See also: Myth | Dangerous
Wikipedia: Fallacies of Definition
A persistent misconception or an error in reasoning. The public sphere is full of fallacious conversations, primarily because people remain unaware of much knowledge, but also because some people gain from other peoples lack of understanding or access to accurate information.
This unknown information can be harmful to democracy because fallacies allow actions to be taken which are detrimental to a persons real well-being.
Fallacies can also be exploited for pleasure with various games.