9 Reasons People Believe In Conspiracy Theories
5. Proportionality Bias
Speaking massive geopolitical upheavals, the Proportionality Bias is probably behind a lot of the large-scale conspiracies regarding events such as the assassination of JFK, or the destruction of the Twin Towers.
The mistake often made here is the assumption that big events are necessarily the result of an equally large cause. It is difficult for people to process the idea that the small actions of the individual can have such enormous consequences.
This is almost simultaneously opposed and related to the feelings of powerlessness we talked about in the last entry, as it feels almost implausible that just one individual, we'll call him Lee Harvey Oswald, would be able to wake up one morning and change the course of history. It somehow feels much more "right" that a huge event has a correlatory huge cause.
As for 9/11, a combination of all the biases we have discussed so far come into play here. The event was world-changing, but orchestrated by a relatively small organisation. The politics surrounding it were startlingly complex and its motivations were not something that most Western minds are familiar with (many people now, if you ask them, will still not be able to tell you what the likes of IS and Al-Qaeda actually want), and so it's much easier in many ways, to blame the powerful, but familiar, American government.