. Within the works of Herodotus, Thucydides, Plato, and Aristotle, Just War concepts can be found in a primordial state. Though these writers did not explicitly set out to explicate these topics, their works in history and philosophy tangentially acknowledged just and unjust causes and conduct in war.
Within the work of Herodotus, the “father of history,” one can find a rudimentary ‘just cause’ principle (jus ad bellum), though not necessarily as one would contrive it today. Herodotus agreed with modern readers that “No one is fool enough to choose war instead of peace,” however Herodotus’s conception of cosmology influenced his beliefs about what constituted just cause when peace was not an option.
Herodotus believed that the Gods were ultimately responsible as the “first cause” for all major events, war included. The Gods sought to maintain a balance in the cosmos, and certain actions disrupted this balance. Wars in general often disrupted the natural order. Herodotus laments “In peace sons bury their fathers and in war fathers bury their sons” – a clear reversal of normal events [4]. Wars of conquest were particularly disruptive to the comic balance, however. His description of the Persian Wars displays this sentiment, as he believed these “unjust wars” were a result of hubris, of “reaching for something that is not proper for mortals” [3]. One can glean from his writings on such events that his worldview posited that just wars were wars that the gods approved of and unjust wars were wars that the gods did not approve of.
The other great Greek historian Thucydides disregarded the Gods or cosmos as the sole progenitors of war. Thucydides placed the impetus of war in human nature: “the cause of war is not outside humanity, it is within humanity itself.” Humans, according to Thucydides, were driven by three factors: philotimo (“love of honor”), fear, and necessity. Wars, according to him, were not capable of being contained – they were inevitable because these factors would always drive men to compete for honor or resources [3]. In his History of the Peloponnesian War, Thucydides stated: “the growth of the power of Athens and the alarm which this inspired in Sparta, made war inevitable.”[6] Though Thucydides assigns the cause of war to inevitable forces within man, his rejection of war as the result of cosmic or godlike forces progresses Just War thought from an issue of heavenly bodies to human ones. His recognition that the cause of war lies within mankind would have been favorable to Christian philosophers of Just War Theory centuries later.
Later, Plato concurred with Thucydides’ idea that saw human nature as the driving force behind war, however he rejected the idea that war was inevitable. Plato posited that the aggressive nature of man, his thumos, was controllable. The thumos was necessary to defend the polis from outside invasion but needed to be limited because it could destroy the polis through gratuitous aggressive acts. Plato explains that war should be used to cultivate this thumos by training “young guardians,” and cultivating their educational development by teaching them to correctly bring “balance of the soul, which is the primary source of justice.” Here we sense a dichotomy in that the thumos was simultaneously a cause and a remedy to war. In a related manner, Plato argued that war was often necessary to maintain independence of a particular polis, since communities were often surrounded by unjust aggressors. [3]. The philosopher warned against engaging fellow Greeks in battle, however – war should be reserved only for barbarians:
“[W]hen Greeks fight with barbarians and barbarians with Greeks, we’ll assert they are at war and are enemies by nature, and this hatred must be called war; while when Greeks do any such thing to Greeks, we’ll say that they are by nature friends, but in this case Greece is sick and factious, and this kind of hatred must be called faction. This creates two distinct categories of conflict: the first is war ‘proper’, which is natural; the second is faction, which is unnatural.” [8]
Plato’s distinction between ‘natural’ and ‘unnatural’ wars can be interpreted through the Just War lens as ‘just’ and ‘unjust’ wars, constituting a jus ad bellum principle. Plato’s justification for war differs from Aquinas’s in that he views the identity of the combatants as important as the circumstances leading to the conflict.
Plato also hints at principles in the jus in bello category of Just War: proportionality and non-combatant immunity. Proportionality is the concept that measures taken during war should be commensurate with the end goal of the combatants – only certain levels of force are morally acceptable in a given circumstance. This usually takes the form of rules for what can and can’t be done during combat. Non-combatant immunity refers to the practice that certain classes of people were off-limits as targets during warfare. Plato writes:
“Therefore, as Greeks, they won’t ravage Greece or burn houses, nor will they agree that in any city all are their enemies – men, women, and children – but that there are always a few enemies who are to blame for the differences. And, on all these grounds, they won’t be willing to ravage lands or tear down houses, since the many are friendly…”
In the above passage we see that rules of conduct were to be followed against fellow Greeks (not ravaging or burning down houses) and that a distinction was to be made between combatants and noncombatants (“there are always a few who are to blame…the many are friendly…”). Though undeveloped, we see that some principles of jus in bello were postulated long before it was defined by later thinkers.
