From 9-11, to the death of Osama bin Laden, to the Boston Bombings, there’s been a consistently bizarre and troubling reaction by some members of the public.

We’re referring to the people—a minority, to be sure, but a surprisingly large one—who always seem to think there’s some kind of cover up. The U.S. government, they feel, was really behind the attacks on, uh, itself. And as for Bin Laden—well, he isn’t really dead.

These people are called conspiracy theorists, and, their particular form of irrationality is uniquely befuddling. It has been often denounced, but rarely understood. That’s too bad, because conspiratorial thinking clearly plays an important role in science denial, on matters ranging from the connection between HIV and AIDS, to the safety of vaccines, to global warming.

Fortunately, conspiracy mongers are now becoming the subject of research and study—and our latest guest is helping to lead this inquiry.

His name is Stephan Lewandowsky, and he’s a professor at the school of psychology at the University of Western Australia, and at the University of Bristol in the UK. And he’s the author of a recent study with the delicious title “NASA Faked the Moon Landings, Therefore (Climate) Science is a Hoax: An Anatomy of the Motivated Rejection of Science (PDF)”—which drew some small amount of attention, especially when it was followed by a second study of the conspiracy theorists who rejected the first study for, yes, conspiratorial reasons.