Violence is defined as "the use of physical force so as to injure, abuse, damage, or destroy."1 Less conventional definitions are also used, such as the World Health Organization's definition of violence as "the intentional use of physical force or power, threatened or actual, against oneself, another person, or against a group or community, which either results in or has a high likelihood of resulting in injury, death, psychological harm, maldevelopment, or deprivation."2

Violence often has lifelong consequences for physical and mental health and social functioning and can slow economic and social development.

Violence in many forms can be preventable. There is a strong relationship between levels of violence and modifiable factors in a country such as poverty, income and gender inequality, the harmful use of alcohol and drugs, and the absence of safe, stable, and nurturing relationships between children and parents in the family. Strategies addressing these underlying causes of violence can be relatively effective in prevention.


Scholars are divided on the origins of organized, large-scale, militaristic, or regular human-on-human violence - in other words, war-like behavior:

There are basically two schools of thought on this issue. One holds that warfare… goes back at least to the time of the first thoroughly modern humans and even before then to the primate ancestors of the hominid lineage. The second position on the origins of warfare sees war as much less common in the cultural and biological evolution of humans. Here, warfare is a latecomer on the cultural horizon, only arising in very specific material circumstances and being quite rare in human history until the development of agriculture in the past 10,000 years.3

The idea of the peaceful pre-history and non-violent tribal societies gained popularity with the post-colonial perspective. The trend, starting in archaeology and spreading to anthropology, reached its height in the late half of the twentieth century. This latecomer view of warfare, espoused by Jared Diamond in his books Guns, Germs and Steel and The Third Chimpanzee, posits that the rise of large-scale warfare is the result of advances in technology and city-states. For instance, the rise of agriculture provided a significant increase in the number of individuals that a region could sustain over hunter-gatherer societies, allowing for division of labor and the development of specialized classes such as soldiers, or weapons manufacturers.

Others argue that violence within and among groups is not a recent phenomenon but is a behavior that is found throughout human history:

Human violence is an inescapable aspect of our society and culture. As the archaeological record clearly shows, this has always been true.4

Religious texts support this view, describing the murder taking place in the first family of our human ancestors, when Cain killed his brother Abel (Genesis 4:8).

Violence has been documented in the Holocene, an epoch that began about 11,500 years ago.5 Lawrence H. Keeley in War Before Civilization writes that 87 percent of tribal societies were at war more than once per year, and that 65 percent of them were fighting continuously. He argues that the "primitive" warfare of these small groups or tribes was driven by the basic need for sustenance.6 The attrition rate of numerous close-quarter clashes, which characterize such endemic warfare, produces casualty rates of up to 60 percent.7

Douglas Fry, however, has argued that such sources erroneously focus on the ethnography of hunters and gatherers in the present, whose culture and values have been infiltrated externally by modern civilization, rather than the actual archaeological record spanning some two million years of human existence. He claims that all contemporary tribal societies, "by the very fact of having been described and published by anthropologists, have been irrevocably impacted by history and modern colonial nation states" and that "many have been affected by state societies for at least 5000 years."3

A third position, posited by Steven Pinker in his 2011 book, The Better Angels of Our Nature, roused both acclaim and controversy by asserting that modern society is less violent than in periods of the past, whether on the short scale of decades or long scale of centuries or millennia. He argued that by every possible measure, every type of violence has drastically decreased since ancient and medieval times. A few centuries ago, for example, genocide was a standard practice in all kinds of warfare and was so common that historians did not even bother to mention it. According to Pinker, rape, murder, warfare, and animal cruelty have all seen drastic declines in the twentieth century.8 However, Pinker's analyses have met with much criticism.910


Deaths due to self-harm and interpersonal violence resulted in about 1.34 million deaths in 2010, up from about 1 million in 1990, while deaths due to collective violence decreased from 64,000 in 1990 to 17,700 in 2010.11 By way of comparison, the 1.5 millions deaths a year due to all forms of violence is greater than the number of deaths due to tuberculosis (1.34 million), road traffic injuries (1.21 million), and malaria (830,000), but slightly less than the number of people who died from HIV/AIDS (1.77 million).11

The World Health Organization (WHO) 2014 publication on suicide reported that:

An estimated 804,000 suicide deaths occurred worldwide in 2012, representing an annual global age-standardized suicide rate of 11.4 per 100 000 population (15.0 for males and 8.0 for females). However, since suicide is a sensitive issue, and even illegal in some countries, it is very likely that it is under-reported. In countries with good vital registration data, suicide may often be misclassified as an accident or another cause of death.12

