Fallacies of definition

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Fallacies of definition refers to the various ways in which definitions can fail to explain terms. The phrase is used to suggest an analogy with an informal fallacy.[citation needed] "Definitions that fail to have merit because they are overly broad, use obscure of ambiguous language, or contain circular reasoning are called fallacies of definition."[1] Three major fallacies are overly broad, overly narrow, and mutually exclusive definitions,[2] a fourth is incomprehensible definitions,[3] and one of the most common is circular definitions.[4][5]


Circular definition of inflammable liquid.[4]

If one concept is defined by another, and the other is defined by the first, this is known as a circular definition, akin to circular reasoning: neither offers enlightenment about what one wanted to know.[6]

A straightforward example would be to define "Jew" as "a person believing in Judaism", and "Judaism" as "the religion of the Jewish people", which would make "Judaism" "the religion of the people believing in Judaism."

Overly broad or narrow definitions[edit]

A definition intended to describe a given set of individuals fails if its description of matching individuals is overly wide or narrow. For example, "a shape with four sides of equal length" is not a good definition for "square", because not only squares have four sides of equal length, rhombi do as well. Likewise, defining a "rectangle" as "a shape with four perpendicular sides of equal length" is not useful because it is too narrow, as it describes only squares.


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.[citation needed] This can lead to circular definitions. Definitions should be defined in the most prosaic form of language to be understood. Failure to elucidate provides fallacious definitions.[6]

An often quoted[citation needed] 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?"[7][clarification needed]

Self-contradictory requirements[edit]

Definitions may fail by imposing conflicting requirements, making it impossible for them to apply to anything at all.

See also[edit]


  1. ^ Gibbon, Guy (2013). Critically Reading the Theory and Methods of Archaeology: An Introductory Guide. Rowman & Littlefield. ISBN 9780759123427.
  2. ^ Potter, Karl H. (1991). Presuppositions of India's Philosophies, p.87. Motilal Banarsidass. ISBN 9788120807792.
  3. ^ Chakraborti, Chhanda (2007). Logic: Informal, Symbolic and Inductive, p.54-5. PHI Learning. ISBN 9788120332485.
  4. ^ a b Hughes, Richard E. and Duhamel, Pierre Albert (1966/1967). Principles of rhetoric/Rhetoric principles and usage, p.77/141. 2nd edition. Prentice-Hall.
  5. ^ Schipper, Edith Watson and Schuh, Edward (1960). A First Course in Modern Logic, p.24. Routledge. Incongruous, circular, negative, and obscure or figurative.
  6. ^ a b "The Logical Fallacies". [full citation needed]
  7. ^ "World's Strangest".