Demography, Scope, Perspectives and Theory
J C Caldwell
1 November 2000
Demography: Scope, Perspectives and Theory
John C. Caldwell
Health Transition Centre
National Centre for Epidemiology and Population Health
Australian National University
The term “demography” has been widely used in English-speaking countries only from the mid -twentieth century. Earlier, “population studies” or, revealingly, “population problems” had been the common usage. There is still an inclination to restrict “demography” to the analytical methods used to analyze population data while employing “population studies” or “population science” for wider subject matter covering, in addition, the causes and consequences of demographic change. Interest in the size and growth of populations is as old as the first state formations in the ancient Middle East and some attempts to count or estimate population numbers go back millennia. State strength was dependent on population numbers, especially those males of military age, and a good government was one under which numbers increased because of the suppression of violence and success in averting famine. There have long been attempts to place a figure on the number of deaths during severe epidemics. Censuses and the recording of deaths were carried out in some of the citystates of Renaissance Italy. Birth rates were treated as either constant or meaningless and little attempt was made to measure them until shortly before the recent fertility transition.
Modern demography had to await the development of a scientific outlook and counts of population and vital events that were reasonably complete. These conditions began to be realized during the second half of the seventeenth century in Britain, where the Royal Society was founded in 1660 with two of the fathers of demography, John Graunt (1620-74) and William Petty (1623-87) as members. Graunt was a merchant and used bookkeeping principles to construct the first life table, drawing data on 2
mortality from the records of deaths in London, which had been compiled since the previous century. Petty described this activity as “political arithmetic” (Kreager 1988: 134), a term regarded as being so appropriate by Lancelot Hogben that in 1938 he published a book under that title on the demography of contemporary Britain. Edmond Halley (1656-1742) constructed in 1693 a life table much closer to the modern model with more complete data on the deaths and population of the German city, Breslau. Kreager (1991: 209) identifies Graunt, Petty and Halley as the first persons to apply scientific principles to the study of society. All were consciously influenced by the work and scientific principles of Francis Bacon (1561-1626) and were well aware of the value of scientific laws as evidenced by the work of their fellow Royal Society member, Isaac Newton (1642-1727) in his Principia Mathematica (1687) (edited by and published at the cost of Halley). These demographic pioneers’ work bore the same characteristics as those of their successors today.
1. It was dependent on data having come into existence at the whim of others, usually governments, for other purposes (e.g. the London Bills of Mortality were a means of detecting epidemics, principally plague).
2. Much of the labor was spent not on making immediate deductions from the numbers but on suspiciously testing the da ta and trying to improve them. This central assumption that the raw data are almost certainly imperfect sets demographers apart from most social, medical and statistical scientists. 3. Demographers are deeply sensitive to the fact that crude numbers or measures may be misleading, owing to such factors as the age and sex structure of the population, and they are given to devising measures that will overcome the distortions and allow valid comparisons.
4. There is a concept of a population, a large body of people constituting some kind of definable unit to which the measurements pertain.
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