part because firms that emit large amounts of greenhouse gases pay only a
small share of the cost of those emissions. Indeed, even the countries in
which they reside do not bear the full cost of the pollution. A steel plant in
Pennsylvania emits CO
2
that may one day cause a flood in Bangladesh.
(Meanwhile, acid rain caused by U.S. emissions is already killing Canadian
forests.) The same thing is true in all kinds of factories around the world.
Any solution to global warming will have to raise the cost of emitting
greenhouse gases in a way that is binding upon all of the earth’s polluters—
not the easiest of tasks.
It is worth noting that there can be positive externalities as well; an
individual’s behavior can have a positive impact on society for which he or she
is not fully compensated. I once had an office window that looked out across the
Chicago River at the Wrigley Building and the Tribune Tower, two of the most
beautiful buildings in a city renowned for its architecture. On a clear day, the
view of the skyline, and of these two buildings in particular, was positively
inspiring. But I spent five years in that office without paying for the utility that I
derived from this wonderful architecture. I didn’t mail a check to the Tribune
Company every time I glanced out the window. Or, in the realm of economic
development, a business may invest in a downtrodden neighborhood in a way
that attracts other kinds of investment. Yet this business is not compensated for
anchoring what may become an economic revitalization, which is why local
governments often offer subsidies for such investment.
Some activities have both positive and negative externalities. Cigarettes kill
people who smoke them; that is old news. Responsible adults are free to smoke
or not smoke as they choose. But cigarette smoke can also harm those who
happen to be lingering nearby, which is why most office buildings consider
smoking to be slightly less acceptable than running through the halls naked.
Meanwhile, all fifty states filed suit against the tobacco industry (and
subsequently accepted large settlements) on the grounds that smokers generate
extra health care costs that must be borne by state governments. In other words,
my taxes go to remove part of some smoker’s lung. (Private insurance
companies do not have this problem; they simply recoup the extra cost of
insuring smokers by charging them higher premiums.)
At the same time, smokers do provide a benefit to the rest of us. They die
young. According to the American Lung Association, the average smoker dies
seven years earlier than the average nonsmoker, which means that smokers pay
into Social Security and private pension funds for all of their working lives but
then don’t stick around very long to collect the benefits. Nonsmokers, on
average, get more back relative to what they paid in. The good folks at Philip
Morris have even quantified this benefit for us. In 2001, they released a report on
the Czech Republic (just as parliament was considering raising cigarette taxes)
showing that premature deaths from smoking save the Czech government
roughly $28 million a year in pension and old-age housing benefits. The net
benefit of smoking to the government, including taxes and subtracting public
health costs, was reckoned to be $148 million.
3
How does a market economy deal with externalities? Sometimes the
government regulates the affected activity. The federal government issues
thousands of pages of regulations every year on everything from groundwater
contamination to poultry inspection. The states have their own regulatory
structures; California, for example, has a strict set of emissions standards for
automobiles. Local governments have zoning laws that forbid private property
owners from impinging on their neighbors by constructing buildings that may be
unsafe, inappropriate for the neighborhood, or simply ugly. The island of
Nantucket allows only a few select colors of exterior paint lest irresponsible
property owners use neon colors that would destroy the quaint character of the
island. I live in a historic neighborhood in which every external change to our
homes—from the color of new windows to the size of a flower box—must be
approved by an architecture committee.
There is another approach to dealing with externalities that tends to be favored
in some cases by economists: taxing the offending behavior rather than banning
it. I’ve conceded that my Ford Explorer was a menace to society. As Cornell
economist Robert Frank noted in an op-ed for the New York Times, we are
locked in an SUV arms race. “Any family can only choose the size of its own
vehicle. It cannot dictate what others buy. Any family that unilaterally bought a
smaller vehicle might thus put itself at risk by unilaterally disarming,” he wrote.
4
Should the Hummer be banned? Should Detroit be ordered to manufacture safer,
more fuel-efficient cars?
Economists, including Mr. Frank, would argue not. The primary problem with
SUVs—and all vehicles, for that matter—is that they are too cheap to drive. The
private cost of driving a Hummer to the grocery store is obviously far lower than
the social cost. So raise the private cost. As Mr. Frank writes, “The only
practical remedy, given the undeniable fact that driving bulky, polluting vehicles
causes damage to others, is to give ourselves an incentive to take this damage
into account when deciding what vehicles to buy.” If the real cost to society of
having an Explorer on the road is 75 cents a mile instead of the 50 cents a mile
that it costs the vehicle’s owner to operate the vehicle, then tack on a tax that
equates the two. This might be accomplished with a gas tax, or an emissions tax,
or a weight tax, or some combination thereof. The result will make driving a
Hummer to the grocery store a lot less attractive.
