Here's something I scribbled recently
In his book "Identity and Violence" Amartya Sen says that identity is the root cause of conflict. Human being group themselves into different groups, as per their comfort. For eg. we become a part of a certain school/college/institution or a certain society youth group or as a fan of Liverpool or Manchester United. We start associating ourselves not just with religions or professions or nationalities or food habits, but also dressing styles, behavioural styles, and maybe even zodiac signs.
These choices also constitute our identity.
Every individual wants to set himself apart from the others, wants to be unique and starts associating with groups that he identifies with.
The problem arises when people start staunchly following their beliefs. That is when they see themselves as Levi's and not as Wrangler, and then everything about Wrangler seems wrong. Sometimes Wrangler may sound so wrong, that Levi's goes all out to prove a point against him, and in extreme cases it may lead to violence.
Wrangler may not have been right or wrong, but the fact that he choses to be wrangler and separate himself from Levi's is irritating to Levi's. Levi's forgets that he is a son, a brother, a Hindu, an Indian, an IT professional, a cricket fan and in that instance choses only to be Levi's
According to Amartya Sen extremity of associations leads to violence, eg. Nazism, communism, religious fervour and racial influence.