Take a policy as simple as reducing the dangers of smoking by cutting tar and nicotine in cigarettes. It sounds great in theory, particularly when used in conjunction with a clever marketing campaign. It looks like a ballistic strategy perfectly designed to hit an important public health target. But when this idea was implemented in practice, it failed. Smokers compensated for the lack of nicotine by smoking more cigarettes and taking longer and deeper drags. The net result was an increase in carcinogens and carbon monoxide.
