In a week when there was the peculiar story of a young woman’s murder three years ago, a massive protest that has killed several people in Gujarat, and the murder of TV journalists on air... how can a column about numbers possibly distract from such tragedies?

Still, I must try. At any other time, something else this week would have been much-discussed news. If overshadowed, it still remains a case study in an ancient truth: the same statistics can support pretty much any hypothesis or prism or stupid idea I choose.

I refer, of course, to data that the Census of India released a few days ago, about the religious composition of this country.

Now, between the 2001 and 2011 censuses, India’s population grew by 17.7%. When it’s religions you’re looking at, there is the obvious question: how much has each faith contributed to that increase? The major contributors are, naturally, our two major religions: Hindus grew by 16.8% and Muslims by 24.6% in that decade. The other religions also saw growth in their numbers, but they form tiny slices of India’s population pie. Their respective increases are as tiny pieces of the overall population growth numbers.

As you can imagine, the two numbers 24.6% and 16.8% immediately fuelled a deal of comment and speculation. Consider for a start merely how the growth was reported.

The Hindustan Times carried the news under this headline: “Muslim population grows marginally faster." If we’re comparing the decadal growths, the Muslim number is nearly 50% higher than the Hindu number. So, marginally is an odd word to describe that difference. Did the paper look at annual growth, then? Well, the Muslim 24.6% translates to 2.22% a year; the Hindu 16.8% to 1.57% a year. 2.22% is still nearly 50% higher than 1.57%. To me at any rate, marginally just feels wrong. To characterize this gap between the two rates, I would have instead used substantially.

There’s a story behind this, but I’ll come to that.

The Times of India looked at the numbers from another angle. Their headline: “Muslim share of population up 0.8%, Hindus’ down 0.7% between 2001 and 2011." This is because the fraction of the country that identified themselves as Hindus declined from 80.5% in 2001 to 79.8% in 2011, while those who identified as Muslim rose from 13.4% to 14.2%.

This contrast between decline and rise fuels passions in many folks who have, census after census, warned frantically that in our own lifetimes, Hindus will be swamped in their own homeland. Some have even pointed out that this is the first time Hindus have fallen below the “psychologically significant 80% level"—as if one random number out there is more significant than others purely because it has a zero attached to it. The irony that seems to escape such folks entirely is that in nearly seven independent Indian decades, the dreaded swamping has not happened. Not even close.

There’s a story ahead of this, but I’ll come to that as well.

The Hindu had still another take. “Muslim population growth slows", it announced. This really is the first story I mentioned above, and so you might wonder, if I’ve ruled out marginally in favour of substantially, and also mentioned rising shares as opposed to falling ones, what’s all this about slowing?

Let’s get this straight: the Muslim population is growing, as the Indian population is growing. But the rate at which it is growing is slowing, as indeed the Indian population’s growth rate is slowing too. This is clear if you go back one Census. Remember the Muslim population grew by 24.6% between 2001 and 2011? Between 1991 and 2001, it grew by 29.5%. Clearly, this growth has slowed.

One way to appreciate this is to imagine buying a new car. In each of the first two years, you drive 10,000km, for a total of 20,000km. Then it strikes you that you’re spending too much of your kids’ inheritance on petrol, so you resolve to drive less. In the third year, you drive 9,000 km; the fourth year, 8,000. Sure, you’ve not stopped driving and racking up the kilometres on your odometer. But the rate at which you rack them up is slowing.

Muslim growth is substantial, but it is slowing. In fact, it is slowing marginally faster than the Hindu growth is slowing. For between 1991 and 2001, the Hindu share grew by 19.9%. Do the arithmetic yourself—and this time, I believe marginally fits.

The second story I mentioned earlier, the one ahead of us: What the census numbers show is something every developing country experiences—that growth in every segment of the population is slowing and will eventually reach zero. Today, there are 966 million Hindus and 172 million Muslims in India: better than five Hindus to every Muslim. That ratio will never turn radically different, whatever your particular population prism. Mine, incidentally, offers me hope with this number: Between 2001 and 2011, the number of Indians who identified with no religion grew by 294%.

Once a computer scientist, Dilip D’Souza now lives in Mumbai and writes for his dinners. A Matter of Numbers explores the joy of mathematics, with occasional forays into other sciences.

Comments are welcome at dilip@livemint.com. To read Dilip D’Souza’s previous columns, go to www.livemint.com/dilipdsouza-

Close