Excerpts

"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 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.

Merton labeled the third source the "imperious immediacy of interest." By that he was referring to instances in which an individual wants the intended consequence of an action so much that he purposefully chooses to ignore any unintended effects. (That type of willful ignorance is very different from true ignorance.) A nation, for example, might ban abortion on moral grounds even though children born as a result of the policy may be unwanted and likely to be more dependent on the state. The unwanted children are an unintended consequence of banning abortions, but not an unforeseen one.

"Basic values" was Merton's fourth example. The Protestant ethic of hard work and asceticism, he wrote, "paradoxically leads to its own decline through the accumulation of wealth and possessions." His final case was the "self-defeating prediction." Here he was referring to the instances when the public prediction of a social development proves false precisely because the prediction changes the course of history. For example, the warnings earlier in this century that population growth would lead to mass starvation helped spur scientific breakthroughs in agricultural productivity that have since made it unlikely that the gloomy prophecy will come true..."

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