John Allen Paulos, a professor of mathematics, writing on Slate, says that confirmation bias isn’t the only reason we believe fake news. Also, the conjunction fallacy, which he describes as making us believe things that have lots of details. As he writes:
The conjunction fallacy posits that we are more susceptible to believing untrue stories if they are more elaborate and specific. The more details there are in a news story… the more plausible and engaging the account might become, albeit less probable.