Rates and patterns of violent death vary by country and region. Studies show a strong, inverse relationship between homicide rates and both economic development and economic equality. Poorer countries, especially those with large gaps between the rich and the poor, tend to have higher rates of homicide than wealthier countries. Homicide rates differ markedly by age and gender: For the 15 to 29 age group, male rates were nearly six times those for female rates; for the remaining age groups, male rates were from two to four times those for females.13

For every death due to violence, there are numerous nonfatal injuries. Beyond deaths and injuries, forms of violence such as child abuse, intimate partner violence, and elder maltreatment are also prevalent. Forms of violence such as child maltreatment and intimate partner violence are highly prevalent. A quarter of all adults report having been physically abused as children; 1 in 5 women and 1 in 13 men report being sexually abused as children.14 A WHO multi-country study found that about 1 in 3 (35 percent) of women worldwide have experienced either physical and/or sexual intimate partner violence or non-partner sexual violence in their lifetime.15

Successive editions of the Global Burden of Armed Violence reveal a continuous drop in the average annual number of violent deaths worldwide: from 540,000 violent deaths for the period 2004-2007 and 526,000 for 2004-2009, to 508,000 for 2007-2012. The average global rate of violent deaths stood at 7.4 persons killed per 100,000 population for the period 2007-2012.16

Although there is a widespread perception that war is the most dangerous form of armed violence in the world, of the 508,000 violent deaths in the period 2007-2012, 70,000 were due to direct conflict, with a large proportion of the latter deaths due to armed conflict in Libya and Syria. In the same period were an annual average of 377,000 intentional homicides, 42,000 unintentional homicides, and 19,000 deaths due to legal interventions. Additionally, lethal violence rates in some countries that are not experiencing armed conflict, notably Honduras and Venezuela, have risen to levels characteristic of countries at war.16

This illustrates the value of accounting for all forms of armed violence rather than an exclusive focus on conflict related violence. Certainly, there are huge variations in the risk of dying from armed conflict at the national and subnational level, and the risk of dying violently in a conflict in specific countries remains extremely high. In Iraq, for example, the direct conflict death rate for 2004-2007 was 65 per 100,000 people per year in Iraq and in Somalia 24 per 100,000 people, with peak rates of 91 per 100,000 in Iraq in 2006 and 74 per 100,000 in Somalia in 2007.17


Beyond deaths and injuries, highly prevalent forms of violence (such as child maltreatment and intimate partner violence) have serious lifelong non-injury health consequences. Victims may engage in high-risk behaviors such as alcohol and substance abuse, and smoking, which in turn can contribute to depression, cardiovascular disorders, cancers, and other diseases resulting in premature death.18

In countries with high levels of violence, economic growth can be slowed down, personal and collective security eroded, and social development impeded. Families edging out of poverty and investing in schooling their sons and daughters can be ruined through the violent death or severe disability of the main breadwinner. For societies, meeting the direct costs of health, criminal justice, and social welfare responses to violence diverts many billions of dollars from more constructive societal spending. The much larger indirect costs of violence due to lost productivity and lost investment in education work together to slow economic development, increase socioeconomic inequality, and erode human and social capital.

Additionally, communities with high levels of violence do not provide the level of stability and predictability vital for a prospering business economy. Individuals will be less likely to invest money and effort towards growth in such unstable and violent conditions.19


Violence has been defined as the use of physical force. However, there are many actions that do not involve physical force which are nonetheless destructive, and can be classified as a type of violence:

For many people,… only physical violence truly qualifies as violence. But, certainly, violence is more than killing people, unless one includes all those words and actions that kill people slowly. The effect of limitation to a “killing fields” perspective is the widespread neglect of many other forms of violence. We must insist that violence also refers to that which is psychologically destructive, that which demeans, damages, or depersonalizes others. In view of these considerations, violence may be defined as follows: any action, verbal or nonverbal, oral or written, physical or psychical, active or passive, public or private, individual or institutional/societal, human or divine, in whatever degree of intensity, that abuses, violates, injures, or kills. Some of the most pervasive and most dangerous forms of violence are those that are often hidden from view (against women and children, especially); just beneath the surface in many of our homes, churches, and communities is abuse enough to freeze the blood. Moreover, many forms of systemic violence often slip past our attention because they are so much a part of the infrastructure of life (e.g., racism, sexism, ageism).20

