“They begin by reviewing a definition of “disorder” that the Canadian researchers cited having to do with “the failure of an internal mechanism to perform a natural function for which it was designed” leading to harmful consequences.” Giving as an example psychopaths’ impaired processing of fear and distress cues from others that would otherwise lead them to restrain their behavior, they argue that psychopaths do meet the first part of the definition. And they point out that even the Canadian authors agree that psychopathy does lead to harm to individuals and society. Thus, they maintain that psychopathy does meet the criteria to be considered a mental disorder.”

This assumes a “failure of an internal mechanism to perform a natural function for which it was designed”. This does not consider that what the writer considers a failure of an internal mechanism may very well be BY DESIGN.

Imagine for a second.. that these ‘harmful consequences’ are purposeful if viewed from a different perspective. A controlled or restrained fear or distress may actually BE the purpose… depending on the environment that has contributed to this evolution.