Just how seriously should we take those conspiracy theorists and should government be concerned?

Conspiracy theories have probably been around since humankind began to congregate in large numbers, but there is little doubt that the Internet has allowed the genre to flourish and endure as never before.
So much so that academic papers are now written on the subject.

Many millions of people hold conspiracy theories; they believe that powerful people have worked together in order to withhold the truth about some important practice or some terrible event. A recent example is the belief, widespread in some parts of the world, that the attacks of 9/11 were carried out not by Al Qaeda, but by Israel or the United States. Those who subscribe to conspiracy theories may create serious risks, including risks of violence, and the existence of such theories raises significant challenges for policy and law. The first challenge is to understand the mechanisms by which conspiracy theories prosper; the second challenge is to understand how such theories might be undermined. Such theories typically spread as a result of identifiable cognitive blunders, operating in conjunction with informational and reputational influences. A distinctive feature of conspiracy theories is their self-sealing quality. Conspiracy theorists are not likely to be persuaded by an attempt to dispel their theories; they may even characterize that very attempt as further proof of the conspiracy. Because those who hold conspiracy theories typically suffer from a crippled epistemology, in accordance with which it is rational to hold such theories, the best response consists in cognitive infiltration of extremist groups. Various policy dilemmas, such as the question whether it is better for government to rebut conspiracy theories or to ignore them, are explored in this light. [Sunstein, Cass R. and Vermeule, Adrian, Conspiracy Theories (January 15, 2008), Harvard Public Law Working Papers,SSRN abstract] Download full paper here.

What the authors are politely implying is that conspiracy theorists are often credulous and ignorant. What they appear to be advocating is intervention on extremist websites and fora, by salting these venues with government-approved alternative explanations either openly or anonymously.

But should government be encouraged to act in a surreptitious manner?
Will anonymous debate by government agencies only confuse the legitimacy/strength of any response to a social or political issue, no matter how far out that response may become?
Aren't the crooked debating techniques which government already frequently employs (along with the PR firms it sometimes hires to assist) enough of a burden in any public debate?
Are conspiracy theories generally so destructive that they warrant government action by way of blogosphere black-ops?

Some false conspiracies manifest as rather vaguely held beliefs like this one found at Agmates Community Site:
Communists now control the executive branch of the US government. They completely control the Secretariat of the UN. They tried to deal with Lord Monckton at Copenhagen.
They control many bureaucracies in Australia including CSIRO. This is not a good situation. It is time for action! It is time for the silent majority to stand up.

While others are more elaborate constructions such as the enduring threat of Illuminati world domination by 'lizard' people. This classic example was found at Educate-Yourself:
There is a worldwide conspiracy being orchestrated by an extremely powerful and influential group of genetically-related individuals (at least at the highest echelons) which include many of the world's wealthiest people, top political leaders, and corporate elite, as well as members of the so-called Black Nobility of Europe (dominated by the British Crown) whose goal is to create a One World (fascist) Government, stripped of nationalistic and regional boundaries, that is obedient to their agenda. Their intention is to effect complete and total control over every human being on the planet and to dramatically reduce the world's population by 5.5 Billion people. While the name New World Order is a term frequently used today when referring to this group, it's more useful to identify the principal organizations, institutions, and individuals who make up this vast interlocking spiderweb of elite conspirators.....

Some potential conspiracies register on the news cycle and then fade away:
Is information warfare to blame for the damage to underwater internet cables that has interrupted internet service to millions of people in India and Egypt, or is it just a series of accidents?

Yet others are elaborate constructions, such as alternative explanations for the collapse of the World Trade Towers in New York found within the broad church which is the 9/11 Truth Movement:
In this paper, I call for a serious investigation of the hypothesis that WTC 7 and the Twin Towers were brought down, not just by impact damage and fires, but through the use of pre-positioned cutter-charges. I consider the official FEMA, NIST, and 9-11 Commission reports that fires plus impact damage alone caused complete collapses of all three buildings. And I present evidence for the controlled-demolition hypothesis, which is suggested by the available data, and can be tested scientifically, and yet has not been analyzed in any of the reports funded by the US government. [Jones, SE (2006) "Why indeed did the WTC Buildings Completely Collapse?",Journal of 9/11 Studies]

A few can be said to have had widespread mainstream media dissemination, such as the al Fayed assertion that his son and Princess Diana were murdered. A belief which saw cause of death open to debate for a number of years until a much-delayed formal inquest.

More than one conspiracy theory appears to have had a strong political impact.
The 9/11 theories and the "there is no man-made global warming' view would have to fall into this category. The former because so many individuals in Muslim countries appear to believe that Islamic extremists were not involved in the attack and the latter because it has given conservative politicians and polluting industries an excuse to either ignore or sideline the issue of catastrophic climate change.

This is an early example of The Myth of Global Warming:
The SwindleThe Great Global Warming Swindle
Sea Levels Not Rising Except In The Lies of the IPCC
Solar Cycles, Not CO2 Determine Climate Global Climate Explained (If you Want To Worry)
Suspend Disaster The Myth Of Global Warming
A Load Of Hot Air Climate Change Hysteria is Costing Us
The Ice Age Cometh The Real Danger Of An Ice Age
Global Warming Messy Models, Decent Data, and Pointless Policy
Hot Politics Doctoring Of Reports By UN Experts
Cool Climate The Absurdity Of Trying To Control Climate
A Pagan Fantasy The Effect Of Accepting Popular Paranoia As Truth

With what is possibly the largest modern anti-science set of beliefs, the Global Warming Conspiracy, developing a loose but increasingly sophisticated organizational structure, its claims becoming even more brazen and its media coverage almost guaranteed, I suspect that the real question politicians are privately asking each other is "Will this false {insert name} conspiracy theory change voter intention and will this be to my advantage?"

I expect that during the Australian federal and state election campaigns in 2010 voters will have to keep a wary eye on the origins of all forms of information, because I cannot see any political party resisting the urge to secretly insert its own brand of misinformation into the online political debate through a multitude of "Stan of Wagga Wagga", "Cheryl at Toongabbie", Marge from Moonee Ponds" and "Bruce via Brisbane" false persona or the mainstream media forego the urge to foster its own political pets with a plethora of unsupported "unnamed sources".