The World Health Organization divides violence into three broad categories:2

  • self-directed violence
  • interpersonal violence
  • collective violence

This initial categorization differentiates between violence a person inflicts upon himself or herself, violence inflicted by another individual or by a small group of individuals, and violence inflicted by larger groups such as states, organized political groups, militia groups, and terrorist organizations. These three broad categories are each divided further to reflect more specific types of violence, broadening the definition beyond the use of physical force:

  • physical
  • sexual
  • psychological
  • emotional

Self-directed violence

Self-directed violence is subdivided into suicidal behavior and self-abuse. The former includes suicidal thoughts, attempted suicides - also called para suicide or deliberate self-injury in some countries - and completed suicides. Self-abuse, in contrast, includes acts such as self-mutilation.

Collective violence

Massacre of Polish civilians during Nazi occupation of Poland, 1939

Collective violence is subdivided into structural violence and economic violence. Unlike the other two broad categories, the subcategories of collective violence suggest possible motives for violence committed by larger groups of individuals or by states. Collective violence that is committed to advance a particular social agenda includes, for example, crimes of hate committed by organized groups, terrorist acts. and mob violence. Political violence includes war and related violent conflicts, state violence, and similar acts carried out by larger groups. Economic violence includes attacks by larger groups motivated by economic gain - such as attacks carried out with the purpose of disrupting economic activity, denying access to essential services, or creating economic division and fragmentation. Clearly, acts committed by larger groups can have multiple motives.21

This typology, while imperfect and far from being universally accepted, does provide a useful framework for understanding the complex patterns of violence taking place around the world, as well as violence in the everyday lives of individuals, families, and communities.

A United States M8 Greyhound armored car in Paris during World War II


Main article: War

War is a state of prolonged violent large-scale conflict involving two or more groups of people, usually under the auspices of government. It is the most extreme form of collective violence.

War is fought as a means of resolving territorial and other conflicts, as war of aggression to conquer territory or loot resources, in national self-defense or liberation, or to suppress attempts of part of the nation to secede from it. There are also ideological, religious and revolutionary wars.

Since the Industrial Revolution the lethality of modern warfare has grown. World War I casualties were over 40 million and World War II casualties were over 70 million.

Interpersonal violence

Saul attacks David (who had been playing music to help Saul feel better), 1860 woodcut by Julius Schnorr von Karolsfeld

Interpersonal violence is divided into two subcategories: Family and intimate partner violence - that is, violence largely between family members and intimate partners, usually, though not exclusively, taking place in the home. Community violence - violence between individuals who are unrelated, and who may or may not know each other, generally taking place outside the home. The former group includes forms of violence such as child abuse, intimate partner violence and abuse of the elderly. The latter includes youth violence, random acts of violence, rape or sexual assault by strangers, and violence in institutional settings such as schools, workplaces, prisons and nursing homes. When interpersonal violence occurs in families, its psychological consequences can affect parents, children, and their relationship in the short- and long-terms.22

Child maltreatment

Main article: Child abuse

Child maltreatment is the abuse and neglect that occurs to children under 18 years of age. It includes all types of physical and/or emotional ill-treatment, sexual abuse, neglect, negligence and commercial or other child exploitation, which results in actual or potential harm to the child's health, survival, development or dignity in the context of a relationship of responsibility, trust, or power. Exposure to intimate partner violence is also sometimes included as a form of child maltreatment.23

Child maltreatment is a global problem with serious lifelong consequences, which is, however, complex and difficult to study. There are no reliable global estimates for the prevalence of child maltreatment. Data for many countries, especially low- and middle-income countries, are lacking. Current estimates vary widely depending on the country and the method of research used. Approximately 20 percent of women and 5-10 percent of men report being sexually abused as children, while 25-50 percent of all children report being physically abused.24

Consequences of child maltreatment include impaired lifelong physical and mental health, and social and occupational functioning (for example, school, job, and relationship difficulties). These can ultimately slow a country's economic and social development.25

Youth violence

Following the World Health Organization, youth are defined as people between the ages of 10 and 29 years. Youth violence refers to violence occurring between youths, and includes acts that range from bullying and physical fighting, through more severe sexual and physical assault to homicide.2

Different types of youth on youth violence include witnessing or being involved in physical, emotional, and sexual abuse (physical attacks, bullying, rape, and so forth), and violent acts like gang shootings and robberies. According to researchers in 2018, "More than half of children and adolescents living in cities have experienced some form of community violence." The violence "can also all take place under one roof, or in a given community or neighborhood and can happen at the same time or at different stages of life."26 Youth violence has immediate and long term adverse impact whether the individual was the recipient of the violence or a witness to it.27

Youth violence has a serious, often lifelong, impact on a person's psychological and social functioning. Youth violence greatly increases the costs of health, welfare, and criminal justice services; reduces productivity; decreases the value of property; and generally undermines the fabric of society. Youth violence impacts individuals, their families, and society.

