For example, why not have a congressionally mandated 5 miles per hour highway speed limit? According to the U.S. Department of Transportation, there were 43,220 highway fatalities in 2003, with an estimated cost of $230 billion. A 5 mph speed limit would have spared our nation this loss of life and billions of dollars. You say, "Williams, that's preposterous!" You're right. Most people would agree that a 5 mph speed limit is stupid, impractical and insane. That's one way of putting it, but what they really mean is: The benefit of saving 43,220 highway deaths and the $230 billion that would result from mandating a 5 mph speed limit isn't worth all the inconvenience, delays and misery.
Admittedly, the 5 mph speed limit is an extreme example, a reductio ad absurdum. Nonetheless, it illustrates the principle that our actions shouldn't be guided by benefits only; we should also ask about costs. Again, when politicians come to us pretending they're Santa Clauses or tooth fairies delivering benefits only, we should ask what's the cost, who's going to pay and why.