What Is a Conspiracy Theory and Why Does It Matter?

ABSTRACT Growing concern has been expressed that we have entered a “post-truth” era in which each of us willfully believes whatever we choose, aided and abetted by alternative and social media that spin alternative realities for boutique consumption. A prime example of the belief in alternative realities is said to be acceptance of “conspiracy theories”—a term that is often used as a pejorative to indict claims of conspiracy that are so obviously absurd that only the unhinged could believe them. The epistemological standard often involved in this indictment, however—the standard of “obvious” falsity—invites subjectivity in its application, because what is obviously false to one person can be common sense to another. This is not just a truism; considerable research suggests that people’s political beliefs, in general, and their acceptance or rejection of conspiracy theories in particular, tends in large part to be determined by partisan, ideological, and other priors.