Lecture: Population, Urbanization & Social Change
Lecture script · about 15–20 minutes spoken · Week 15
Opening
Picture three people. A city planner is deciding where the next school should go. A nurse is packing boxes to move across the country for a hospital job. A group of tenants is sitting in a hallway, planning how to get their landlord to fix the heat. Each of them runs into the questions in this lecture: how populations grow and move, how cities spread, and how ordinary people organize to change the world around them.
You've been building toward this all along. Week 1 gave you the sociological imagination, the three perspectives, and rates. Week 2 gave you four questions for any figure. Week 3 named cultural lag, Week 13 met Weber's Protestant ethic, and Week 14 asked who holds power. Now those tools meet population and change.
Here's the plan. We'll count people, read a fertility rate, and walk a model of population change. Then we'll watch a city grow and study movements and the engines of change. We'll finish with one real figure about the whole world. This is the last module, so I'll also look back.
1. Count the people
Picture a town council. One member wants a new school, another a senior center. Before they argue, I'd ask them to look at three numbers: births, deaths, and moves.
That's the field in one sentence. Demography is the scientific study of human populations: their size, their makeup, and how they change through births, deaths, and moves. Fertility is childbearing in a population. Mortality is death in a population. Migration is the movement of people into or out of a place.
Counts are hard to compare between towns of different sizes, so you turn them into rates, the move you learned in Week 1. The crude birth rate is the number of live births in a year for every 1,000 people. The crude death rate is the number of deaths in a year for every 1,000 people. And natural increase is the crude birth rate minus the crude death rate: the growth a population gets from births and deaths alone, before anyone moves.
Moves have their own vocabulary. A push factor is a condition that drives people to leave a place, such as a closed workplace, a drought, or danger. A pull factor is a condition that draws people to a place, such as job openings, relatives who can help, or safety. Here's a short story. An illustrative family lives in a coastal town, and the fish-packing plant closes. An inland city has a hospital that's hiring, so the family moves there.
Pause and try this. In that story, what is the push factor, and what is the pull factor?
Sort the reason to leave from the reason to arrive.
Here's the answer. The plant closing is the push, and the hospital jobs are the pull. Most moves have both, so you name each one.
2. Read fertility as a rate
Demographers want one number that sums up childbearing for a whole population. That number is a rate, and it's easy to misread.
Start with the building block. An age-specific birth rate is the number of births in a year to women in one age group, for every 1,000 women in that age group. Then combine them. The total fertility rate is the average number of children a woman would have if she lived through her childbearing years at the current age-specific birth rates. It's synthetic. It imagines one woman walking through this year's rates, age group by age group. No real woman did that.
In the chapter's illustrative country, seven age groups have rates that add to 400 births per 1,000 women. Each group spans five years, so that's 2,000 births per 1,000 women, or 2.0 children per woman. The unit is children per woman, a synthetic average, not a count of any real woman's children.
Now the surprise. A falling rate can come with more births. Population momentum is the tendency of a population to keep growing for decades after its fertility falls, because a large young generation is entering its childbearing years. In the illustrative case, 100,000 women at 100 births per 1,000 give 10,000 births. Then 20 years later, 150,000 women at a lower rate of 80 give 12,000 births. The rate fell. Births rose. Think of a bus where each rider carries fewer bags, but many more riders get on. The luggage rack still fills up.
Pause and try this. A classmate says the total fertility rate of 2.0 in that illustrative country means today's families there have two children. What's the slip?
Think about whose children the rate counts.
Here's the answer. The rate counts no real family's children. It's built from this year's age-specific rates for an imagined woman, so it describes current rates, not family size.
3. Walk the demographic transition
Picture one illustrative country over a long stretch of time. At first, many babies are born and many people die young. Then fewer people die young, while births stay high. Later, families start having fewer children. Finally, births and deaths both settle low.
That story has a name. The demographic transition is a classroom model of a staged path from high birth and death rates, through falling death rates and then falling birth rates, to low and stable rates of both. It's a model. You hold it in one hand, and you don't expect every country to follow it on a schedule.
Here are the chapter's illustrative numbers, per 1,000 people a year. In stage 1, births are 40 and deaths 38, so natural increase is 2. In stage 2, births stay at 40 and deaths fall to 20, so natural increase jumps to 20. In stage 3, births fall to 25 and deaths to 12, for 13. In stage 4, births are 12 and deaths 11, for 1.
Now a different voice. Malthus, in 1798, wrote An Essay on the Principle of Population. He argued that population tends to outrun food. When it does, he said, positive checks, which are famine, disease, and war, raise death rates and restore the balance. I want you to keep Malthus and the transition apart. Malthus predicted the checks. The transition describes what industrial societies did, as their birth rates fell.
Pause and try this. In which illustrative stage does the population grow fastest, and why?
Compare the gap between births and deaths.
Here's the answer. Stage 2. Deaths have fallen to 20 while births are still 40, so natural increase reaches 20 per 1,000, the widest gap of the four.