Recent research has found that psychological trauma during childhood can change a child's brain.

Trauma is known to physically affect the brain and the body which causes anxiety, rage, and the ability to concentrate. They can also have problems remembering, trusting, and forming relationships.28

Since the brain becomes used to violence it may stay continually in an alert state (similar to being stuck in the fight or flight mode). Youth who are exposed to violence may have emotional, social, and cognitive problems: They may have trouble controlling emotions, paying attention in school, withdraw from friends, or show signs of post-traumatic stress disorder.26

Youth who have experienced violence benefit from having a close relationship with one or more people.28 This is important because the trauma victims need to have people who are safe and trustworthy that they can relate and talk to about their horrible experiences. Some youth do not have adult figures at home or someone they can count on for guidance and comfort. Schools in bad neighborhoods where youth violence is prevalent should assign counselors to each student so that they receive regular guidance. In addition to counseling/therapy sessions and programs, it has been recommended that schools offer mentoring programs where students can interact with adults who can be a positive influence on them. Another way is to create more neighborhood programs to ensure that each child has a positive and stable place to go when school in not in session.

Intimate partner violence

Main articles: Domestic violence and Intimate partner violence

Intimate partner violence refers to behavior in an intimate relationship that causes physical, sexual, or psychological harm, including physical aggression, sexual coercion, psychological abuse, and controlling behaviors.2

Intimate partner and sexual violence have serious short- and long-term physical, mental, sexual, and reproductive health problems for victims and for their children, and lead to high social and economic costs. These include both fatal and non-fatal injuries, depression, and post-traumatic stress disorder, unintended pregnancies, sexually transmitted infections, including HIV.29

Factors associated with the perpetration and experiencing of intimate partner violence are low levels of education, history of violence as a perpetrator, a victim or a witness of parental violence, harmful use of alcohol, attitudes that are accepting of violence, as well as marital discord and dissatisfaction. Factors associated only with perpetration of intimate partner violence are having multiple partners, and antisocial personality disorder.

Sexual violence

Meeting of victims of sexual violence in the Democratic Republic of the Congo.

Sexual violence is any sexual act or attempt to obtain a sexual act by violence or coercion, acts to traffic a person, or acts directed against a person's sexuality, regardless of the relationship to the victim. It includes but is not limited to all forms of rape.2

Sexual violence has serious short- and long-term consequences on physical, mental, sexual, and reproductive health for victims and for their children as described in the section on intimate partner violence. If perpetrated during childhood, sexual violence can lead to increased smoking, drug and alcohol misuse, and risky sexual behaviors in later life. It is also associated with perpetration of violence and being a victim of violence.

Many of the risk factors for sexual violence are the same as for domestic violence. Risk factors specific to sexual violence perpetration include beliefs in family honor and sexual purity, ideologies of male sexual entitlement and weak legal sanctions for sexual violence.

Elder maltreatment

Elder maltreatment is a single or repeated act, or lack of appropriate action, occurring within any relationship where there is an expectation of trust which causes harm or distress to an older person. This type of violence constitutes a violation of human rights and includes physical, sexual, psychological, emotional, financial, and material abuse; abandonment; neglect; and serious loss of dignity and respect.2

Although there is little information regarding the extent of maltreatment in elderly populations, especially in developing countries, abuse of elders by caregivers is a worldwide issue. Older people are often afraid to report cases of maltreatment to family, friends, or to the authorities. Data on the extent of the problem in institutions such as hospitals, nursing homes and other long-term care facilities are scarce. Elder maltreatment can lead to serious physical injuries and long-term psychological consequences.