Plato’s student Aristotle is traditionally ascribed as one of the chief originators of Just War concepts. In Politics, Aristotle lays out that self-defense is a legitimate cause for war:
“The proper object of practicing military training is not in order that men may enslave those who do not deserve slavery, but in order that first they may themselves avoid becoming enslaved to others.” (Politics, Book 7) [7]
Like Herodotus, Aristotle saw war as intertwined with the cosmos. Depending on the telos (“ends” or “purpose”) of a war, that war could either bring harmony or disharmony to the universe. The philosopher wrote in Ethics that “We make war that we may live in peace.” [12]
Aristotle viewed war as establishing natural hierarchy, which sometimes included acquiring loot and slaves; he argued that some men were naturally destined to be enslaved, and that war ensured “mastery only over those who deserve to be slaves.” [4] The suggestion that slavery could be justified is certainly an ethical disconnect between Aristotle’s worldview and that of later Just War theorists. Congruent with Plato, Aristotle believed that war was necessary to prevent Greeks from being ruled by barbarians, again a type of self-defense justification for war and a nod to the “natural hierarchy” he believed was inherent in the cosmos.
In summation of his beliefs, Aristotle recounts just causes for war in Rhetoric:
“The following are arguments for making war on somebody: that we have been wronged in the past; and no that opportunity offers ought to punish the wrongdoers; or, that we are being wronged now, and ought to go to war in our own defense – or in defense of our kinsmen or our benefactors; or, that our allies are being wronged and we ought to go to their help; or, that it is to the advantage of the state in respect of glory or wealth or power or the like” [4]
Aristotle lays out several reasons that might constitute just cause: being wronged by an enemy directly, helping allies who are attacked, as well as self-defense; the last reason he states – war for “glory or wealth or power” – is foreign to Just War Theory today and is not seen as a legitimate just cause. Nonetheless, Aristotle’s reasoning as it relates to Just War Theory is the most developed of all the Greek thinkers preceding him.
Just War Principles as Greek Cultural Practice
Apart from the great thinkers and writers who contributed to Just War thought, Greek culture likewise incorporated many practices that implicitly recognized Just War principles.
That war must be declared by the proper authority was a fundamental precept in Greek society as early as the fifth century BC, representing an early adoption of a jus ad bellum principle. The sole authority with the power to declare war was the polis with the backing of the demos (the people). Private individuals did not possess this authority, and rogue generals who tried were punished. In Athens, the ecclesia (the “popular assembly”) held this authority. As Stockton notes in The Classical Athenian Democracy, “It was the ecclesia alone which took the final decisions on declaring war or making peace.” [4] There was also a ritualistic aspect to the classical Greek understanding of proper authority. Often various religious rites were necessary before a polis could undertake military action. These rituals ensured the gods’ blessing for a war or warned the Greeks if the gods’ condemned their actions. Thus war in ancient Greek society needed the backing of the demos/polis and the theoi (gods) in order for it to be considered legitimate.
Another tenet of just war theory, jus in bello, usually understood as “right conduct in war” was present in ancient Greek society. This took the form of two principles, discrimination and proportionality.
Discrimination usually took the form of noncombatant immunity, where certain classes were protected from violence, like priests or diplomats. Prisoners taken during pitched battle were also spared from execution while subdued. Other forms of discrimination existed, like the designation that certain places and times were unfit for war. Temples, for instance, were sacred areas set apart from the world of mortal beings. They were deemed asylia, or precincts of asylum. Greek belief posited that everything within this sacred space would enjoy divine protection, therefore soldiers or refugees were guaranteed shelter as long as they remained within these sanctuaries. Adversaries usually respected these rules because they were fearful of divine vengeance upon those that violated a temple. Certain times were also believed to be unfit for war, like during the pan-Hellenic games and other festivals [4].
Proportionality was another jus in bello principle that Greek norms hinted at. Certain forms of combat such as the bow and arrow were considered “barbaric” or effeminate – no respectable Greek soldier would fight in this manner. Ancient Greek tragedian Aesychelus highlighted the dichotomy of fighting styles between the Greeks and Persians. The Greeks chose to “stand and fight in close array with spear and shield,” while the Persians had a proclivity to fight from a distance with “bows and sharp arrows.” Philosopher Euripides stated, “The test of manly courage is not with a bow, but the firm foot, the unflinching eye, when the spear drives its hurtling furrow through the ranks.” [4] The insistence that Greeks fight in a certain way is a precursor to later concepts of proportionality where combatants were expected to conform to rules during battle.
Finally, Greek culture had practices that respected the concept of jus post bellum, an often overlooked aspect of Just War Theory. Jus post bellum deals with how wars are settled and the after effects of a conflict. In classical Greece, the practice of erecting battlefield trophies allowed combatants to settle on a clear victor while drawing a definite end to the conflict. O’Driscoll writes:
“It was standard practice for the victorious army to erect a rudimentary trophy immediately after they had prevailed and fighting ceased. These trophies typically took the form of a tree stump or wooden post, fastened with a cross-beam from which the victors hung the captured arms and armor of the slain enemy. Weapons were, of course, a source of prestige in Greek life. Nothing symbolized a glorious triumph like the sight of a now dead, but once feared, enemy’s shield dangling from a trophy.” [4]
Trophies were usually constructed of wood or other decomposable materials so that “the memorial of the enmity, lasting as they would for only a brief time, should quickly disappear…” [4]. After a trophy was placed upon the battlefield signaling the end of a conflict, the vanquished army would send envoys to plead for their dead. Victors usually complied with their requests, understanding that burial rites were a sacred duty of any Greek. Their collaboration fostered a mutual respect between combatants that was the first step toward reconciliation.
