Unintended consequences are a common phenomenon, due to the complexity of the world and human over-confidence. The
Law of unintended consequences holds that almost all human actions have at least one unintended consequence.
Much of this is due to the complexity of the world, although a certain amount can also be attributed to human stupidity[?] and self-deception[?].
The most common kind of unintended consequences arise from perverse incentives, a term for an incentive[?] that has the opposite effect to that intended. See the article on perverse incentives for many examples of this.
Other examples of unintended consequences:
- "Prohibition", intended to suppress the alcohol trade, drove many small-time alcohol suppliers out of business, consolidating the hold of large-scale organized crime over the illegal alcohol industry.
- Sixty years later, the "War on Drugs", intended to suppress the illegal drug trade, has driven many small-time drugs dealers out of business, consolidating the hold of large-scale organized crime over the illegal drugs industry.
- The introduction of rabbits into Australia for sport led to an explosive growth in population, and led to rabbits becoming a major pest in Australia.
- In CIA jargon, blowback describes the phenomenon of supporting a foreign regime or terrorist entity, on the principle that your enemy's enemy is your friend, only to have it attack you, often with the weapons and resources you gave it. Examples include:
- John Sloan III, Tomislav V. Kovandzic and Lynee M. Vieraitis. Unintended Consequences of Politically Popular Sentencing Policy: The Homicide-Promoting Effects of 'Three Strikes' in U.S. Cities (1980-1999). Criminology & Public Policy, Vol 1, Issue 3, July 2002.