Good and bad are artificial constructs. Nature does not recognize good and bad. We are what we are, products of evolution and our environment. When we started living in larger groups, and because, unlike other animals, we were capable of thought and deliberate actions, we had to invent the concept of good and bad in order to separate behaviour that would benefit the group from that which would harm the group.

The definition of good and bad behaviour has evolved through time. Three hundred years ago a good man might be one who regularly beat his slaves to keep them in line. As well, every person’s behaviour changes according to circumstances and influences many times during his life.

In movies and the public imagination, masses of people caught in a deadly crisis will stampede, kill, and rob in a panicked attempt to save themselves. But on 911 people helped each other down eighty flights of smoke filled stairs in the dark. People outside walked and ran away from the falling buildings together and anyone who stumbled was picked up by those behind. When dazed and choking survivors made it on foot to Harlem they were met by residents offering glasses of ice water.

On the other hand, people have formed lynch mobs, gang raped, murdered because of skin colour, fire bombed schools, carpet bombed cities, tried to exterminate entire races.

People are capable of both extreme good and extreme bad as we define those terms. Most people, I believe, see themselves as good when they are doing good and justified when they are doing bad. I doubt that many people, even the worst criminals, really think of them selves as bad.

By any modern definition of good and bad, we have gotten a lot better throughout the history of our species. In the days when we were hunter gatherers, a person had a better than 50% chance of dying by homicide.

For a very informative and interesting book on the subject, try The Better Angels of Our Nature: Why Violence Has Declined by Steven Pinker.