You could try a statistical approach, for instance. If someone’s behavior is statistically rare, then that behavior is abnormal. But lots of people have behavior that is statistically rare. For instance, I went to the Minnesota Renaissance Festival just yesterday, and enjoyed some good people-watching. The Ren Fest has a variety of people – some are just pop-culture “nerds.” Some are people who love cosplay (where you dress up as a character – either made up by you or pre-created in popular culture – and act as if you are that person). And some people honestly believe they are wizards. Should we consider any of these statistically rare behaviors due to mental illness? Well, perhaps people who really believe they are wizards, but some of those people are pagans – and should we consider people of a rare religion to be mentally ill per se? 

You could also try a societal norm approach. If someone behaves outside the behavioral norm, then they are abnormal. But this, in itself does not imply mental illness. Societal norms can change from culture to culture. As an example, in some tribal cultures, the men cut themselves over and over again to “beautify” themselves with scars; but in America teens who cut are generally diagnosed with depression. Norms can also change within one culture over time. For instance, a couple decades ago homosexuality was considered a mental illness, but now it is, for the most part, accepted as “normal” behavior for certain individuals. 

There is also the maladaptive approach. If someone’s behavior is injurious to himself or to society, then he is abnormal. A person with OCD who washes her hands so much that they are cracked and bleeding is maladaptive. But this approach is not full-proof either. Not everyone who commits a crime is mentally ill. Likewise, should we consider someone who donates bone marrow, blood, or a kidney mentally ill?

Many people who are mentally ill suffer. But not all. The mania state of bipolar disorder is often pleasant to the patient, but he is considered mentally ill. Also, where do we draw the line of diagnosing mental illness for those who are suffering? If someone has just lost her home or a loved one, she is suffering from grief. But isn’t grief a natural and healthy response, within limits? 

Another approach is irrationality and unpredictability, but teenagers and young adults often do irrational and unpredictable things for attention or just because they’re trying to impress a girl. Mental illness? Nah. 

The last approach I will discuss is dangerous behavior. But yet again, that is not always indicative of mental illness. Many people jump out of planes, bungee jump, or fight in a war. These people are not considered “abnormal.” 

The DSM-5 defines mental disorder as: 

“a syndrome characterized by clinically significant disturbance in an individual’s cognition, emotion regulation, or behavior that reflects a dysfunction in the psychological, biological, or developmental processes underlying mental functioning. Mental disorders are usually associated with significant distress in social, occupational, or other important activities. An expectable or culturally approved response to a common stressor or loss, such as the death of a loved one, is not a mental disorder. Socially deviant behavior (e.g., political, religious, or sexual) and conflicts that are primarily between the individual and society are not mental disorders unless the deviance or conflict results from a dysfunction in the individual, as described above.”

What the heck does that mean? 

In the end, mental illness diagnoses are subjective to the clinician. For instance, I was diagnosed with bipolar disorder II. This means that I experience abnormal highs and lows (as well as other traits). I totally agree with this diagnosis. But another psychiatrist diagnosed me with borderline personality disorder. “What?!” I said. I don’t have an intense fear of abandonment, a pattern of intense interpersonal relationships characterized by alternating states of idealization and devaluation, paranoid ideation, or disassociative symptoms. Granted, I have more than 5 other traits, which makes me diagnosable with borderline. But all of those symptoms are traits that can be explained by bipolar disorder. So why the boderline personality disorder diagnosis?

What do you think? How would you define “abnormal”?