It has been suggested that this article or section be merged into Formal fallacy. (Discuss) Proposed since April 2012.

Fallacies of definition refer to the various ways in which definitions can fail to have merit. The term is used to suggest analogy with the logical fallacies.

  Circularity

If one concept is defined by another, and the other is defined by the first, this is known as circular definition, somewhat similar to a circular reasoning: neither offers us any enlightenment about what we wanted to know.^[1]

  Broad definitions

A definition is no good if it defines its subject with overly wide parameters. For example, suppose the word square is defined by "A figure is square if and only if it has four sides of equal length." It is true that all squares have four sides, but 'square' is not a good definition for 'a shape with four sides'. Why? Not only squares have four sides of equal length; trapezoids do as well. This is proven by identifying not only the term being defined, but also the conditions in the definition. ^[2]

  Obscurity

Definitions can go wrong by using ambiguous, obscure, or figurative language. If 'beauty' is defined as 'aesthetically successful', one must continue to break down and define the following definition. This can often lead to circular definitions. Definitions should be defined in the most prosaic form of language to be understood. Failure to elucidate provides fallacious definitions.^[3]

An often quoted example is Samuel Johnson's definition for oats: "Oats: a grain which in England is generally given to horses, but in Scotland, supports the people", to which his Scots friend, Lord Elibank, retorted, "Yes, and where else will you see such horses and such men?"^[4]

  Self-contradictory statements in context

Often statements can contradict themselves due to a difference in definitions while defining something. For example, the statement "A society is free if and only if liberty is maximized and people are required to take responsibility for their actions" is true or paradoxical, depending on the individual's definition of liberty. If liberty is taken to mean "the ability to exercise one's rights as provided for by the law and nature" then this is true, but if it means "the state when one is not held to nor required to perform anything against their will" then this is clearly false. ^[5]

  See also

• Equivocation

  References