Answer: When you want to defuse a bomb.

That's about it really. And only because psychopaths don't feel fear the way regular folks do. (Of course non-psychopaths defuse bombs too and it's their triumph over fear that we admire so much.)

Why might you need to know more about psychopaths?

For your protection.

About one per cent of the population qualifies as a psychopath. Some extraordinarily talented high-profile people show significant symptoms, as did some evil leaders of the last century.

Let's set aside a couple of myths

All psychopaths are criminals. Some are, but most are law-abiding and productive citizens.

You are either a psychopath, or not. It's a scale and almost everyone is on it. It would be unhealthy and unproductive not to have some symptoms in common with people well up the scale. A leading figure in the research describes the symptoms as like a sound mixer - it's only when most of the sliders are ramped up that you have a problem.

The warning signs

(It's best to leave a full diagnosis to an expert.)

  • Superficial charm
  • Lack of empathy, callousness
  • Grandiose estimation of self
  • Impulsivity
  • Manipulative behaviour, cunning
  • Lack of remorse or guilt
  • Lack of fear
  • Failure to accept responsibilty for own actions

If you are going to appoint or promote someone with just one prominent symptom, check for more. Look behind superficial charm. Know what you are getting into.

These days, success in most jobs takes high levels of honesty, self-control and concern for others' rights and feelings.