"The idea of the state stepping in and treating adults essentially as children and trying to protect them for their own good, as opposed to the good of others, that's been with us for as long as we've been around, as long as we've had governments," says Glen Whitman, an economist at California State University-Northridge who is a critic of paternalistic public policy.
The most famous example was Prohibition, which barred the manufacture and sale of alcohol from 1919 to 1933. But Whitman and others see a new wave of intervention afoot, based on behavioral economics rather than religious moralism, and symbolized by moves like Bloomberg's. Allow it to continue, they say, and who knows where it could lead?
If government officials can limit the size of sodas, why couldn't they next decide to restrict portion sizes of food served in restaurants or the size of pre-made meals sold at supermarkets? Why wouldn't a government determined to curb obesity restrict sales of doughnuts or pastries or - perish the thought, New Yorkers - ban bagels with a schmeer of cream cheese?
If government is within its right to restrict behavior to protect health, then why wouldn't a mayor or other official ban risky sexual conduct or dangerous sports like skydiving? What's to stop a mayor from requiring people to wear a certain type of sunscreen or limit the amount of time they can spend on the beach, to protect them from skin cancer?
The more ho-hum reality is that many of the policies restricting individual choice in the name of public health seem almost benign, like curbs on fireworks sales or enforcement of motorcycle helmet laws. But such moves represent a "constant creep until all of a sudden its extremely obvious," said Mattie Duppler of Americans for Tax Reform, a conservative anti-tax lobbying group that regularly spotlights examples of what it considers overreaching "Nanny State" public policy.
She points to moves by governments, like the city of Richmond, Calif., to impose taxes on sugary sodas and moves by states like Utah, which widened a ban on indoor smoking in public places to include electronic cigarettes that don't emit smoke.
"What we're seeing is government trying to put its fingers around the throat of anything that claims public health impetus," Duppler says.
Others, though, have their doubts. Richard Thaler, co-author of "Nudge: Improving Decisions About Health, Wealth and Happiness," which argues for policies that encourage rather than mandate changes in consumer behavior, calls Bloomberg's soda proposal "inartful and probably ineffective and too heavy-handed for my taste."
But for him, most of the questions it raises are about practicality, rather than red flags.
Would a Bloomberg curb on big drinks ban free refills, asks Thaler, an economist at the University of Chicago? Would it ban special offers to buy one drink and get the second at half-price?
Thaler, who says he is against government mandates or bans, argues that governments will get the most mileage from policies that nudge behavior, like placing fruit more prominently in school cafeterias. But he dismisses warnings that government efforts to improve public health risks sending the country down a slippery slope of more control and less individual choice.
"Any time people do something that people don't like, they predict it will lead to something awful," Thaler said. "I have not seen a big trend of governments becoming more intrusive."
Even Duppler has her doubts about what Bloomberg's soda proposal represents. It may be so politically iffy that it fizzles before it even gets off the ground. Then again, you never know what to expect from the city that never sleeps - and no longer smokes in bars, in airports or in the park.
"We'll see," she says of the soda proposal. "There's some crazy ideas - and sometimes they just take hold."