But now we have entered strange terrain. Is it appropriate to allow some
drivers to pay for the privilege of driving a vehicle so bulky that it might run
over a Mini Cooper without even spilling the sixty-four-ounce drink in the
monster cup holder? Yes, for the same reason that most of us eat ice cream even
though it causes heart disease. We weigh the health costs of Starbucks Almond
Fudge against that divine, creamy taste and decide to have a pint every once in a
while. We don’t quit ice cream entirely, nor do we have it with every meal.
Economics tells us that the environment requires the same kinds of tradeoffs as
everything else in life. We should raise the cost of driving an SUV (or any
vehicle) to reflect its true social cost and then let individual drivers decide if it
still makes sense to commute forty-five miles to work in a Chevy Tahoe.
Taxing a behavior that generates a negative externality creates a lot of good
incentives. First, it limits the behavior. If the cost of driving a Ford Explorer
goes to 75 cents a mile, then there will be fewer Explorers on the road. As
important, those people who are still driving them—and paying the full social
freight—will be those who value driving an SUV the most, perhaps because they
actually haul things or drive off-road. Second, a gas-guzzler tax raises revenue,
which a ban on certain kinds of vehicles does not. That revenue might be used to
pay for some of the costs of global warming (such as research into alternative
energy sources, or at least building a dike around some of those Pacific island
nations). Or it might be used to reduce some other tax, such as the income or
payroll tax, that discourages behavior we would rather encourage.
Third, a tax that falls most heavily on hulking, fuel-hungry vehicles will
encourage Detroit to build more fuel-efficient cars, albeit with a carrot rather
than a stick. If Washington arbitrarily bans vehicles that get less than eighteen
miles per gallon without raising the cost of driving those vehicles, then Detroit
will produce a lot of vehicles that get—no big surprise here—about eighteen
miles a gallon. Not twenty, not twenty-eight, not sixty using new solar
technology. On the other hand, if consumers are going to be stuck with a tax
based on fuel consumption and/or the mass of the vehicle, then they will have
very different preferences when they step into the showroom. The automakers
will respond quickly, and other products like the Hummer will be sent where
they belong, to some kind of museum for mutant industrial products.
Is taxing externalities a perfect solution? No, far from it. The auto example
alone has a number of problems, the most obvious of which is getting the size of
the tax right. Scientists are not yet in complete agreement on how quickly global
warming is happening, let alone what the costs might be, or, many steps beyond
that, what the real cost of driving a Hummer for a mile might be. Is the right tax
$0.75, $2.21, $3.07? You will never get a group of scientists to agree on that, let
alone the Congress of the United States. There is an equity problem, too. I have
stipulated correctly that if we raise the cost of driving gas guzzlers, then those
who value them most will continue to drive them. But our measure of how much
we value something is how much we are willing to pay for it—and the rich can
always pay more for something than everyone else. If the cost of driving an
Explorer goes to $9 a gallon, then the people driving them might be hauling
wine and cheese to beach parties on Nantucket while a contractor in Chicago
who needs a pickup truck to haul lumber and bricks can no longer afford it. Who
really “values” their vehicle more? (Clever politicians might get around the
equity issue by using a tax on gas guzzlers to offset a tax that falls most heavily
on the middle class, such as the payroll tax, in which case our Chicago
contractor would pay more for his truck but less to the IRS.) And last, the
process of finding and taxing externalities can get out of control. Every activity
generates an externality at some level. Any thoughtful policy analyst knows that
some individuals who wear spandex in public should be taxed, if not jailed. I live
in Chicago, where hordes of pasty people, having spent the winter indoors on the
couch, flock outside in skimpy clothing on the first day in which the temperature
rises above fifty degrees. This can be a scary experience for those forced to
witness it and is certainly something that young children should never have to
experience. Still, a tax on spandex is probably not practical.
I’ve wandered from my original, more important point. Anyone who tells you
that markets left to their own devices will always lead to socially beneficial
outcomes is talking utter nonsense. Markets alone fail to make us better off when
there is a large gap between the private cost of some activity and the social cost.
Reasonable people can and should debate what the appropriate remedy might be.
Often it will involve government.
Of course, sometimes it may not. The parties involved in an externality have
an incentive to come to a private agreement on their own. This was the insight of
Ronald Coase, a University of Chicago economist who won the Nobel Prize in
1991. If the circumstances are right, one party to an externality can pay the other
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