We can see that the seeds of just war theory were developing in the social norms and military practices of ancient Greek society. The Romans would likewise touch on similar philosophies long before Just War Theory was formalized into the philosophy we see today.
Just War in Roman Thought
In addition to Greece, Roman scholars also contributed to Just War thought, notably famed orator, statesman, and lawyer Cicero. Cicero wrote about Just War principles in the 1st century BC in De Officiis (On Duties), his treatise on living a moral life, and was the first to actually coin the term jus bellum – “just war.” Therefore Cicero can be understood as first to explore Just War Theory as its own topic in philosophy.
The statesman argued that war should advance a higher good – a moral good – rather than simply serving the political interests of the state. Because war should aim for the good, it should not be used gratuitously for the whims of power-hungry tyrants but only in circumstances when absolutely necessary. Cicero pressed that war should only ever be a last resort:
“There are two types of conflict: the one proceeds by debate, the other by force. Since the former is the proper concern of a man, but the latter of beasts, one should only resort to the latter if one may not employ the former.” [10]
Like Aristotle, Cicero believed that war disrupted the natural state of man, which was peace. Therefore wars should be waged in order to restorethis natural state. Cicero writes, “Wars, then, are to be waged in order to render it possible to live in peace without injury.” [10]. Cicero advances a jus ad bellum argument for war by adding that religion and self defense are the only worthy causes to go to war: “No war can be undertaken by a just and wise state, unless for faith or self-defense.” [5] The orator argued that even preemptive wars could be just wars due to the possibility that the increase of Roman imperium meant a more secure world. These, then, were defensive wars and restorative to peace. [8]
Cicero also touched on a jus in bello principle, namely proportionality. He claimed that captives should be spared execution if they fought honorably: “those who were not cruel or savage in warfare should be spared.” [10] He also cautioned the use of treachery and poison during war due to their dishonorable nature. Cicero’s value of honor shows he placed importance on the behavior of soldiers during wartime, a firm jus in bello mindset.
Just War Principles as Roman Cultural Practice
Like in Greece, Rome’s cultural practices also contained elements of just war. Rome continuously tried to frame their wars as non-aggressive, or as wars that liberated oppressed peoples from tyranny. Livy wrote:
“There was one nation in the world which would fight for the liberties of others at its own cost, with its own labor, and at its own danger. It was even ready to cross the sea to make sure there was no unjust rule anywhere and that everywhere justice, right, and law would prevail.” [11]
Later in his Republic, Cicero would follow Livy’s sentiment and claim that, by “defending their allies, [Romans] have ended up as masters of the world.” [11] These statements hint that Rome maintained the perception that they were a just nation who only fought just wars. Rome’s wars, according to its citizens, were always fought for “just and pious” reasons. [5]
In a more concrete sense, Rome’s cultural traditions upheld the jus ad bellum principle of proper authority. Usually this took the form of the religious tradition of “fetial law.” For a war to first be declared, the “guilty” party was given thirty-three days to address the concerns of Rome. If the issues were not addressed after this time, war was formally declared with full approval of the Roman pantheon. [5] Other religious traditions sought to ensure approval from the gods, like observing the entrails of recently sacrificed animals to discern the will of the gods before declaring war. [11].
Conclusion
From the writings of popular Greek and Roman philosophers we understand that the Just War tradition was not a completely unique philosophy of early Church figures like Augustine. Though early Christian development was extremely significant and it fleshed out the theory to its recognizable form today, earlier writers touched on many Just War principles in the Greek and Roman world. Therefore we can understand the theory as a progression across millennia, a theory with many contributors. Similar to how Aquinas “baptized” the writings of Aristotle in his Summa Theologica, early Christian authors “baptized” contributions to Just War Theory from antiquity, taking the Good and True from the pagan world and integrating it into Christian philosophy.
Sources:
[1] https://iep.utm.edu/justwar/
[2] https://en.wikipedia.org/wiki/Just_war_theory
[4] https://www.jstor.org/stable/43868836?read-now=1&seq=1#page_scan_tab_contents
[6] 1.23, Strassler.
[7] Politics, Book 7
[10]Marcus Tullius Cicero, On Duties I. 34-35. eds. and trans. M.T. Griffin and E.M. Atkins (Cambridge 1991), pp. 14-15.”
[11]
https://ifk.uchicago.edu/news/the-romans-just-wars-and-exceptionalism
[12] Nicomachean Ethics book 10
Well done.