Clinically, arrogance is often associated with narcissistic personality disorder.
Narcissistic personality disorder is one of a group of conditions called dramatic personality disorders. People with these disorders have intense, unstable emotions, and a distorted self-image. Narcissistic personality disorder is further characterized by an abnormal love of self, an exaggerated sense of superiority and importance, and a preoccupation with success and power. However, these attitudes and behaviors do not reflect true self-confidence. Instead, the attitudes conceal a deep sense of insecurity and a fragile self-esteem. People with this personality disorder also tend to set unrealistic goals.
DSM-IV-TR diagnostic criteria include (reprinted here):
Criteria for narcissistic personality disorder to be diagnosed include:
- Having an exaggerated sense of self-importance
- Being preoccupied with fantasies about success, power or beauty
- Believing that you are special and can associate only with equally special people
- Requiring constant admiration
- Having a sense of entitlement
- Taking advantage of others
- Having an inability to recognize needs and feelings of others
- Being envious of others
- Behaving in an arrogant or haughty manner
From a scientific standpoint, these characteristics can be difficult to pin down, and clinically, NPD is an "Axis II" diagnosis, which means that most insurance (in the United States) won't cover treatment of the disorder in and of itself.
Consequently, the push to discovering its underlying mechanisms may be less strong, but from theory, they are largely believed to be based on environment.
Proponents of the diagnosis are attempting to adjust the diagnostic criteria a bit to make it more objective for the upcoming DSM-V release.