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¶ … causes of violence, John Monahan details the limited knowledge and research that currently exists. He argues that, although biological, sociological, and psychological factors contribute individually to causing violence, the root of the problem lies in a combination of all three. In attempting to develop a multi-causal explanation, Monahan points to the influence and role of the family.

Although many theories have emphasized the importance of biological factors, such as hormones, chemical imbalances, brain injury, and genetics, in the causation of violence, the present level of scientific research has failed to identify any definite links. However, this same research has also failed to categorically disprove biological factors as a potential cause, thus supporting Monahan's call for an increase in the funding of study and research in this area.

The most commonly cited causes of violence are the many, and varied sociological factors. Although social science has been able to build an extensive database of studies and research within this topic, the huge range of factors and their potential interdependence make it difficult for concrete, isolated conclusions to be reached. Factors such as poverty; unemployment; gender; age; education; race; and geography have all been identified as potential causes of violence. However, they very rarely occur in isolation. Monahan's describes this problem as the 'ball of wax' effect, in which several of these factors relate not only to an increased propensity for violent behavior but also to each other. Therefore, although poor, unemployed, African-American males are statistically more likely to be arrested for participation in violent crimes than other social groups, it is impossible to accurately identify whether this results from the singular factors of race, poverty, or unemployment or, as is becoming increasingly accepted, a combination of all these factors. Another difficulty, and one that Monahan only partially highlights within his synopsis, is degree to which research is reliant upon official statistics. A great deal of the data on violent crime is based, not on the total number of violent incidents, but on arrest rates, which may lead to inaccuracies due to deliberate or unintentional discrimination, and selective data.

The third causal model to be highlighted by Monahan is that of psychological factors. As the author emphatically points out, this does not allude to mental disorders, but to the universal developmental processes and stages that occur during the human lifespan. The likelihood of any individual progressing through these psychological stages successfully, without participating in violent behavior, is, according to Monahan, closely associated with the 'family'.