The law of unintended consequences is at work always and everywhere
The law of
unintended consequences, often cited but rarely defined, is that actions of
people—and especially of government—always have effects that are unanticipated
or unintended. Economists and other social scientists have heeded its power for
centuries; for just as long, politicians and popular opinion have largely
ignored it.
The concept of
unintended consequences is one of the building blocks of economics. Adam Smith’s “invisible
hand,” the most famous metaphor in social science, is an example of a positive
unintended consequence. Smith maintained that each individual, seeking only his
own gain, “is led by an invisible hand to promote an end which was no part of
his intention,” that end being the public interest. “It is not from the
benevolence of the butcher, or the baker, that we expect our dinner,” Smith
wrote, “but from regard to their own self interest.”
Most often,
however, the law of unintended consequences illuminates the perverse
unanticipated effects of legislation and regulation. In 1692 the
English philosopher John Locke, a forerunner of
modern economists, urged the defeat of a parliamentary bill designed to cut the
maximum permissible rate of interest from 6 percent to 4 percent. Locke argued
that instead of benefiting borrowers, as intended, it would hurt them. People
would find ways to circumvent the law, with the costs of circumvention borne by
borrowers. To the extent the law was obeyed, Locke concluded, the chief results
would be less available credit and a redistribution of income
away from “widows, orphans and all those who have their estates in money.”
In the first half
of the nineteenth century, the famous French economic journalist Frédéric Bastiat often
distinguished in his writing between the “seen” and the “unseen.” The seen were
the obvious visible consequences of an action or policy. The unseen were the
less obvious, and often unintended, consequences. In his famous essay “What Is Seen and What Is
Not Seen,” Bastiat wrote:
There is only one difference between a bad economist and a good one: the bad economist confines himself to the visible effect; the good economist takes into account both the effect that can be seen and those effects that must be foreseen.(1)
Bastiat applied
his analysis to a wide range of issues, including trade barriers, taxes, and
government spending.
The first and most
complete analysis of the concept of unintended consequences was done in 1936 by
the American sociologist Robert K. Merton. In an influential article titled
“The Unanticipated Consequences of Purposive Social Action,” Merton identified
five sources of unanticipated consequences. The first two—and the most
pervasive—were “ignorance” and “error.”
















