Parkinson's law is the adage that "work expands so as to fill the time available for its completion".
Articulated by Cyril Northcote Parkinson as part of the first sentence of a humorous essay published in The Economist in 1955, it was reprinted with other essays in the book Parkinson's Law: The Pursuit of Progress (London, John Murray, 1958). He derived the dictum from his extensive experience in the British Civil Service.
A current form of the law is not the one Parkinson refers to by that name in the article, but a mathematical equation describing the rate at which bureaucracies expand over time. Much of the essay is dedicated to a summary of purportedly scientific observations supporting the law, such as the increase in the number of employees at the Colonial Office while Great Britain's overseas empire declined (he shows that it had its greatest number of staff when it was folded into the Foreign Office because of a lack of colonies to administer). He explains this growth by two forces: (1) "An official wants to multiply subordinates, not rivals" and (2) "Officials make work for each other." He notes that the number employed in a bureaucracy rose by 5–7% per year "irrespective of any variation in the amount of work (if any) to be done".
The first-referenced meaning of the law has dominated, and sprouted several corollaries, the best known being the Stock-Sanford Corollary to Parkinson's Law:
If you wait until the last minute, it only takes a minute to do.
Other corollaries include (relating to computers):
Data expands to fill the space available for storage.
Storage requirements will increase to meet storage capacity.
The law could be generalized further as:
The demand upon a resource tends to expand to match the supply of the resource.
An extension is often added:
The reverse is not true.
This generalization has become very similar to the economic law of demand; the lower the price of a service or commodity, the greater the quantity demanded.
Some define the law in regard to time as:
The amount of time that one has to perform a task is the amount of time it will take to complete the task.
Parkinson also proposed a rule about the efficiency of administrative councils. He defined a "coefficient of inefficiency" with the number of members as the main determining variable. This is a semi-humorous attempt to define the size of a committee or other decision-making body at which it becomes completely inefficient.
In Parkinson's Law: The Pursuit of Progress, London: John Murray, 1958 one of the chapters is devoted to the basic question of comitology: how committees, government cabinets, and other such bodies are created and eventually grow irrelevant (or are initially designed as such).
Empirical evidence is drawn from historical and contemporary government cabinets. Most often, the minimal size of a state's most powerful and prestigious body is five members. From English history, Parkinson notes a number of bodies that lost power as they grew:
- The first cabinet was the Council of the Crown, now the House of Lords, which grew from an unknown number to 29, to 50 before 1600, by which time it had lost much of its power.
- A new body was appointed in 1257, the "Lords of the King's Council", numbering fewer than 10. The body grew, and ceased to meet when it had 172 members.
- The third incarnation was the Privy Council, initially also numbering fewer than 10 members, rising to 47 in 1679.
- In 1715, the Privy Council lost power to the Cabinet Council with eight members, rising to 20 by 1725.
- Around 1740, the Cabinet Council was superseded by an inner group, called the Cabinet, initially with five members.
At the time of Parkinson's study (the 1950s), the Cabinet was still the official governing body. Parkinson observed that, from 1939 on, there was an effort to save the Cabinet as an institution. The membership had been fluctuating from a high of 23 members in 1939, down to 18 in 1954.
A detailed mathematical expression is proposed by Parkinson for the coefficient of inefficiency, featuring many possible influences. In 2008, an attempt was made to empirically verify the proposed model. Parkinson's conjecture that membership exceeding a number "between 19.9 and 22.4" makes a committee manifestly inefficient seems well justified by the evidence proposed. Less certain is the optimal number of members, which must lie between three (a logical minimum) and 20. That it may be eight seems arguable but is not supported by observation: no contemporary government in Parkinson's data set had eight members, and only the unfortunate king Charles I of England had a Committee of State of that size.
He also wrote the book Mrs. Parkinson's Law: and Other Studies in Domestic Science.
- Parkinson's law of triviality
- Hofstadter's law
- Jevons paradox
- List of eponymous laws
- Peter Principle
- Snackwell effect
- Student syndrome
- Time management
- Time to completion
- Darwin Award
- Parkinson, Cyril Northcote (November 19, 1955). Parkinson’s Law. The Economist.
- Fowler, Elizabeth M (May 5, 1957). It's a 'Law' now: Payrolls grow. The New York Times.
- O'Sullivan, John (June 2008). "Margaret Thatcher: A Legacy of Freedom". Imprimis (Hillsdale College) 37 (6): 6.
- Pannett, Alan Shalini Sequeira; Dines, Andrew; Day, Andrew (2013). Key Skills for Professionals: How to Succeed in Professional Services. Kogan Page. p. 65.
- Klimek, Peter; Hanel, Rudolf; Thurner, Stefan (14 Apr 2008), "To how many politicians should government be left?", Physics and Society (arXiv), 0804.2202 [physics.soc-ph], "It is often argued – as now e.g. in the discussion of the future size of the European Commission – that decision making bodies of a size beyond 20 become strongly inefficient. We report empirical evidence that the performance of national governments declines with increasing membership and undergoes a qualitative change in behavior at a particular group size. We use recent UNDP, World Bank and CIA data on overall government efficacy, i.e. stability, the quality of policy formulation as well as human development indices of individual countries and relate it to the country's cabinet size. We are able to understand our findings through a simple physical model of opinion dynamics in groups.".
- Parkinson, Cyril Northcote (1957), Parkinson's Law, or The Pursuit of Progress.
- Parkinson, Cyril Northcote, Parkinson's Law.
- Parkinson, Cyril Northcote (November 19, 1955), Parkinson’s Law, The Economist.
- ——— (November 1955), "Parkinson's Law" (PDF), The Economist (Berglas).
- Brimelow, Peter (March 28, 2003) [August 7, 1989], "How Do You Cure Injelitance? C. Northcote Parkinson, the father of Parkinson's Law", Forbes (V dare) 144 (3): 42–3.