Critical Thinking for Marketers, Volume I

CHAPTER 3

The Nature of Logical Fallacies

This book covers a total of 60 formal and informal logical fallacies. But what distinguishes a formal from an informal logical fallacy? Basically, formal fallacies are errors in reasoning where the form of the argument does not always guarantee a true conclusion, while informal fallacies are reasoning errors in an argument’s content or premises. Let’s unpack what these terms mean.

A formal fallacy is not an error of reasoning made by someone wearing a tux and black tie. Rather, it’s an error of reasoning—intentional or unintentional—attributable to the “form” of a deductive argument, independent of its content. (Recall that a deductive argument is a series of premises and a conclusion where, if the premises ...