Some object that the mayor’s proposal to restrict serving sizes will restrict liberty. But the liberty restricted is not the liberty of the soda-drinker. If they wish, soda drinkers can buy a 2-liter bottle of soda at the grocery for about $1.70 and pour as much of it down their throats as they wish. The liberty that is being restricted is the liberty of the soda seller to manipulate known human weaknesses to the seller’s advantage and the buyer’s detriment.

Human beings are not reasoning machines. We are animals who have inherited certain propensities not always well-adapted to modern urban life. We evolved in conditions of food scarcity. Our bodies have adapted to store food energy against famine; our subrational minds crave sweetness. The sugary beverage industry has invested massively to understand better how to use our very human natures against us…

But if a restraint on soda serving size will not do everything, it may still do something. Or possibly not. The idea may fail. The idea is an experiment, and most experiments fail. We learn from failure how to design a better effort next time. And when we do at least succeed in this difficult struggle for public health, we will all owe New York’s visionary mayor our thanks for leading the way.