DEMOGRAPHY. — In the broad sense, this is the application of statistical, that is, quantitative, methods to population phenomena: it thus consists fundamentally in methods considered fruitful or which are, in any case, widely employed in the quantitative study of demographic phenomena (birth rate, mortality, nuptiality, migration, etc.).
The investigative character of d. is expressed in the study and investigation of the laws, that is, of the statistical regularities, which the biological and social morphology and functions of the population may display: study and investigation that are generally the work of the scholar, conducted on data today predominantly collected, processed, and presented by national and international statistical bodies according to a technique that distinguishes between the state of the population and the movement of the population.
The study of the state of the population, that is, of its numerical size at a given moment, of its internal composition according to individual characteristics and in relation to a given territory, is served principally by censuses: grandiose demographic inquiries which, formerly conducted at irregular intervals, in modern times are carried out in civilized countries at equal intervals of time, encompass the entire territory of a State and all the persons inhabiting it at a given moment. They thus possess three principal characteristics: periodicity, universality, and simultaneity.
From the original statistics of the population at a given moment—for example, the number of persons living—it is easy to derive other data, consequently called derivative, which likewise represent a current state of affairs, such as masculinity, that is, the ratio of the number of males to that of females at the time of the census.
The movement of the population consists in the pro-
cess of variation in the state of the population as a consequence of movements: a) internal: births and deaths; b) external: migrations into and out of the country. It is only in these that the direct active and passive elements are identified, from whose balance the demographic equilibrium of the country results: hence they are also called constitutive variations.
A distribution of the living population is the effect of the combined operation of birth rates, mortality, and migratory movements. Evidently, the boundaries assigned to the expression “movement of the population” are crossed when one follows the practice of statistical sources of placing, alongside internal movements, certain events (marriages, divorces, legitimations, and so forth) that modify the essence of the qualitative, juridical-social relations of the members of the observed community, while leaving it quantitatively unchanged. The origin of this practice is to be sought in the common use of the so-called civil-status registers and of the bodies—civil-status offices—ordinarily official in character, which undertake the collection of quantitative and qualitative variations.
Now, d., in more general terms than those previously established, investigates the position and resolution of statistical problems concerning the biological and social form and activity of human collectivities: problems which, broadly speaking, may be viewed from a twofold standpoint, namely, by considering population phenomena in their global manifestations, or by seeking to understand them as the overall effect of a set of elementary circumstances residing in the qualities and properties of individuals. In practice, there is nothing absolute in demographic inquiries: dynamic data (proper to the civil-status services) are often used jointly with static data (obtained through censuses: operations of extremely ancient origin, initially serving fiscal and military purposes, or, later, when the Milanese councils under s. Carlo Borromeo prescribed the periodic compilation of the religious “states of souls”).
Direct and indirect methods subsequently devised for calculating the population in intercensal intervals are often applied with considerable adaptations, varying especially according to the hypotheses adopted concerning the law governing the variation of the population between two successive known states.
By then extending (through appropriate extrapolative procedures) into the future the trends in birth rates and mortality ascertained in the past for population groups selected according to age and sex—ascertained in the more or less recent past according to the length of the future to which the forecasts are to be extended—hypothetical data are obtained concerning the total size and composition of populations in the future. The forecasts are, obviously, variously reliable according to the hypotheses adopted, and these vary greatly as a function of demographic dynamics, which often differ considerably from one country to another (progressive, regressive, and stationary populations).
Yet, whatever the characteristics of development of the various populations, it is now an established fact in demographic investigations—both microscopic, that is, concerning populations of relatively small territories, and macroscopic, that is, concerning populations of comparatively extensive territories—that the fundamental coefficients of demographic dynamics, namely birth-rate and mortality coefficients, decline over time: from the difference between them in successive intervals of time results the rate of development of a population.
But since the range of variation of the birth rate is broader than that of the mortality rate (the birth rate may even be equal to zero in the event of the full application of contraceptive practices to procreation; mortality cannot fall below the limit imposed by the nature of the human organism), during the last century, while the mortality rate has fallen considerably as a result of improvements in hygiene, public health, therapeutics, etc., the birth rate has fallen much more markedly because of the ever-wider resort to the voluntary limitation of offspring (which, according to some, would be accompanied by a depression of the reproductive capacity of the species): ultimately, one is witnessing an ever-smaller annual excess, in absolute figures, of births over deaths in the most diverse countries of the world, particularly in the countries of Western Europe.
The German G. P. Süssmilch (1707–67), the Italian G. M. Ortes (1713–90), and the Englishman T. R. Malthus (1766–1834) constructed the core of a system of criteria for studying the development of populations founded upon a divine order and upon human factors capable of supporting it (the spacing or postponement of marriages and chastity): so that equilibrium might be ensured between population growth and the growth of the means of subsistence, and the otherwise inevitable misery might be overcome.
With a not always involuntary moral degeneration of this complex of principles (especially through the degeneration of the principle contained in Malthus’s propositions), an attempt has been made to legitimize the widespread practice of controlling conception or, finally, birth control (as is clearly evident from the decline over time in the fertility of married women and from the ever-greater spread of the voluntary limitation of offspring from the higher social strata to those less well endowed economically and professionally). Thus demographic dynamics evolve with variations clearly smaller than those of economic dynamics, and a serious economic-demographic imbalance is being brought about, the fruit of what has been called the “philosophy of fear”—that is, concern over an imbalance between the rate of population growth and that of the growth of subsistence, in the sense that the development of the latter might not permit the development of the former. Alongside a systematic decline in the overall population of the various countries, this philosophy is leading above all to a thinning of the economically active population and, with the aging of populations, to an aggravation of the social burden on the economically active groups as a result of the growing number of the elderly, that is, the economically inactive.
The enfeeblement of vitality, as an examination of the birth rate in the various French departments and the different Italian regions would seem to bring to light, is the fruit of the diminished strength of the religious and moral sense in certain territories.
When religion does not support people in bearing the burden of offspring, woman recoils from motherhood and man from the cares of the domestic hearth. From this point on, people think less of the future than of themselves, less of self-improvement than of enjoyment, and every ambition requiring energy is extinguished. Life declines in tone; it is reduced to the love of material things, and one ends by forgetting that the continuation of the species is a divine art. In order to live, that is, one loses the reason for living: «et propter vitam vivendi perdere causas».