9/11 was an inside job. The Holocaust is a myth promoted to serve Jewish interests. The shootings at Sandy Hook Elementary School were a false flag operation. Climate change is a hoax perpetrated by the Chinese government. These are all conspiracy theories. A glance online or at bestseller lists reveals how popular some of them are. Even if there is plenty of evidence to disprove them, people persist in propagating them. Why? Philosopher Quassim Cassam explains how conspiracy theories are...