Concerns formal (syllogistic) fallacies, informal (rhetorical) fallacies, tactical misdirection, and errors in logic or reasoning more broadly put.

The term 'fallacy' may refer to:

  • Formal (syllogistic) fallacies: errors in logical validity rooted in the structure of formal arguments
  • Informal (rhetorical) fallacies: common mistakes or misunderstandings that people make when reasoning
  • Tactical misdirection: the intention misuse of logic or logical structures to present false or misleading impressions
  • Errors in logic or reasoning more broadly put

Technically speaking, the term 'fallacy' is restricted to the first (formal) usage, which differs from he others because it is a function of the underlying structure of logic, independent of the truth or falsehood of given premises. But colloquially the term has been expanded to mean poor reasoning of any sort.