How do moral revolutions occur? How, in today's world, can a universal moral stand bring an end to brutal and questionable social customs, such as honour killings and child marriages?
In trying to provide answers to these questions, Prof. Kwame Anthony Appiah who teaches philosophy at Princeton University explains how cruel and inhumane acts that once qualified as custom (such as slavery), collapsed when they were put under moral scrutiny.
When Appiah was conducting research for his book on the subject, he discovered that people don't stop practising something when they realise that it is wrong. "What is interesting is that people almost always sense that something is wrong with a particular practise, long before they start to do something about it," he says.
The shift from recognition of wrongdoing to actually doing something about it comes when people begin to see that they have a stake in change. And that stake often has to do with having a stake in honour.
The Atlantic slave trade largely came to an end because the British working class saw slavery as equating labour with dishonour.
What the Atlantic slave trade did was to take Africans and make them perform manual labour. But that implied that there was something dishonourable about manual labour, and as the British working class was developing a positive identity, they couldn't think of manual labour as dishonourable because "labour" was what defined them.
So by the mid 19th century, even though there were no slaves in Britain, huge numbers of people turned against slavery. More people petitioned against slavery in the early 19th century than on any other issue.
However, while the barbarism of legalised slavery has ended, presently, the brutal custom of honour killings claims the lives of thousands of women a year.
It is difficult to end the practise, argues Appiah, because it is something that deals with family and intimate life. Honour killings are about family honour, which is one of the reasons its hard for outsiders to intervene.
According to Appiah, the places where honour killings are coming to an end are places where people are starting to see that it does not actually do much good for their honour to kill the women in their families.
A world in which contempt for women is something authorised and normalised will lead to a world where women are treated worse, notes Appiah.
Editor's Note: You might also be interested in this article written by Robert Fisk, 'Honor' Killing: The Crimewave that Shames the World -- "It's one of the last great taboos: the murder of at least 20,000 women a year in the name of 'honour'. Nor is the problem confined to the Middle East: the contagion is spreading rapidly."