KEY POINTS:
The Law of Unintended Consequences holds that purposeful actions, especially by governments, have unanticipated results.
It differs from Murphy's Law - if anything can go wrong, it will - in that it doesn't take failure for granted. Notwithstanding the unintended consequences, the desired outcome may be partially or
largely achieved. Secondly, the unintended consequences aren't necessarily negative.
In 1936 American sociologist Robert Merton distilled centuries of folklore, cautionary tales, common sense, superstition and social observation into a paper entitled "The Unanticipated Consequences of Purposive Social Action".
To illustrate his thesis he observed that by generating wealth the Protestant work ethic contributed to its own decline.
He was merely embellishing the old saying "Shirtsleeves to shirtsleeves in three generations". Through hard work and thrift the first generation accumulates wealth that fuels the next generation's upward social mobility; the third generation, born into a life of ease and privilege, then squanders the family fortune.
This week the Brisbane Broncos rugby league club CEO invoked the law to explain the oafishness and worse that bedevils many NRL teams.
The salary cap has created a more even competition but, according to Bruno Cullen, it has also forced clubs to shed the mature, experienced players who previously set an example of professionalism and kept the younger players in line.
History abounds with examples, often farcical or tragic. In his famous work The Origins of the Second World War, historian A. J. P. Taylor argued that the seeds of Nazism were sown in the vengeful reparations imposed on Germany after World War I. (Before the Treaty of Versailles a British Cabinet minister promised to "squeeze the German lemon until the pips squeak".)
America's covert role in the USSR's costly entanglement in Afghanistan was seen as one of the CIA's finest hours - and payback for the Soviet Union's part in sending the US packing from Vietnam.
The Americans were too busy patting themselves on the back to notice that the mujahedeen whom they'd trained and equipped, including the young Osama bin Laden, weren't merely anti-communist, they were militantly anti-anyone who wasn't Islamist.
The CIA term for unintended consequences is "blowback". In this case blowback came in the form of the Taleban and 9/11.
The War on Drugs could be considered the epitome in that it has by and large achieved the exact opposite of what was intended. It's a classic example of what Merton called the "imperious immediacy of interest" - when an outcome is so intensely desired and pursued that the damage done in the process is wilfully ignored.
On the other hand it could be argued that seeing the Prohibition Era provided a blueprint for how not to tackle this type of problem, the War on Drugs should simply be dismissed as malign stupidity rather than dignified with a quasi-academic label.
Critics of the progressive movement and political correctness detect examples everywhere, although the unintended consequences often say more about Homo sapiens than the actual measures.
The drastic toughening up of the drink-driving regime is said to have reduced social intercourse in rural areas and, in the US, led to an increase in hit and runs.
US research detected a clear statistical co-relation between the introduction of legalised abortion and the marked drop in crime rates that occurred in the 1990s.
The Law of Unintended Consequences is often invoked by philosophical conservatives who believe mankind's innate folly condemns us to living in an imperfect world so we should just go with the flow, and laissez-faire capitalists who believe markets are much more efficient than governments.
Strangely enough, this belief in the market's Darwinian rigour doesn't preclude taxpayer bailouts.
The scale of the measures taken by governments to shore up the financial system and the haste with which they were implemented ensures that there will be unintended consequences.
Apart from anything else there will also be a degree of trepidation among those who remember the not-so-golden age of public ownership.
The historians will tally up the unintended consequences and make their judgments.
There are times when inaction is not an option and this is one of them.