Historically, peace is more frequent than war: most rivalries between human groups – whether organizations, communities, or states – do not lead to armed conflict. War or conflicts of all kinds are costly, risky, and potentially destructive. Understanding why war breaks out therefore requires explaining not only why tensions exist – they are almost permanent – but especially why the mechanisms that prevent violence from occurring stop working, and make a shift to war acceptable.
First, the idea of a single cause of war is misleading. Armed conflicts rarely arise from a single event or sudden decision. They more often result from a gradual deterioration of peace, during which a series of institutional, political, and social barriers are progressively broken. War then appears less as a moment of rupture than as the culmination of a trajectory. From this point of view, peace is not the absence of tension; it is an unstable balance.
Secondly, the question of the justification for war. The actors who engage in war always have a story. In other words, both states and armed groups invoke justifying narratives – fighting against terrorism, national defense, stabilization, or liberation. These narratives are not necessarily deceptive, but they rarely provide a complete explanation for the shift to violence. An analysis of the reasons for conflicts must therefore go beyond the declarative, to identify the deeper mechanisms that make violence first possible, then acceptable.
Reading war as a trajectory, rather than as an event, allows for a better understanding of why it remains a constant possibility in human history.
An article-subtitle: “A simple map: three main families of causes”
Three main mechanisms structure this shift from peace to war, progressively making compromise impossible.
The first refers to grievances, that is, economic or political injustices that fuel collective mobilizations. Armed conflicts are more likely to emerge when entire groups perceive themselves as consistently disadvantaged in access to resources, power, or recognition. When these frustrations become collective and lasting, violence can appear as a means to obtain redress or visibility. The Sri Lankan conflict illustrates this. From the 1950s, several language and administrative policies marginalize the Tamil minority in access to public jobs, higher education, and political representation. This accumulation of inequalities gradually fuels the radicalization of a part of the Tamil movement and contributes to the formation of the Liberation Tigers, who will lead an armed insurgency for years.
The second mechanism concerns the opportunities for war. Frustrations alone are not enough to produce armed conflict; it is also necessary for the violent option to become materially feasible. Research shows that conflicts are more likely when the costs of opportunities are low – for example, in contexts of poverty or unemployment – and when sources of funding exist. Exploitable natural resources, illicit economies, or control of strategic territories can provide armed groups with the means to sustain a lasting mobilization. The civil war in Sierra Leone is an example of this, with the Revolutionary United Front rebels managing to finance their insurgency through control of alluvial diamond deposits. These resources allow them to buy weapons, recruit fighters, and prolong the war despite the absence of massive popular support.
The third mechanism concerns the institutional structures that govern conflict management. Societies normally have institutions – political, judicial, or administrative systems – that allow disputes to be resolved without resorting to violence. When these institutions become weak, biased, or unable to guarantee agreements made, rivalries can degenerate into confrontation. The collapse of the Somali state in the early 1990s illustrates this phenomenon. After the fall of Siad Barre’s regime in 1991, rivalries between clans turn into armed conflicts, in a context where no recognized authority can impose or guarantee a lasting compromise.
At the heart of these dynamics is always the same question: who wins and who pays for the war? When certain actors can capture the benefits of the conflict – political power, control of resources, or economic rents – while externalizing its costs onto the population, escalation becomes more likely. The case of the Falklands War illustrates this example: a junta facing internal challenges and thinking that starting a conflict would provide a solution to their situation.
In this perspective, and as demonstrated by Blattman, war emerges when compromise becomes impracticable. This moment generally corresponds to the gradual collapse of the mechanisms that allow opponents to negotiate rather than fight. The European crisis of 1914 illustrates this mechanism: after the assassination of Archduke Franz Ferdinand, several mediation attempts fail and military mobilizations succeed each other, gradually reducing the space for compromise.
An article-subtitle: “The biological dimension and group dynamics”
In addition to economic and institutional factors, war is rooted in deeply human dynamics. Research from anthropology and evolutionary psychology, including Mike Martin’s analysis, emphasizes the central role of status, belonging, and leadership in collective violent behaviors.
Human societies are structured around hierarchies and prestige logics. Leaders can mobilize these dynamics to consolidate their position or strengthen group cohesion against an external enemy. From this perspective, war can be seen as a mechanism for consolidating power or restoring collective status.
Group dynamics also play a determining role. Individuals tend to favor their group membership – a well-documented phenomenon in social psychology. This polarization of “us” and “them” can transform material rivalries into identity conflicts.
An article-subtitle: “The Road to War moment”
In addition to the cited factors, four elements potentially aggravate the situation and facilitate the shift to war.
Strategic uncertainty is a first factor. Actors may misjudge the intentions or capabilities of their adversaries and believe that it is necessary to go to war or that the other party will do so. The Yom Kippur War in 1973 shows how strategic uncertainty can trigger war: Israel underestimates Egyptian and Syrian intentions, misinterprets several warning signals, and is surprised by an offensive that its decision-makers deemed unlikely.
Credibility issues of each stakeholder’s commitments also play a central role. If an agreement cannot be guaranteed over time – especially when the balance of power changes – actors may prefer to fight immediately to avoid a situation of weakness in the future. The most well-known example here is the Russo-Japanese War of 1904, which illustrates the problem of credibility of commitments: Japan fears that Russia will gradually strengthen its position in Manchuria to the point where any future compromise would be meaningless, prompting Tokyo to prefer immediate war to negotiations without guarantees.
Perception errors also reinforce these dynamics: overestimation of one’s own strengths, underestimation of the adversary, or spirals of mistrust. In summary, the shift to war occurs when actors have a poor understanding of their probability of winning (at least one of the two). Deceptive tactics aimed at hiding capabilities or intentions complicate strategic reading and can push towards triggering a conflict.
Lastly, immaterial incentives such as honor, humiliation, revenge, or sanctification of the conflict can turn a confrontation into an existential conflict. The crisis of 1914 illustrates, for example, how national honor can lock diplomatic options: for Vienna as well as for St. Petersburg, backing down would have meant losing face, contributing to transforming a regional crisis into a general war.
An article-subtitle: “Reading conflict trajectories”
Understanding war thus involves less identifying a single cause than observing the trajectories that lead to the breakdown of compromise.
This understanding is not only a matter of historical analysis. It can also contribute to conflict prevention. Identifying warning signals – rising inequalities between groups, lasting political exclusion, weakening institutions, or radicalization of identity narratives – sometimes allows interventions before the mechanisms of violence become irreversible.
This is precisely the goal of early warning systems developed by many international organizations. These systems seek to detect weak signals of escalation – political tensions, institutional degradation, social polarization, or progressive militarization of rivalries – to allow diplomatic or political interventions before the conflict erupts.
