DEMOGRAPHY. — In the broad sense, demography is the application of statistical, i.e., quantitative, methods to the phenomena of population; it is thus fundamentally concerned with methods deemed fruitful or, in any case, widely employed in the quantitative study of demographic phenomena (natality, mortality, nuptiality, migration, etc.).
The investigative character of demography is evident in the study and investigation of the laws, i.e., the statistical regularities, that the morphology and the biological-social functions of a population may exhibit. Such study and investigation, generally the work of the scientist, are conducted on data that are primarily collected, processed, and presented by national and international statistical bodies according to a technique that distinctly distinguishes the state of the population from the movement of the population.
The study of the state of the population, i.e., its numerical size at a given moment, its internal composition according to individual characteristics, and in relation to a specific territory, relies mainly on censuses: large-scale demographic surveys that, while once sporadic, are now conducted at regular intervals in civilized countries, covering the entire territory of a state and all persons residing there 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—e.g., the number of persons living—it is easy to derive other data, known as derivative, which likewise represent a current state of affairs, such as masculinity, i.e., 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 process of change in the state of the population due to movements: a) internal: births and deaths; b) external: migrations in and out. Only these reveal the direct active and passive elements whose balance determines the demographic equilibrium of a country; hence they are also called constitutive variations.
A distribution of the living is the result of the combined interplay of natality, mortality, and migratory movements. Clearly, the boundaries of the expression “movement of the population” are exceeded when, following the customary practice of statistical sources, certain facts (marriages, divorces, legitimations, etc.) are included alongside internal movements. These facts alter the qualitative, juridical-social relationships of the members of the observed community but leave its quantitative size unchanged. The origin of this practice lies in the common use of so-called civil status registers and the offices—usually of an official nature—that handle the recording of both quantitative and qualitative changes.
Now, demography, in terms more general than those previously defined, investigates the position and resolution of statistical problems concerning the form and the biological and social activity of human collectivities. These problems can be viewed *grosso modo* from a dual perspective: either by considering the phenomena of population in their overall manifestations, or by seeking to understand them as the overall effect of a set of elementary circumstances rooted in the qualities and properties of individuals. In concrete demographic research, nothing is absolute: dynamic data (drawn from civil status services) are often used in conjunction with statistical data (obtained from censuses—operations of very ancient origin, initially undertaken for fiscal, military, or, later, religious purposes, as when the Milanese councils under St. Charles Borromeo prescribed the periodic compilation of “status animarum”).
Direct and indirect methods subsequently devised for estimating the population between censuses are frequently applied with certain modifications, especially according to the hypotheses assumed regarding the law of population change between two known successive states.
By extending (through appropriate extrapolative procedures) into the future the trends in natality and mortality observed in the past for population groups classified by age and sex, hypothetical data are derived concerning the overall size and composition of populations in the future. Naturally, the reliability of such projections varies according to the assumptions made, which in turn depend greatly on demographic dynamics—often markedly different from country to country (progressive, regressive, or stationary populations).
Yet whatever the developmental characteristics of different populations may be, a well-established fact in demographic research—whether microscopic, concerning relatively small territorial populations, or macroscopic, concerning comparatively large ones—is the long-term decline in the fundamental rates of demographic dynamics, namely, the birth rates and death rates. The difference between these rates over successive periods yields the growth rate of a population.
However, since the range of variation in the birth rate is wider than that of the death rate (natality can even fall to zero in cases of widespread use of contraceptive practices; mortality cannot fall below the limit imposed by the nature of the human organism), in the last century, while the death rate has markedly declined due to improvements in hygiene, sanitation, therapy, etc., the birth rate has declined even more significantly because of the increasing recourse to voluntary limitation of offspring (which, according to some, is accompanied by a depression of the reproductive capacity of the species). Ultimately, there has been a steady decrease in the annual absolute excess of births over deaths in many countries, particularly in 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 population growth based on a divine order and on human factors capable of supporting it (such as delaying or postponing marriages and celibacy), so as to ensure a balance between population growth and the growth of subsistence resources and to avert the otherwise inevitable poverty.
With a not always unintentional moral degeneration of this complex of principles (especially when the principle contained in Malthus’s propositions degenerates), an attempt has been made to legitimize the very practice of birth control or, in the end, population control (as is clearly evident from the decrease over time in the fertility of married women and from the ever-growing spread of voluntary limitation of offspring from the higher social strata to those economically and professionally less advantaged). Thus demographic dynamics evolve with variations clearly inferior to those of economic dynamics, and a serious economic-demographic imbalance is created, the result of what has been termed the “philosophy of fear,” namely the concern for an imbalance between the rate of growth of the population and that of the means of subsistence, in the sense that the development of the latter cannot allow for the development of the former. It is a philosophy that, alongside a systematic decrease in the overall population of various countries, 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 consequence of the growing number of elderly, that is, economically inactive, individuals.
The weakening of vitality, as an examination of birth rates in the various French departments and Italian regions would seem to indicate, is the result of the diminished strength of the religious and moral sense in certain territories.
When religion no longer sustains the burden of offspring, women shun motherhood and men abandon the cares of the domestic hearth. From this point onward, less thought is given to the future and more to oneself, less to self-improvement and more to enjoyment, and every ambition that demands energy is extinguished. Life is reduced in tone; it is confined to the love of material things, and one ends up forgetting that the divine art is the continuation of the species. In other words, to live is to lose the reason for living: “et propter vitam vivendi perdere causas.”