Once again we are all caught up in an incident of seemingly senseless violence. This time it is right in the middle of the highly charged political debate and protest over police violence. There is much focus on the mental condition of Ismaaiyl Abdula Brinsley who killed two police officers seemingly selected at random. He apparently has a history of "mental instability". As with other cases of relatively indiscriminate violence many people want to say that a mental illness was the CAUSE of the violence. That is something of a platitude that is easy to accept because it is a horrible event for which we have no other logical explanation. However, there is not a lot of scientific evidence to base that on.
There is a Latin phrase that is very useful for discussing this issue. Post hoc, ergo proptor hoc. This refers to the assumption that because event A occurs prior in time to the occurrence of event B, therefore event A is the cause of event B. The mere sequence of events in time is not adequate proof of cause and effect.
I have diabetes. I am very definitely a non-violent person. Most people would not expect there to be any connection between these two aspects of my being. Yet with a quick Google I found this case of a man with diabetes who was convicted of a multiple murder. Did his diabetes cause his violence? Probably not and most people don't need to be convinced of that.
It is estimated that about 40% of the US population has some form of mental illness. Much of that is anxiety and depression. There is a much smaller number of people with major psychotic disorders, something less than 5%. The vast majority of people with a diagnosed mental illness do not commit acts of violence. They do face challenges and difficulties in their daily lives that are related to their medical problem, but they are not violent. So if we are not ready to attribute other medical problems as the definite cause of violent behavior, why are most people willing to equate it with mental illness?
Every society has forms of sanctioned "legitimate" violence. Responding to what appears to be an obvious threat to your own life in one of them. Police and military are legally authorized to use violence under certain conditions. We seldom attribute those forms of violence to mental illness, even when we consider a specific instance of it to have been unreasonable. There are of course people who enlist in various revolutionary causes and are prepared to use violence which may also result in their own death. They don't have state legitimacy, but we generally tend to think of them as ideologically misguided rather than mentally ill.
Mental illness seems to be a convenient label to pin on violent behavior for which we don't have a readily available pigeon hole. I worked in the field of mental health for a number of years and I know from experience that trying to communicate with people with major mental disorders can sometimes be stressful and confusing. It is understandable that such characteristics make many people reluctant to interact with them if they are in an acute state. However, equating that with dangerous and violent behavior doesn't stand up to reality in most instances.
Thoughts of persecution are a feature that the popular imagination often latches onto. Such thoughts are not entirely unique to people with psychotic disorders, it becomes clinically significant as a matter of degree and how it is situated in a reality context. Most of the people who do exhibit such thoughts in a fairly extreme form never actually go out and act on them in the form of violent behavior. Their existence alone is not sufficient reason to predict violence. So the notion of people with mental illness as a group that poses a significant threat to the world around them is pretty much a popular myth.
There is always the call that wee need to increase the budgets for mental health care to prevent violence. I would certainly would support improved mental health services because there are a lot of people who could be helped by it that aren't getting it. However, I doubt that would do much to prevent violence. The ability of psychologists and psychiatrists to accurately predict who will in fact commit acts of violence is very limited and generally not very reliable. There is also the legal problem of what to do with someone who could become violent but hasn't done anything to break the law. Preventive detention and prior restraint face serious legal hurtles.
People have long seen other people who exhibit what they consider to be strange behavior as a threat. At various time they have been seen as being possessed by evil spirits. We have made some progress in our understanding of such problems and have some forms of useful treatment available. However, we do have fixes and cures. I doubt that mental health has much prospect of coming up with a solution to the problem of violence since it's very meaning is embedded in the structure of society. Violence only becomes a problem when it takes a form that the society doesn't tolerate. We often lack consensus as to just where that line lies.
