A fallacy is an error in reasoning that results in an invalid argument. Some common examples of logical fallacies are using ambiguous premises, and treating them as if they were unambiguous, circular reasoning (assuming what is to be proved without having derived it from the premises), and jumping to a conclusion (without adequate grounds).

Common Errors

Converse Error

This invalid argument form is called the converse error because the conclusion of the argument would follow from the premises if the premise were replaced by its converse (). This error commonly occurs from a misunderstanding of the modus ponens.

Inverse Error

This invalid argument form is called the inverse error because the conclusion of the argument would follow from the premises if the premise were replaced by its inverse (). This error commonly occurs from a misunderstanding of the modus tollens.