Fallacies of presumption are not errors of reasoning in the sense of logical errors, but are nevertheless commonly classed as fallacies. Fallacies of presumption begin with a false (or at least unwarranted) assumption, and so fail to establish their conclusion.


Arguments involving false dilemmas, complex questions, or circularity all commit fallacies of presumption: false dilemmas assume that there are no other options to consider; complex questions assume that a state of affairs holds when it may not; circular arguments assume precisely the thing that they seek to prove. In each case, the assumption is problematic, and prevents the argument from establishing its conclusion.