"India is very robust, frustratingly robust democracy which means that there are multiple centres of power, multiple centres of decision making, multiple centres of veto exercise in authorities. This is not a country where you can pull a switch and say let's do reform," he said.
At the same time, the former IMF economist termed the revised GDP growth figures as a "puzzle" and said that the numbers have been "bumped up" and it is a mystery how to interpret them.
Subramanian, who earlier also termed the the revised GDP figures as "puzzling", was delivering a lecture at Panjab University on 'Economic Survey 2014-15'.
"In robust democracy, you do not get big bang reforms. It is not easy to do this thing," he said.
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He noted that the big bang reforms took place only when a country was facing a crisis.
"If you look around the world how the countries have done in last 50-60 or 100 years, you will find out that what we call big bang reforms that was the expectations, a lot of reform took place in the (union) budget.
Describing India as a "recovering economy", the Chief Economic Adviser said that the country was growing "well below its potential".
"We should see India as more of a recovering economy not as an economy that is surging at a rate of 8-8.5 per cent. Even the number is 8 and 8.5 per cent but it growing well below its potential," he said.
However, he described growth numbers are a "bit of puzzle" because of new estimates.
"New growth numbers are a bit of puzzle. Our growth rates have been bumped up after by new estimates that have come up by statisticians...It is a bit of mystery how to interpret it.
If you look at all indicators of Indian economy, like credit growth, tax collection, that do not seem to be consistent with the economy supposedly growing at 7.5 pc or so," he said.