Many technical analyses cast doubt on the official explanation of the collapse of three World Trade Center buildings, including those presented by an impressive new group: Architects and Engineers for 9/11 Truth. More difficult than discovering the truth, however, is convincing most of the public to accept the bitter truth.

Americans easily block out painful truths. Powerful societal forces keep much of the population distracted and uninterested in complex issues. Entertainment-oriented mainstream media contribute to mass ignorance. And the political establishment often buries the truth, uses propaganda and manipulates citizens. Intelligent, strong-willed people can fight all these.

But on a deeper level, many truths are blocked psychologically, because they produce too much pain. This results when truths sharply disagree with strongly held beliefs. The conflict produces cognitive dissonance that can block full acceptance of the disturbing truth. People fall victim to self-manipulation and self-delusion. Truths are dismissed and false beliefs remain embedded.

When it comes to 9/11, we face the strong belief that only Al-Qaeda caused 9/11. But analyses by many experts reveal the collapse of three WTC buildings was not caused by the two airplanes exploding into the two towers. Without getting into details that one can spend many hours examining on a number of websites, the general view is that the buildings were brought down by controlled demolition.

If correct -- IF -- the immediate reaction is like a cosmic big bang. It would have taken considerable effort by a number of people with expertise and access to the buildings to rig them so that they could be intentionally collapsed when the two jets hit the towers. Tough questions flood in: Who could have engineered all this? Could foreign agents accomplish such complex actions -- and if they did, why not take credit for it? If Americans did it, why would they intentionally inflict inevitable mass death and devastation? Worse, they seemingly knew about the plan to fly the jets into the towers.

Post-9/11, why have the government and official investigations not come to the same controlled demolition conclusion? This might be explained if the government was involved.

Pull one string and the whole 9/11 story unravels as your imagination triggers unending questions. Can Americans support a reinvestigation and rethinking of the 9/11 event? Or would they rather avoid even more pain and preserve the official account that places all blame on Al-Qaeda? So easy to criticize those who offer different explanations as conspiracy nuts.

After all, the new truth would be so shocking that we would have to question our political and government system. Could there have been such malevolence somewhere in our government? Did a monumental conspiracy push us into attacks on Afghanistan and Iraq? Did petroleum and corporate interests shape 9/11?

Like other groups, Architects and Engineers for 9/11 Truth wants a new, honest and comprehensive study that considers all the evidence for controlled demolition. First, let the technical truth emerge. Then, if necessary, cope with the inevitable political, conspiracy and other questions. But let us not allow a possible painful truth block the primary task of determining once and for all what caused the collapse of the WTC towers and building no. 7.

If there were non-Muslim forces -- possibly U.S. government ones -- that played a major role in the WTC catastrophe, then let us have the courage to face the truth. Suppose some element of our government played a secret, awful role. If we do not uncover it, then we are vulnerable to repeat nefarious and unimaginable activity in the future -- possibly to impact the 2008 presidential election. Discovering 9/11 truth would enshrine the wisdom of the old adage: the truth hurts. That means suffering the pain of revealing lies and cover-ups. Mourning over the deaths of building victims and heroic first responders would expand with new anger. And another reason to hate and oppose the Iraq war would surface.

If those who believe the official 9/11 story -- especially elected officials -- trust their views, then let them support a serious investigation to test the validity of the controlled demolition hypothesis. If they fear and reject doing so, then let us see that as suspicious and unacceptable.

As a former engineering professor with growing skepticism about the official WTC story, I joined Architects and Engineers for 9/11 Truth; you can learn about the controlled demolition findings and other similar truth-seeking efforts at www.ae911truth.org. You choose: seek the truth yourself or take the easy way and just criticize those who question the official story.

To sum up, horrific possible answers can cause us to shun a question. But clearing our minds of fears of painful truths is essential to clearing our nation of destructive lies. Otherwise, we stay stuck in a delusional democracy.

Joel S. Hirschhorn was a full professor at the University of Wisconsin, Madison, and a senior staffer at the Congressional Office of Technology Assessment and the National Governors Association. He is the author of "Delusional Democracy -- Fixing the Republic Without Overthrowing the Government" a