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The Psychology of War

Why do humans find it so difficult to live in peace?

Read any book about the history of the World and it’s likely that you’ll be left with one overriding impression: that human beings find it impossible to live in peace with one another. And just when the world appears to be close to another major conflict—the standoff between Russia and Ukraine which has been developing over the last few days—it seems a good time to ponder why this seems to be the case.

Books on world history usually begin with the civilizations of Sumer and Egypt, which arose around 3,000 BC. From that point until the present day, history is little more than a catalog of endless wars. Between 1740 and 1897, there were 230 wars and revolutions in Europe, and during this time countries were almost bankrupting themselves with their military expenditure.

Warfare actually became slightly less frequent during the nineteenth and early twentieth centuries, but this was only because of the awesome technological power nations could now utilize, which meant that wars were over more quickly. In reality, the death toll from wars rose sharply. Whereas only 30 million people died in all the wars between 1740 and 1897, estimates of the number of dead in the First World War range from 5 million to 13 million, and a staggering 50 million people died during the Second World War. (Since then, deaths from warfare have declined significantly, for reasons I will discuss later.)

Theories of Warfare

How can we explain this pathological behavior?

Evolutionary psychologists sometimes suggest that it’s natural for human groups to wage war because we’re made up of selfish genes that demand to be replicated. So it’s natural for us to try to get hold of resources that help us survive, and to fight over them with other groups. Other groups potentially endanger our survival, and so we have to compete and fight with them.

There are also biological attempts to explain war. Men are biologically primed to fight wars because of the large amount of testosterone they contain, since it is widely believed that testosterone is linked to aggression. Violence may also be linked to a low level of serotonin, since there is evidence that when animals are injected with serotonin they become less aggressive.

However, these explanations are highly problematic. For example, they cannot explain the apparent lack of warfare in early human history, or pre-history, and the relative lack of conflict in most traditional hunter-gatherer societies. This is a hotly debated issue, and there are some scholars and scientists who claim that warfare has always existed in human societies.

However, many archaeologists and anthropologists dispute this, and I believe that the evidence is firmly on their side. For example, last year the anthropologists Douglas Fry and Patrik Soderberg published a study of violence in 21 modern hunter-gatherer groups and found that, over the last 200 years, lethal attacks by one group on another were extremely rare. They identified 148 deaths by violence amongst the groups during this period, and found that the great majority were the result of one-on-one conflict, or family feuds. Similarly, the anthropologist R. Brian Ferguson has amassed convincing evidence to show that warfare is only around 10,000 years old, and only became frequent from around 6,000 years ago.

And one problem biological theories of warfare is that, while they might be able to explain specific outbreaks of violence, warfare is actually much more than this. Warfare is a highly planned and organized activity, mostly conducted and organized in non-violent situations — which does not involve a great deal of actual fighting.*

Psychological Explanations

The first psychologist to investigate war was William James, who wrote the seminal essay "The Moral Equivalent of War" in 1910. Here James suggested that warfare was so prevalent because of its positive psychological effects, both on the individual and on society as a whole.

On a social level, war delivers a sense of unity in the face of a collective threat. It binds people together—not just the army engaged in battle, but the whole community. It brings what James referred to as discipline—a sense of cohesion, with communal goals. The "war effort" inspires individual citizens (not just soldiers) to behave honorably and unselfishly in service of a greater good.

On an individual level, one of the positive effects of war is that it makes people feel more alive, alert, and awake. In James’ words, it "redeem[s] life from flat degeneration." It supplies meaning and purpose, transcending the monotony of everyday life. As James puts it, "Life seems cast upon a higher plane of power." Warfare also enables the expression of higher human qualities that often lie dormant in ordinary life, such as discipline, courage, unselfishness, and self-sacrifice.

In my book, Back to Sanity, I emphasize two further important factors. One obvious factor is the drive to increase wealth, status, and power. A major motivation of warfare is the desire of one group of human beings—usually governments, but often the general population of a country, tribe or ethnic group—to increase their power and wealth. The group tries to do this by conquering and subjugating other groups, and by seizing their territory and resources.

Pick almost any war in history and you’ll find some variant of these causes: wars to annex new territory, to colonize new lands, to take control of valuable minerals or oil, to help build an empire to increase prestige and wealth, or to avenge a previous humiliation, which diminished a group’s power, prestige, and wealth. The present conflict in the Ukraine can be partly interpreted in these terms—the result of Russia’s desire to increase its territory and prestige by gaining control of the Crimea, and responding to the prestige-weakening blow of losing its favored government in the Ukraine.

