I think RudimentalDrummer was just trying to be civil and polite.
Here are my personal opinions that I'd like to add:
Philosophically speaking, I don't think ANYBODY should be excessively headstrong in their beliefs- anybody who claims absolutely certain that he understands or knows the whole truth about a matter is probably wrong, due to the nature of knowledge itself.
Now, about the caste system. First of all, while I don't feel this is actually relevant- I am an Indian myself, my father is an Indian citizen who is of somewhat agricultural background and my mum is a Singaporean citizen whose grandparents were teachers, I think. I have no idea what my caste is, nor do I give a damn. My ex-girlfriend was a Punjabi girl who's from a Sikh family and her parents very strongly disapproved of our relationship, so I have faced that sort of discrimination within that community.
The CONCEPT of the caste system is pretty solid. The way I understand it, humanity as a whole is like a single human being, with the head/brains, arms/torso, legs, feet, etc. The nice thing about this concept is that it suggests that we all need each other, and that the head (brahmins- teachers, scholars, thinkers) help the arms (government, management, rulers, authorities) understand what they should be doing, and the torso/legs (the general public and masses) support the whole system. Without the head, the arms would do the wrong things, without the arms, nothing can be done, and without the legs, society itself is crippled. It's a beautiful way of looking at how we all contribute to society.
The UGLY part of this? Entitlement mentality, and the absence of meritocracy. Every society has its head, arms and legs- even right here in Singapore. The difference? Our society believes that your position in society should be determined by your actions and your capability. Imagine this- a family of "heads" has been producing great and sound thinkers for generations. Suddenly, however, the children turn out to be mentally retarded. Should they be given the roles of advisors anyway, simply because of birthright?
Similarly, imagine a child from a family of "feet", full of poverty and suffering and vices. He has a thirst for knowledge- whether in-born or nurtured, it doesn't matter. He works hard, pays for his own education, and betters his "head" classmates at intellectual discussion and capacity. Should he be denied the right to lead, simply because of who he was born to?
Such restrictions utterly waste the potential of our humanity. In economic terms, this allows those in power to remain unchecked and inefficient, and it discourages those from poorer backgrounds from realizing their maximum potential because society doesn't choose to recognize them.
Abraham Lincoln was born to uneducated farmers. He would have not been able to make his contributions to mankind if he were forced to remain a farmer.
The Caste system, like Communism, sounds like a perfect system until you implement it on imperfect human beings, who will naturally exploit it to the best of our ability. You only need to look around to see that it is not a very successful system in today's context. Corruption is rampant and progress is limited.
I know I will not be successful in changing Martel's strong beliefs, but please look to common sense and see the caste system for what it really is- a backward system which fulfilled it's purpose of keeping order and stability in the feudal era, but does not belong in modern society today.