Two weeks after the third anniversary of the Madrid train bombings that killed 161 people, conspiracy theories are circulating in Spain with surprising popularity. A poll shows that roughly 36% percent of Spaniards do not believe that Islamist militants were responsible for the March 11, 2004, attacks. 

Many suspect that militant Basque separatists from the terrorist group ETA actually carried out the bombing.  They also think the Spanish government has covered up the truth.  The conservative Popular Party promotes these theories, featuring them prominently in the metropolitan daily El Mundo.  

The conservatives have ulterior motives.  The Popular Party was forced out by voters angry over its attempts to pin the blame for the train bombings on Basque separatists even when overwhelming evidence suggested the attack was carried out by affiliates of Morocco's Islamist Combat Group.

Yet even in the face of such evidence, a substantial slice of the population ardently believes that the socialist Zapatero government, elected by voters angry over Spain's participation in the Iraq war, covered up or destroyed evidence that would have exonerated the Popular Party by establishing the ETA's guilt.

Spain's experience is by no means unique. In Britain, wild theories circulate around the Internet that the July 7, 2005, subway bombings by Al Qaeda were in fact "false-flag" operations.  Conspiracy theorists say the attacks were planned by the government to drum up support for the pro-war agenda of the Bush/Blair governments and foment anti-Muslim feelings. Other variants include speculation that the CIA or Mossad was involved, or that the British government let the operation happen.

And in the United States, 36% of Americans believe that the government either planned the 9/11 attacks themselves or allowed them to happen.  Why?  To give the Bush administration a justification for invading Afghanistan and Iraq, taking their oil, and repressing civil liberties. Members of groups like the 9/11 Truth Movement have amassed a popular following that includes academics and celebrities, not just the usual conspiracy nuts.

In all three cases, massive cover-ups allegedly further sinister geopolitical plans. The conspiracy narrative is depressingly formulaic: a massive crime has been committed to fool the populace into advancing a hidden agenda.  Evidence is destroyed, faked, or tampered with; witnesses and informers are either disregarded or silenced; the perpetrators are government agents or patsies manipulated into killing themselves for an evil agenda; and any proof to the contrary has been fabricated.

An effect of suicide terrorism against Western nations is that citizens develop distrust and suspicion of their own government.  Contradictory news reports fuel this chaos. On 9/11, frantic reporters falsely reported that bombs had been placed under the George Washington Bridge. Even after things return to normalcy, these reports are often neither retracted nor discussed.

Other factors also fuel conspiracy theories. The public does not read lengthy investigative papers but instead watches the news. And governments sometimes impede investigations in order to discourage the release of information that pins responsibility for the event on government negligence. Past state abuses can add a tiny grain of truth to even the most outlandish of conspiracies.

Most importantly, suicide bombings are so traumatic, especially to Western countries, that they create a defensive psychological reaction. Unable to accept that they can be targeted at random, people take comfort in conspiracy theories implicating the government itself.  Ironically, for those who consider themselves opponents of the government, this is a perverse kind of confidence in the competence of their governments to actually carry out successful conspiracies. In contrast, the idea that terrorists armed with boxcutters can kill 3,000 is much more unsettling.

If governments do not immediately give enough information to demonstrate the accuracy of the official version of events, they spawn distrust and divisions within their societies. It may be painful to reveal information that puts the government's response in a negative light. But not doing so creates a conspiracy vacuum.  Even though nothing will convince a hardcore true believer, governments must decisively confront those responsible for propagating conspiracy theories before large swathes of the population accept them.

A healthy distrust of the government is necessary in any democracy. But when a substantial number of citizens believe that their government has either carried out or abetted terrorist attacks against them, it creates the potential for an escalating cycle of paranoia and national division.  Consider Weimar Germany of the inter-war years, when the Nazis declared that Jews, socialists, and liberals had manipulated the German government into humiliating defeat.  And in the modern Arab world, every conspiracy, no matter how trivial, is either blamed on the CIA or Mossad.  In both cultures, politicians, preachers, and terrorists propagate hateful anti-Semitic conspiracies.

Societies in which conspiracy theories become the primary explanations for political events are unhealthy places.  In nations where the public believes anyone who offers a simple and soothing explanation, politicians rise to power by voicing anger against those who “betrayed the people.”  And if those who manipulate the public's rage, fear, and distrust actually gain power, the society faces catastrophic consequences.

Adam Elkus is a freelance journalist. His writings on foreign policy and national security have been published in Foreign Policy in Focus, Peace Magazine, Electronic Iraq, and other websites and journals. This is his first contribution to ON Point.