Many things Modeled Behavior come up in Matt Ridley’s suggestion that we use vouchers to combat obesity.

After all, as Friedrich Hayek pointed out, the true genius of markets is that they discover things. Perhaps the answer to obesity is to spend money not on the producers (of gyms, diets, surgery, vegetables) but on the consumers.

Well somewhat.

The genius of the market is the way it aggregates masses of information that no single individual could possibly possess and subjects scores of untestable hypothesis to the forces of economic evolution. This allows us to do without knowing what we do and to design without a designer. Great and beautiful things.

However, raw scientific and administrative knowledge are powerful things as well. Indeed this is revealed by the emergence of socialism as a doctrine. It was in large part the ability of technocracy to win wars, purify water and cure diseases that inspired folks to believe that technocracy could do anything.

Drawing a direct analogy with the effect of vouchers in the education system, Messrs. Seeman and Luciani suggest “healthy-living vouchers” that could be redeemed from different (certified) places—gyms, diet classes, vegetable sellers and more. Education vouchers, they point out, are generally disliked by rich whites as being bad for poor blacks—and generally liked by poor blacks. A bottom-up solution empowers people better than top-down government fiat.

This is certainly true, though I am not sure it really gets you anywhere. Lack of empowerment doesn’t seem to be the core problem here. The number of private weight loss attempts that fail every year far exceed those that succeed. People can and do try wacky individualized weight loss programs. Entrepreneurs can and do promote all manner of weight loss products.  The overwhelming majority just fail.

After all, the root causes of obesity are multifarious and new ones are being added all the time—such as diet sodas, gut bacteria, genes, sleep apnea, leptin levels, medication, depression, poverty and peer pressure. So the solutions need to be multipronged, too. What works for you may not work for me.

The underlying notion here – that the obesity epidemic is a multipronged problem with lots of individual causes – is likely wrong. There are lots of levers with which one can attack obesity. There are lots of failsafe systems that exist in the regulation of appetite and activity and they can be overridden in different ways. However, the odds that an epidemic with the steady widespread march of obesity is multi-factor are slim. There is probably a single cause and it probably operates directly on the endocrine system. Of course at this point we don’t know what it is, but I suspect that it is a particular molecule or class of molecules.

People in the future will think it as toxic and find it amazing that we were so careless with it. The same way we think it maddening that children used to play with mercury.

In due course, the obesity problem will be solved, I suspect. The ultra-rich have already solved it. Most of them are very thin these days, quite unlike in ancient times. That’s because they can afford the solutions that work for them, from low-carb diets to personal trainers.

In due course I expect it to be solved as well. However, the notion that the ultra-rich have solved it is wrong. First, off there are obviously selection effects that decrease obesity levels among the rich. You are more likely to become rich, by business success and especially by marriage, if you are thin.

Second, we know that susceptibility to obesity is highly heritable. This means that the children of a rich spouse and a thin spouse are more likely to be both rich and thin. A similar effect happens with height. The rich are likely to be tall. Yet, this isn’t because they’ve found a solution to shortness.

Third, as Ridley suggests the rich are spending lots of time and money on combatting what obesity they have. This is not solving the problem. This is managing the symptoms of the problem. Whatever underlying condition is forcing you to expend all of this effort still exists. Its that underlying condition that we want to cure.

For example, managing Tuberculosis by moving to a dryer climate is better than dying in the sewers of Paris, but its not the same as curing TB. Tuberculosis in some ways provides an analog to obesity. It is a disease that has been with us since antiquity yet saw an enormous, at the time inexplicable, spike in the 18th century.

Theories on the cause of tuberculosis ranged from vampirism to masturbation to impure air. It was argued that a variety of maladies could lead one to succumb to Consumption, as it was then known. Consumption was also endemic among the urban poor, a fact sometimes attributed to their low moral character.

Yet, in the end it was a single disease with a single cause and streptomycin was the cure.