In the fight between good and evil, men more often side with evil than women do.
Whether it is in acts of personal violence such as rape or murder, or group violence such as rioting, gangland murders or war, men play a role far that far exceeds that of women.
Consider the facts.
Men are the major perpetrators of violent crime. Data from the United States for the period 1980 to 2008, for example, shows that men were responsible for 90 percent of the murders committed during that period. 
Men are also the major victims of violent crime. The same U.S. data shows that 77 percent of the murder victims over those same two decades were men.
Women, on the other hand, are more likely to be the victims, rather the perpetrators, of violent crime.
In fact, the degree to which women are the victims of male violence is truly staggering. Women aged 15 to 44 worldwide are more likely to be killed or maimed because of male violence than because of war, cancer, malaria, and traffic accidents combined. 
In the U.S. alone, the number of women murdered as a result of domestic violence between 9/11 and 2012 exceeded the number of terrorist victims on that day and all American soldiers subsequently killed in the War on Terror combined. 
Male violence against women is one of the invisible and under-recognised pandemics of our time.
What is it that makes men more likely to be violent than women?
In seeking explanations, it is important to recognise that violence cannot be explained in terms of a single cause. Instead there are multiple possible factors that contribute to violent behaviour.
One possible factor is biology. Research shows that persistent violent offending is often correlated with minor brain damage or certain psychological abnormalities, particularly psychopathy.
A second possible contributing factor is childhood trauma. There is strong evidence that severe neglect and violent abuse in childhood are high risk factors for violent behaviour in adults. It is abundantly clear that grossly dysfunctional parenting can cause acute problems in child development, which in turn can result in delinquent behaviour, including violence.
A third possible contributory factor is the influence of groups on individual behaviour.
Research into group violence, such as racial and homophobic assaults, has shown that violent groups are typically made up of four different types of offenders: thugs for whom violence is their normal means of resolving disputes; xenophobes who blame others for their own troubles; sympathisers who become involved through peer pressure; and politically motivated offenders, who are usually educated and indulge in violence in pursuit of their political beliefs. 
In organised gang violence, financial rewards from lucrative illegal activities such as drug dealing, human trafficking, and prostitution provide an additional powerful incentive for gang membership. Poverty, high unemployment and lax law enforcement provide the context within which violent gangs can thrive.
A further possible explanation for violent behaviour is given by sociological theories of violence. One such argument is that capitalism encourages egoism and greed, rather than altruism, and provides a supportive culture for violence. Moreover, the argument holds, in capitalist societies the rich are in a position to engage in large scale fraud, or to launch full scale wars for personal gain, secure in the knowledge that they will escape punishment.
Whatever the range of factors contributing to violent behaviour – brain damage, psychopathy, childhood trauma, the influence of groups, or societal context – it is clear that they affect men to a larger degree than women.
This brings us a final possible contributing factor, and one which can have markedly different effects on men and women – gender construction.
Research on gender strongly suggests that many of the differences between men and women that we take for granted, are something we are taught rather than something we are born with.
According to Lise Eliot of Chicago Medical School, for example, infant brains are so malleable that small differences at birth become amplified over time through parental and societal reinforcement of gender stereotypes. Girls, Eliot holds, are not naturally more empathic than boys. They just get to practice these feelings more. 
By age 5 most boys and girls will have internalised the gender roles and expectations taught them by their families, schools, religions and societies. And in many instances, boys will have been socialised for violence – by being taught that being a man means being tough, powerful, intimidating, and a stud.
While constructions of masculinity differ widely both within and between countries, it seems clear that some constructions of masculinity increase the chances of boys growing up to become violent men.
Weighing the Evidence
The evidence so far available suggests two important conclusions.
First, there is no conclusive evidence that men and women differ in their innate biological or psychological propensity for violence. The fact that men commit the majority of violent acts may instead be understood as arising mainly from the social environment.
Second, the fact that explanations of persistent violent behaviour are to be found to varying degrees in brain damage, psychological abnormality, childhood trauma, group peer pressure, and adverse social environments allows us to go one step further and conclude that persistent violent behaviour is an abnormality that emerges under certain circumstances.
Under the patriarchal circumstances that currently prevail world-wide, this abnormality emerges in men to a much greater degree than in women.
What to do?
So what to do? A lot, of course, is already being done. In keeping with the fact that violence has multiple causes, those working on solutions are doing so on multiple fronts.
Four types of peacemaker stand out.
The first are the many groups worldwide working to empower women. Violence against women is most likely when the power differential between men and women is large. Enforcing women’s rights to equality in domestic, economic and political relationships is therefore key to reducing violence.
However, since there is no conclusive evidence that women are inherently less violent than men, empowering women without changing the widespread acceptance of violence in society can only be part of the solution.
Hence three other types of peacemaker are crucial.
First, the forces of law enforcement, whose role is to remove persistent violent offenders from circulating in society and to provide a credible deterrent against violent behaviour.
Second, those working to redefine masculinity so that boys grow up believing that being a man can also mean being gentle, nurturing and empathic.
And third, those opposing violence in all its forms by pressing for non-violent solutions to human conflicts. This group realises that violence traumatises and embitters and its use continually creates ever more violent individuals.
Together these peacemakers are working towards a world in which violence is seen as an abnormality – an abnormality from which both men and women can be equally immune.
- Feminism and Men, Nikki van der Gaag, Zed Books, London, 2014, page 198
- Men Explain Things To Me, Rebecca Solnit, Granta, 2014, page 30
- Men Explain Things To Me, Rebecca Solnit, Granta, 2014, page 23
- Quoted in Understanding Violent Crime, Stephen Jones, Open University Press, 2000, page 73
- Feminism and Men, Nikki van der Gaag, Zed Books, London, 2014, page 62