Professor Kwame Anthony Appiah is a philosopher advocating a school of thought called 'cosmopolitanism'. He describes cosmopolitanism as a very old tradition because the word "cosmopolitan" comes from the Greek phrase from the 4th century BC, 'kosmopolites', which means "citizen of the world". It is a tradition of thought, which tries to develop a metaphor for the idea that we are all citizens of the world, he explains. Cosmopolitans welcome diversity of culture,...