Dr. Igor Galynker, director of the Family Center for Bipolar Disorder at Beth Israel Medical Center in New York, noted that almost-psychopathic tendencies can come in handy for a large number of people in certain situations. A soldier on the battlefield or a corporation's CEO wouldn't do very well if they are unable to make decisions that might harm others. But knowing how to deal with people who do this all the time is important.
"You just need to be aware when you meet these people that they will do what is best for them but not necessarily what's best for you," he said.
The authors said their intention is not to attach labels or psychological diagnoses, but to help people who might be struggling with a difficult, hurtful person in their lives.
Author Silver said, "You're not going to be able to change an almost-psychopath. But the idea is to keep track of their behavior, so that it informs you on how you want to interact with or disengage with these people."
Lanning, formerly of the FBI, said being able to recognize almost-psychopaths will help you protect yourself.
"If you don't understand these psychopathic types," he said, "you'll be easily conned by them."