Violence is the exertion of force so as to injure or abuse. The word is used broadly to describe the destructive action of natural phenomena like storms and earthquakes. More frequently the word describes forceful and intentional injury to people, and verbal and emotional abuse towards others. Warfare is large-scale organized violence carried out by one state against another, although states attempt to control violent crime by the rule of law. The causes of violent attitudes and behavior are important topics of study in psychology and sociology.

Psychology and sociology

The causes of violent behavior in humans are often topics of research in psychology and sociology. Neurobiologist Jan Volavka emphasizes that for those purposes, “violent behavior is defined as overt and intentional physically aggressive behavior against another person."

Scientists disagree on whether violence is inherent in humans. Among prehistoric humans, there is archaeological evidence for both contentions of violence and peacefulness as primary characteristics.

Riane Eisler, who describes early matriarchal societies, and Walter Wink, who coined the phrase “the myth of redemptive violence,” suggest that human violence, especially as organized in groups, is a phenomenon of the last five to ten thousand years.

The “violent male ape” image is often brought up in discussions of human violence. Dale Peterson and Richard Wrangham in “Demonic Males: Apes and the Origins of Human Violence” write that violence is inherent in humans. However, William L. Ury, editor of a book called "Must We Fight? From the Battlefield to the Schoolyard--A New Perspective on Violent Conflict and Its Prevention” debunks the "killer ape" myth in his book which brings together discussions from two Harvard Law School symposiums. The conclusion is that “we also have lots of natural mechanisms for cooperation, to keep conflict in check, to channel aggression, and to overcome conflict. These are just as natural to us as the aggressive tendencies."

James Gilligan writes violence is often pursued as an antidote to shame or humiliation. The use of violence often is a source of pride and a defence of honor, especially among males who often believe violence defines manhood.

Stephen Pinker in a New Republic article “The History of Violence” offers evidence that on the average the amount and cruelty of violence to humans and animals has decreased over the last few centuries.

Diagnosis of psychiatric disorder

The American Psychiatric Association planning and research committees for the forthcoming DSM-V (2012) have canvassed a series of new Relational disorders which include Marital Conflict Disorder Without Violence or Marital Abuse Disorder (Marital Conflict Disorder With Violence). Couples with marital disorders sometimes come to clinical attention because the couple recognize long-standing dissatisfaction with their marriage and come to the clinician on their own initiative or are referred by an astute health care professional. Secondly, there is serious violence in the marriage which is -"usually the husband battering the wife" . In these cases the emergency room or a legal authority often is the first to notify the clinician. Most importantly, marital violence "is a major risk factor for serious injury and even death and women in violent marriages are at much greater risk of being seriously injured or killed (National Advisory Council on Violence Against Women 2000)."First, M.B., Bell, C.C., Cuthbert, B., Krystal, J.H., Malison, R., Offord, D.R., Riess, D., Shea, T., Widiger, T., Wisner, K.L., Personality Disorders and Relational Disorders, p.166, Chapter 4 of Kupfer, D.J., First, M.B., & Regier, D.A. A Research Agenda For DSM-V. Published by American Psychiatric Association (2002) The authors of this study add that "There is current considerable controversy over whether male-to-female marital violence is best regarded as a reflection of male psychopathology and control or whether there is an empirical base and clinical utility for conceptualizing these patterns as relational."