Bollywood’s biggest star has an answer ready if census workers ask about his caste: “Indian.”

“My father never believed in caste, and neither do any of us,” Amitabh Bachchan wrote in his obsessively followed blog.

Comments like Bachchan’s are common in modern India, which prides itself on how it has transcended some of its most rigid traditions — and those beliefs are being heard more often as the government debates whether the national census should delve into caste.

But Joseph D’Souza doesn’t believe such talk for a moment.

“There’s a lot of lip service to saying ‘I’m an Indian first,’ and ‘I don’t believe in caste,'” said D’Souza, a prominent campaigner for dalits, as India’s “untouchables” at the very bottom of the caste system are now known.

“When it comes to sharing power, to interaction, to sharing social status, low-caste Indians are very much marginalized,” he said, arguing the census could provide firm data about the vast divisions.

India’s census, being held in stages over the next year or so, delves into the wealth, living conditions and other personal details of the country’s 1.2 billion people. But still undecided is one question — “What is your caste?” — that has infuriated much of India’s elite, energized caste-based political parties and left in doubt millions of government jobs and university slots.

The debate has also made very clear that caste, the Hindu custom that for millennia has divided people in a strict social hierarchy based on their family’s traditional livelihood and ethnicity, remains a deeply sensitive subject.

“The biggest issue (with the census) is the inability of India to come to terms with this really ingenious form of discrimination,” D’Souza said.

Bachchan, who has dominated Bollywood for decades, proudly says his family has married across India’s vast geographic spectrum — with a Bengali, a Sindhi, a Punjabi and a Mangalorean. But D’Souza notes that none of those relatives are low caste and that the movie industry has not one dalit star.

The question’s fiercest backers include India’s most powerful caste politicians, who believe they could use the census data as fodder for votes and government funding.

Its bitterest opponents include much of the establishment. “At one stroke, it trivializes all that modern India has stood for, and condemns it to the tyranny of an insidious kind of identity politics,” Pratap Bhanu Mehta, a prominent Indian commentator, wrote in the Indian Express newspaper.

The last Indian census that measured castes was in 1931, when colonial Britain still ruled.

The founders of modern India — nearly all high caste — were, at least publicly, staunch believers in a caste-blind society. While many would have been aghast if one of their children had married a dalit, they also fought hard for dalit rights.

Most felt that counting caste sizes in a census reinforced a tradition they wanted to fade.

It’s an argument still heard today.

“No one denies that there are a lot of problems in India, that there is social discrimination,” said Barun Mitra, who runs a New Delhi-based research center. But “this process of identifying caste with a census is unlikely to help.”

Like many critics, he also worries about the rise of the caste-based politicians.

“What purpose would it serve by drawing and redrawing the identity one more time, particularly when it is politically motivated?” he asked.

In recent decades, some of the sharpest edges of caste traditions have been softened by urbanization and economic growth. Inter-caste marriages are now fairly common, and there are powerful low-caste politicians and businesspeople.

But caste also remains a deeply felt part of Indian life. Brahmins, the highest caste, still dominate everything from politics to journalism. Caste-specific marriage advertisements are newspaper staples. Studies show low-caste Indians and dalits face daily challenges for decent schools, medical care and jobs.

“Caste is part of every social agenda, every political agenda,” said Shaibal Gupta with the Asian Development Research Institute. “Even when someone is considering a neighborhood, caste is an important consideration.”

But caste calculations have become far more complicated, with jobs and university slots reserved for lower castes and a new generation of politicians learning to use their lower-caste backgrounds to create massive vote banks.

Laws give specific breakdowns of those reserved positions, but since the numbers are based on the 1931 census, their accuracy is questioned. And protests have been violent as caste leaders try to have their group’s status officially lowered to be eligible for reserved jobs and school slots.

For some opponents, complexity alone makes caste an impossible census question. While there are just four main castes, there may be more than 20,000 sub-castes. Then there are the sub-sub-castes, clans and a multitude of other variations.

But for proponents like D’Souza, such arguments prove the necessity of the question. In a country where caste is so important, he asks, how can India not know the facts?

“You can’t hide it and put it under the carpet and say caste is not there,” he said.