(principle of) least effort [Zipf's Law]

Glossary of Grammatical and Rhetorical Terms

principle of least effort
“Every individual ," said George Zipf, "when considering a course of action, will choose the action that requires the least amount of effort.". (John Coulter/Getty Images)


The principle of least effort is the theory that the "one single primary principle" in any human action, including verbal communication, is the expenditure of the least amount of effort to accomplish a task. Also known as Zipf's Law, Zipf's Principle of Least Effort, and the path of least resistance.

The principle of least effort (PLE) was proposed in 1949 by Harvard linguist George Kingsley Zipf in Human Behavior and the Principle of Least Effort (see below).

Zipf's immediate area of interest was the statistical study of the frequency of word use, but his principle has also been applied in linguistics to such topics as lexical diffusion, language acquisition, and conversation analysis.

In addition, the principle of least effort has been used in a wide range of other disciplines, including psychology, sociology, economics, marketing, and information science.

See Examples and Observations below. Also see:

Examples and Observations

  • Language Changes and the Principle of Least Effort
    "One explanation for linguistic change is the principle of least effort. According to this principle, language changes because speakers are 'sloppy' and simplify their speech in various ways. Accordingly, abbreviated forms like math for mathematics and plane for airplane arise. Going to becomes gonna because the latter has two fewer phonemes to articulate. . . . On the morphological level, speakers use showed instead of shown as the past participle of show so that they will have one less irregular verb form to remember.

    "The principle of least effort is an adequate explanation for many isolated changes, such as the reduction of God be with you to good-bye, and it probably plays an important role in most systemic changes, such as the loss of inflections in English."
    (C.M. Millward, A Biography of the English Language, 2nd ed. Harcourt Brace, 1996)

  • Writing Systems and the Principle of Least Effort
    "The principal arguments advanced for the superiority of the alphabet over all other writing systems are so commonplace that they need not be repeated here in detail. They are utilitarian and economic in nature. The inventory of basic signs is small and can be easily learned, whereas it asks for substantial efforts to master a system with an inventory of thousands of elementary signs, like the Sumerian or Egyptian, which did what the Chinese, according to the evolutionary theory, should have done, namely give way to a system which can be handled with greater ease. This kind of thinking is reminiscent of Zipf's (1949) Principle of Least Effort."
    (Florian Coulmas, "The Future of Chinese Characters." The Influence of Language on Culture and Thought: Essays in Honor of Joshua A. Fishman's Sixty-Fifth Birthday, ed. by Robert L. Cooper and Bernard Spolsky. Walter de Gruyter, 1991)

  • G.K. Zipf on the Principle of Least Effort
    "In simple terms, the Principle of Least Effort means, for example, that a person in solving his immediate problems will view these against the background of his future problems, as estimated by himself. Moreover, he will strive to solve his problems in such a way as to minimize the total work that he must expend in solving both his immediate problems and his probable future problems. That in turn means that the person will strive to minimize the probable average rate of his work-expenditure (over time). And in so doing he will be minimizing his effort. . . . Least effort, therefore, is a variant of least work."
    (George Kingsley Zipf, Human Behavior and the Principle of Least Effort: An Introduction to Human Ecology. Addison-Wesley Press, 1949)

  • Applications of Zipf's Law
    "Zipf's law is useful as a rough description of the frequency distribution of words in human languages: there are a few very common words, a middling number of medium frequency words, and many low frequency words. [G.K.] Zipf saw in this a deep significance. According to his theory both the speaker and the hearer are trying to minimize their effort. The speaker's effort is conserved by having a small vocabulary of common words and the hearer's effort is lessened by having a large vocabulary of individually rarer words (so that messages are less ambiguous). The maximally economical compromise between these competing needs is argued to be the kind of reciprocal relationship between frequency and rank that appears in the data supporting Zipf's law."
    (Christopher D. Manning and Hinrich Schütze, Foundations of Statistical Natural Language Processing. The MIT Press, 1999)

    "The PLE has been most recently applied as an explanation in the use of electronic resources, most notably Web sites (Adamic & Huberman, 2002; Huberman et al. 1998) and citations (White, 2001). In the future it could be fruitfully used to study the tradeoff between the use of documentary sources (e.g. Web pages) and human sources (e.g. through email, listserves, and discussion groups); since both types of sources (documentary and human) are now located conveniently on our desktops, the question becomes: When will we choose one over the other, given that the difference in effort has lessened?"
    (Donald O. Case, "Principle of Least Effort." Theories of Information Behavior, ed. by Karen E. Fisher, Sandra Erdelez, and Lynne [E.F.] McKechnie. Information Today, 2005)