Secondly, war is strongly related to group identity. Human beings, in general, have a strong need for belonging and identity which can easily manifest itself in ethnicism, nationalism, or religious dogmatism. It encourages us to cling to the identity of our ethnic group, country or religion, and to feel a sense of pride in being British, American, White, Black, Christian, Muslim, Protestant or Catholic.

The problem with this isn’t so much having pride in our identity, but the attitude it engenders towards other groups. Identifying exclusively with a particular group automatically creates a sense of rivalry and enmity with other groups. It creates an "in/out group" mentality, which can easily lead to conflict. In fact, most conflicts throughout history have been a clash between two or more different identity groups—the Christians and Muslims in the Crusades, the Jews and Arabs, Hindus and Muslims in India, the Catholics and Protestants in Northern Ireland, the Israelis and Palestinians, the Serbs, Croats, and Bosnians, and so on.

Again, the present conflict in Ukraine is easily interpreted in these terms. The dispute over Crimea lies in the fact that most of the region’s population identify themselves as ethnically Russian, while the ethnic Ukrainians wish to preserve their own independent identity, away from Russian influence.

The issue of empathy is important here too. One of the most dangerous aspects of group identity is what psychologists call moral exclusion. This happens when we withdraw moral and human rights to other groups and deny them respect and justice. Moral standards are only applied to members of our own group. We exclude members of other groups from our moral community, and it becomes all too easy for us to exploit, oppress, and even kill them.

The Decline of Warfare

The good news is that since the end of the Second World War — as Steven Pinker points out in The Better Angels of Our Nature — there has been a steady worldwide decline in the number of deaths due to warfare. In Europe, countries that had been in an almost constant state of war with one or more of their neighbors for centuries — such as France, Germany, Great Britain, Spain, Holland, Poland, Russia — have experienced an unprecedentedly long period of peace.

As Pinker points out, the decades after the Second World War — up till the 1980s — saw an increase in intrastate violence in the world as a whole, due to a large number of civil wars. But since the 1980s, intrastate violence has declined too, so that the last 25-30 years have been by far the least war-afflicted in recent history, and we've seen a correspondingly low number of casualties.

There are a number of obvious factors responsible for this increased peacefulness — for example, the nuclear deterrent, the growth of democracy (making it more difficult for governments to declare war against the will of their citizens), the work of international peacekeeping forces, and the demise of the Communist Bloc.

Strange as it may sound at first, perhaps sport is a factor too. Sport is a good example of what William James meant by a moral equivalent of war — an activity that satisfies similar psychological needs to war, and has a similar invigorating and socially-binding effect, but does not involve the same degree of violence and devastation. Perhaps it is not a coincidence that, over the 75 years of this steady decline in conflict, sport has grown correspondingly in popularity.

Another important factor is interconnection, increased contact between people of different nations due to higher levels of international trade and travel and (most recently) via the Internet. It is likely that this increased interconnection leads to a decline in group identity, and in enmity towards other groups. It promotes moral inclusion, an expansion of empathy, and makes it less possible for us to perceive different groups as ‘other’ to us. It helps us to sense that, even if they appear culturally or racially different, all human beings are essentially the same as us. I’m certainly not an apologist for globlization, but this is one way (possibly the only way) in which it has had a positive effect.

Perhaps, then, as a species, we are slowly beginning to transcend the pathology of warfare. Hopefully conflicts such as the present one in Ukraine will be seen more and more as aberrations, as group identity fades further and a sense of moral inclusion increases. And perhaps eventually, if this process continues, the need for social identity will fade away to the point that empathy extends indiscriminately, to and from all human beings, so that it becomes impossible — even for power-greedy governments — to exploit or oppress other groups in service of their own desires.

*There are also environmental explanations for war — such as population pressure — which unfortunately I don’t have space to discuss here. See my book The Fall for a fuller discussion.

Steve Taylor, Ph.D. is a senior lecturer in psychology at Leeds Metropolitan University, UK. He is the author of The Fall: The Insanity of the Ego in Human History and Back to Sanity.


Fry, D. P., & Söderberg, P. (19.07.2013). Lethal Aggression in Mobile Forager Bands and Implications for the Origins of War. Science (2013), 341: 270-273.

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