In a New York Times op-ed this morning, Daniel E. Lieberman, an evolutionary biologist at Harvard, makes a strong case for our strong attraction to sugar, but a weak case for paternalistic action on the part of the government to limit our consumption of it.

The problem is captured by the question he poses after he lays out the scientific reasoning: "What should we do?" Professor Lieberman somehow makes the leap from "people are eating too much sugar" to "the government should do something to stop this" without appreciating the size of the chasm he's jumping. (Just ask David Hume.) He fails to explain why this is a problem that justifies government intrusion into the choices of individuals—he simply takes it for granted that because we have evolved to crave more sugar than he thinks is optimal, the government is entitled to adjust our sugar consumption to bring it in line with what he thinks is optimal.

This is yet another example of the most offensive aspect of paternalism: value substitution. We are lucky to have access to Professor Lieberman's scientific insights regarding why we crave sugar so much. But then he asserts his opinion that we eat too much sugar, based on his opinion regarding our optimal diets (based on our ancestors' nutritional nirvana long before Coca-Cola and Nabisco). This much is fine—everyone is entitled to his (or her) opinion, and he is fortunate that The New York Times gives him a platform to express it. But like all who endorse paternalism based on what they think we can do better, Professor Lieberman crosses a line when he shifts from expressing his opinion regarding our behavior to endorsing government action to adjust our behavior based on that opinion.

But isn't it commonsense that we should eat less sugar (and salt, and trans fats) and more healthy foods? Of course. But is that all our only concern? Is it our only interest? Should it be? Not only does value substitution mispresent our true interests, but it only greatly oversimplifies them. I know I shouldn't eat too much sugar. But I also think a sugary treat or drink is a fine complement to a meal, or the cornerstone of a celebration, or a nice way to acknowledge a job well. People's interests are complex, and while they do include health, they also include a myriad of other things, things that are ignored when a scientific expert or government regulator proclaims, "Too much! Too much!"

After making a reasonable case for limiting unhealthy foods in schools--a proposal I have very little problem with—Professor Lieberman proclaims that "adults need help too." This is the paternalistic mindset in a nutshell: you need help because we know better than you how you should run your life. Again, he makes a tremendous leap, from "you are being tempted by cheap sugar from the food industry" to "you need the government to step in and counter this influence." First, there is no way to know how much sugar consumption is due to "irresistible temptation" and how much is due to open-eyed choice. Paternalistic regulation—whether in the form of prohibition, taxes, or nudges—is a blunt tool that misses the nuances of human decision-making.

Second, this treats people as slaves to their passions—there's Hume again—which must be manipulated by the state to counter manipulation by industry. Professor Lieberman devotes just two sentences to spreading information, but decides that it hasn't done enough—"enough," of course, based on his opinion regarding what should have happened. But here's another possibility: people know how bad sugar is from them, and armed with that information plus all of their multifaceted interests, they nonetheless choose to eat more sugar than Professor Lieberman would like them to.

Professor Lieberman concludes with this: "We have evolved to need coercion." I hope he's not making that claim on the basis on his scientific expertise, because science cannot tell us what we need. Science can help explain why we do what we do—as Professor Lieberman well details in the early part of his article—but it has nothing to contribute to what we need. Such a proclamation requires knowledge of our goals, interests, or "purpose"—the last one a teleological notion which scientists normally disavow—and none of which science or government knows better than people themselves.


This post originally appeared at the Economics and Ethics blog.

You can follow me on Twitter and also at the following blogs: Economics and Ethics, The Comics Professor, and my homepage/blog.

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