Richard Posner and Gary Becker have a rare disagreement. Posner writes,

There are three possible responses to the problem created by consumer information costs. The first is to require producers to provide more information; the second is to ban products upon on the basis of a judgment that if consumers knew the score they would not buy the product in question; and the third is to leave the burden of information on the consumer, thereby increasing the incentive of a consumer to inform himself about the products he buys. Often the preferred ranking will be 2, 1, and 3. Banning the product eliminates information costs, though to justify so drastic a measure requires a high degree of confidence that informed consumers would not buy the product if they knew the facts about it. If as I believe trans fats have close and much more healthful substitutes that cost little more than trans fats, the attempt to ban trans fats in New York City restaurants made sense.

Becker writes,

This pressure toward greater regulation of consumer choices is not the result of consumers finding it more difficult to get information about products and the consequences of consuming them. Nor have the cognitive defects referred to by Posner become more prevalent or harmful. Instead, the movement toward increased regulation of consumer choices reflects in large measure greater reluctance among some groups to accept these choices. It is unacceptable to many persons both inside and outside the medical profession that some individuals want to smoke or eat a lot and become overweight, even if they knew and possibly exaggerate the negative health consequences of smoking and overeating. The increase in weight of teenagers, for example, is not explained by cognitive biases, but by sharp declines in the cost of fast foods, and the development of Internet and other sedentary games.Increasing intervention in consumer choices also reflects the erosion of individual responsibility (see my discussion on March 16), so that consumers and their advocates blame others when consumer choices turn out to be harmful and costly.

Suppose that the relevant margin is this: the city of New York can put out an official statement saying that trans fats are really, really bad for you, and that consumers and restaurants should take this into account; vs. the city of New York bans trans fats in restaurants.

In moving from the official statement to the ban, what are the benefits? What are the costs?