This article is Version 2. Version 1 can be found here.
First Demographic Transition
The demographic transition is the hypothesized transformation of a society from one of high birth rates and death rates to one of low birth rates and death rates. In The Lonely Crowd (Riesman, Glazer, Denney (1950)), the authors propose a third-phase model of demographic transition, corresponding to three phases of national character broadly. The first phase, called tradition-directed by Riesman, Glazer, Denney (1950), is characterized by high birth rates and high death rates, with population growth possibly restrained by Malthusian pressures. The second phase, called the inner-directed phase, is characterized by falling death rates and birth rates that do not fall as quickly as the death rate, leading to an increase in population. The third phase, called the other-directed phase, is characterized by birth rates that fall as low, or lower than, death rates, leading to stagnation or decrease in the population. The names of the three phases refer to the sources of motivation for the population: from tradition, from one’s inner psychology, and from the norms of others respectively.
The idea of a demographic transition is often considered to have originated with Thompson (1929). In that work, Thompson divides the world’s countries into three groups. Group A consists of those countries with low birth rates and low death rates, generally consisting of Northwest Europe and those countries that were colonized by Northwest European countries. Group B is characterized by declining birth and death rates, but in these countries, the decline in death rates is greater than the decline in birth rates and thus the population growth rate is increasing. Group B consists of generally Southern European countries. Group C includes all countries not in the first two groups, including Russia, India, and Japan. While Group C consisted of 73% of the world population at the time, generalizations about demographic trends are difficult, though these countries generally have high birth rates.
Thompson (1929) does not have a simple explanation for the decline in birth rates in Group A and Group B countries, though he suggests that the proliferation of birth control is a major factor. Thompson observes that the demographic structure of Group B countries is similar to what the structure of Group A countries had been 30-50 years earlier, though he hypothesizes that Group B countries will experience faster birth rate declines due to the more widespread availability of birth control.
Thompson (1929) fears that the population of Group C countries will be limited only by Malthusian pressures, and for this he cites the erratic birth and death rate patterns in India. Furthermore, Thompson notes that, with the exception of Russia, Group C countries may be land-constrained in the foreseeable future, and he fears that they may respond with military conquest.
The concept of a demographic transition was better formalized by Frank Notestein (Notestein (1945) and Notestein (1952)). In Notestein’s formulation, as described by Caldwell (1976), fertility is kept high in premodern societies by religious beliefs, legal structures, and social pressure. Industrialization and modernization weaken these force, allowing families to exercise the “rational” decision of having fewer children. Davis (1955) disputes that large families in low-income countries are irrational, arguing instead that they are rational given the social context.
Caldwell (1976) has questioned the narrative, predominant at the time and still potent, that industrialization and economic development are the drivers of declining birth rates. Anthropologists make four mistakes, according to Caldwell, that offer a misleading picture of the motivation and rationality of high birth rates in less developed countries.
- The flow of wealth is often misunderstood. In particular, anthropologists often fail to observe the flow of wealth from children to parents, done under a sense of duty, which increases the rationality of large numbers of children.
- “Family” is often a survey artifact, grafting Western notions of the nuclear family onto extended families in traditional societies.
- The role of decision making about childbirth, particularly the role of the extended family, is often misunderstood.
- The appeal of modernist values is often taken for granted by surveyors.
Caldwell (1976) finds that in Idaban, a city in Nigeria with a population of around 750,000 at the time, the financial return to parents of a child is greater in urban areas than in rural areas. Caldwell argues that this return, rather than urbanization per se, is the main determinant of family size. He argues that the ideal of the nuclear family and of self-sufficiency–the reluctance to financially assist family members–are Western ideals that are imported into other countries via media rather than the natural products of urbanization, industrialization, and economic development.
Unified Growth Theory
Within development economics, the negative relationship between fertility and economic development is a well-established finding, with Myrskylä, Kohler, and Billari (2005), for example, finding a strong negative relationship between fertility and the human development index. Unified Growth Theory (Galor 2011) presents a mathematical formulation of the relationship between these variables.
The starting point of Galor’s model is that two models govern fertility dynamics in the literature. The first model, which Galor argues held in general among preindustrial human societies, is the Malthusian model, which holds that human population rises until it reaches resource constraints. The second model is the demographic transition, which holds that birth rates generally decline with economic development. Galor’s goal is to develop a unified model which encompasses both observed phenomena, in analogy with the search for a theory in physics that would unify general relativity and quantum theory.