Violence cannot be attributed to a single factor. Its causes are complex and occur at different levels. To represent this complexity, the ecological, or social ecological model is often used. The following four-level version of the ecological model is often used in the study of violence:

The first level identifies biological and personal factors that influence how individuals behave and increase their likelihood of becoming a victim or perpetrator of violence: demographic characteristics (age, education, income), genetics, brain lesions, personality disorders, substance abuse, and a history of experiencing, witnessing, or engaging in violent behavior.30

The second level focuses on close relationships, such as those with family and friends. In youth violence, for example, having friends who engage in or encourage violence can increase a young person's risk of being a victim or perpetrator of violence. For intimate partner violence, a consistent marker at this level of the model is marital conflict or discord in the relationship. In elder abuse, important factors are stress due to the nature of the past relationship between the abused person and the care giver.

The third level explores the community context: schools, workplaces, and neighborhoods. Risk at this level may be affected by factors such as the existence of a local drug trade, the absence of social networks, and concentrated poverty. All these factors have been shown to be important in several types of violence.

Finally, the fourth level looks at the broad societal factors that help to create a climate in which violence is encouraged or inhibited: the responsiveness of the criminal justice system, social and cultural norms regarding gender roles or parent-child relationships, income inequality, the strength of the social welfare system, the social acceptability of violence, the availability of weapons, the exposure to violence in mass media, and political instability.


Cross-cultural studies have shown that greater prevalence of corporal punishment of children tends to predict higher levels of violence in societies. For instance, analysis of 186 pre-industrial societies found that corporal punishment was more prevalent in societies which also had higher rates of homicide, assault, and war.31 In the United States, domestic corporal punishment has been linked to later violent acts against family members and spouses.32

While studies showing associations between physical punishment of children and later aggression cannot prove that physical punishment causes an increase in aggression, a number of longitudinal studies suggest that the experience of physical punishment has a direct causal effect on later aggressive behaviors.33


The causes of violent behavior in people are often a topic of research in psychology, where "violent behavior is defined as overt and intentional physically aggressive behavior against another person."34

Since violence is a matter of perception as well as a measurable phenomenon, psychologists have found variability in whether people perceive certain physical acts as "violent." For example, in a state where execution is a legalized punishment we do not typically perceive the executioner as "violent," though we may talk, in a more metaphorical way, of the state acting violently. Likewise, understandings of violence are linked to a perceived aggressor-victim relationship: hence psychologists have shown that people may not recognize defensive use of force as violent, even in cases where the amount of force used is significantly greater than in the original aggression.35

Whether violence is an inherent human trait has long been a contentious issue. Certainly, religious texts record violence within the first human family, when Cain killed his brother Abel out of anger and jealousy (Genesis 4:4-8). Among prehistoric humans, there is archaeological evidence for both contentions of violence and peacefulness as primary characteristics.36

The "violent male ape" image is often brought up in discussions of human violence, arguing that violence is inherent in human beings, particularly males, just as it is in non-human primates, although studies have also shown that not all primates are violent.37

Evolutionary psychologists argue that humans have experienced an evolutionary history of violence, being similar to most mammal species and use violence in specific situations. Seven adaptive problems our ancestors recurrently faced have been proposed as being solved by aggression: "co-opting the resources of others, defending against attack, inflicting costs on same-sex rivals, negotiating status and hierarchies, deterring rivals from future aggression, deterring mate from infidelity, and reducing resources expended on genetically unrelated children."38

Today, the use of violence often is a source of pride and a defense of honor, especially among males who believe violence defines manhood.39 Violent behavior may represent an effort to eliminate feelings of shame and humiliation, and gain respect.40

Nevertheless, violent tendencies can be overcome in human society.41 In fact, "we can control our propensity for violence - however deep-rooted it may be - better than other primates can." 42 Again, the biblical record supports such a position, describing how the brothers Jacob and Esau were able to reconcile without violence (Genesis 33:4). In fact, throughout history, most religions, and religious individuals like Mahatma Gandhi, have taught that humans are capable of eliminating individual violence and organizing societies through purely nonviolent means.

Targeted violence

Several rare but painful episodes of assassination, attempted assassination and school shootings at elementary, middle, high schools, as well as colleges and universities in the United States, led to a considerable body of research on ascertainable behaviors of persons who have planned or carried out such attacks. These studies (1995-2002) investigated what the authors called "targeted violence," described the "path to violence" of those who planned or carried out attacks and laid out suggestions for law enforcement and educators. A major point from these research studies is that targeted violence does not just "come out of the blue."43


Research into the media and violence examines whether links between consuming media violence and subsequent aggressive and violent behavior exists. Although some scholars had claimed media violence may increase aggression,44 this view is coming increasingly in doubt both in the scholarly community45 and was rejected by the US Supreme Court in the Brown v EMA case.46