Answer by Makarand Sahasrabuddhe:
It is always dangerous to evaluate what happened in the past with the social values of today.
Most of the criticism of the caste system that we see in the present or the recent past comes from using relatively modern lenses of equality and equity for all humans.
For centuries humans genuinely did not believe that everyone was equal. This is not only in India but true all over the world as can be evidenced by
- secondary status of women almost everywhere in the world.
- inter-tribal conflicts in Africa which are about superiority and not only about economic issues.
- the upper-class / serfs systems in Japan and in Europe.
- slavery in Egypt, the Middle-East and almost all parts of the world.
Different societies ascribed different reasons for superiority of one section of people over others. Some of these reasons are laughable and / or pitiable when discussed and analysed today. At that time they were merely a fact of life just as a 'flat-earth' or 'geo-centric universe' was a fact of life.
The reason that older Indian philosophers did not declaim the caste system is that they were part of the same system and they probably took some of the under-pinning concepts to be axiomatic. It requires one to be a very rare genius to be centuries (even decades actually) ahead of time and envision something that has not existed – equality for instance.
Some of the more modern Indian philosophers likeand have spoken about the evils of caste system but then they lived in relatively modern times where it was silly to believe that the 4 castes were created differently by .
Go a little easy on the Indian philosophers – they, like many others from the West and East were trapped by their times.