According to Galor (2011), in general preindustrial societies were stuck in a “Malthusian trap”, whereby population growth would absorb all improvements in technology and resource availability, and thus these societies were perpetually near the subsistence level. However, this trap should not be confused for stagnation. Due to Kremerian and Boserupian mechanisms–the latter developed in Boserup (1965), which holds that the actual or perceived threat of resource shortages motivates a society toward technological advancement–preindustrial societies advanced technologically.
As a society industrializes and urbanizes, employers demand a more educated workforce, which induces parents to favor the education of the children over having more children. This effect is known as the quantity/quality tradeoff. According to Galor, the Industrial Revolution is marked as the time when societies escaped the Malthusian trap. There was thus a mutually reinforcing cycle between several factors. Slower population growth allowed a greater share of productivity gains to be channeled into a higher average standard of living, and a more highly educated workforce accelerated growth. In turn, higher growth further motivated parents to reduce their number of children.
The model of (Galor 2011) makes heavy use of mathematics, but it suffers from several shortcomings. The model is based on several stylized facts that are commonly accepted in development economics but which can be debated. Lawson and Borgerhoff Mulder (2016), for instance, question the centrality of the quantity/quality tradeoff in explaining preindustrial fertility patterns. The tradeoff struggles to explain rising rates of childlessness, such as Johnson (2025) documents for the United States. Galor also presents an ambiguous picture of the role of population in driving economic growth, invoking the Kremerian and Boserupian mechanisms to explain preindustrial growth, but also implying that population does not affect overall growth by stating that a larger population implies lower per-capita income.
Second Demographic Transition
The second demographic transition, introduced by Lesthaeghe and van de Kaa (1986), holds that the world, starting with Western European countries after World War II and the Baby Boom, embarked on a process that is distinct from the first demographic transition. Unlike the first transition, the second demographic transition is, as argue Lesthaeghe and van de Kaa (1986), driven by the prevalence of postmodern values that is not reducible to economic conditions. One element in this transition is a shift from materialist to postmaterialist values, such as self-actualization, self-expression, and individual autonomy. Under this transition, marriage is no longer seen as normative but rather as one of several possible life choices. The era of the second demographic transition is thus characterized by an increased prevalent of cohabitation and divorce. The revolutions in postmodern values–effective contraception, the sexual revolution, and the gender revolution in particular–are what Lesthaeghe (2014) believes distinguishes the second demographic transition from the first.
The second demographic transition is, according to Zaidi and Morgan (2017), rooted in what Inglehart (1990) describe as a shift to postmaterialist values in the West. Postmaterialism is, in turned, based in the Maslowian (Maslow (1987)) hierarchy of needs. The hierarchy of needs is, from lowest to highest, physiological needs such as food and water; safety needs such as security and financial stability; love and belonging; esteem; and self-actualization, which includes a sense of meaning and purpose. Maslow argues that the most prepotent needs are at the bottom of the hierarchy, meaning that people will generally pursue the higher needs when the lower needs are fulfilled, though the order is not strictly linear.
Aries (1980), writing of the first demographic transition in the West, refers to the Child-King era in which parents chose to have fewer children so that they could invest greater resources into the upbringing of those children they do have. Thus fertility decline in the first demographic transition was driven by altruistic considerations for the well-being of the children, rather than a downgrading of the perceived importance of child-bearing.
Easterlin (1980) posits that the relative size of a generational cohort determines its well-being, with larger generations facing fewer opportunities than smaller generations. Consequently, Easterlin projects a cyclical pattern in population, with larger generations having fewer economic opportunities and thus fewer children, followed by a smaller generation having greater opportunity and thus more children. By contrast, the second demographic transition, as introduced by Lesthaeghe and van de Kaa (1986) and explained in Lesthaeghe (2014), does not project a fertility rebound when smaller generations come of age.
As Zaidi and Morgan (2017) observe, cohabitation, one of the prominent features of the second demographic transition model, is more prevalent in societies in economic distress, such as in Russia in the 1990s, and among lower-income social classes, suggesting that cohabitation is driven at least in part by economic considerations. They observe that the second demographic transition suffers from a “reading history sideways” fallacy, which treats today’s wealthy countries as being in the past like today’s poor countries and today’s poor countries being in the future like today’s rich countries, and suggest that it is a mistake to model today’s most postmodern wealthy countries as being the endpoint in a unilinear world development process.
References
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