4. Watch the city grow
Think about the last time you rode a crowded train. You stood close to dozens of people and knew none of them. That's a city way of life, and sociologists set out to explain it.
Urbanization is the growth in the share of a population that lives in cities. The Chicago School was a group of sociologists who studied the city as a kind of ecology. Burgess, in 1925, in "The Growth of the City", offered the concentric-zone model: his classroom model of a growing city spreading outward in rings from the central business district. Picture a dartboard laid over a map, with downtown as the bullseye.
Wirth, in 1938, in "Urbanism as a Way of Life", asked what city life does to people. Urbanism is the way of life that Wirth linked to a city's size, density, and diversity, marked by impersonal and segmented relationships. Segmented means you know most people through one slice of their lives: the driver as a driver, the barista as a barista.
As cities grow, people move to their edges. Suburbanization is the growth of communities at the edge of a city, where more people live and from which many travel into the center.
One honest limit. This course pins no world urban share, because countries define "urban" in different ways. You read that kind of figure at its source, with its year and definition.
Pause and try this. An illustrative city has a wealthy hillside right beside downtown and a factory strip running out along a river. Does that prove Burgess wrong?
Remember what kind of thing his rings are.
Here's the answer. No. The rings are a model, a simplification, and few real cities draw perfect rings. You use the model and then test it against the real city.
5. Tell a crowd from a movement
Two illustrative scenes. In the first, the power fails during a concert, and a crowd of thousands spills into the street, filming and talking, and drifts home within an hour. In the second, a dozen tenants meet every month for three years to press their landlord for repairs. Which one is more likely to change something?
You need two terms. Collective behavior is relatively spontaneous, short-lived action by a large number of people, such as a crowd, a rumor, a fad, or a panic. A social movement is an organized, sustained effort by many people to bring about or to resist change.
So the concert crowd is collective behavior, even though it's huge. The tenants' group is a social movement, even though it's small. The test is organization and staying power, not size. A rumor that sends hundreds of drivers to the gas pumps in one afternoon is collective behavior too, a panic.
Pause and try this. A neighborhood campaign holds meetings, keeps a mailing list, and lobbies the city for bike lanes over several years. Collective behavior or social movement?
Ask whether it is organized, and whether it lasts.
Here's the answer. A social movement. It's organized, with meetings and a list, and it's sustained over years, whatever its size.
6. Sort movements by aim
Some movements want you to change one habit. Others want to remake a whole society. Aberle, in 1966, in The Peyote Religion among the Navaho, sorted movements with two questions. Whom do they aim to change: individuals, or society as a whole? And how much: partly, or totally? Two questions, two answers each, four types.
An alterative movement seeks a partial change in individuals. Alterative is Aberle's own word; courses often say alternative. A redemptive movement seeks a total change in individuals. A reformative movement seeks a partial change in society. A transformative movement seeks a total change in society, and it's often taught as revolutionary.
So a campaign asking people to put their phones away at meals is alterative. A fellowship that asks each new member to leave an old way of life completely is redemptive. The bike-lane campaign, asking for one rule change, is reformative. A movement that seeks to replace a country's whole system of government and ownership is transformative.
Notice what's missing from Aberle's questions. Size. A tiny group can be transformative, and a huge one can be alterative.
Pause and try this. A very large movement asks people to cut back on one everyday habit. Which of Aberle's types is it?
Answer whom, then how much, and leave size aside.
Here's the answer. Alterative. It aims at individuals and asks for a partial change, and its size doesn't enter Aberle's model.
7. Ask why movements rise and how they age
Go back to the tenants. Why did they organize, and why did their campaign last? Sociologists offer several answers, each pointing at a different piece of the story.
Relative deprivation theory says people organize when they feel deprived compared with what they expected or with what others have. The tenants look across the street at a newer building where repairs come fast. Resource mobilization theory, from McCarthy and Zald in 1977, says a movement's success depends on the money, time, people, and organization it can marshal. The tenants collect small dues and run a phone tree. Political process theory says a movement's chances rise and fall with openings in the political system. A new council member who supports inspections opens a door.
Framing, from Snow and Benford in 1988, is the way a movement presents an issue. A diagnostic frame names the problem: the landlord ignores repairs. A prognostic frame offers a solution: an inspection and a repair plan. A motivational frame gives a reason to act: together, every apartment has heat this winter. New social movement theory addresses movements in postindustrial societies organized around identity, quality of life, and values.
Movements also age. The movement life cycle is a commonly taught model: emergence, coalescence, bureaucratization or institutionalization, and decline. Conventions differ on the labels, so hold the idea of stages, not one fixed list.
Pause and try this. Someone says, "Relative deprivation means the poorest people always rebel first." What's the slip?
Ask yourself, deprived compared with what?
Here's the answer. The theory says deprivation is relative. People compare what they have with what they expected or what others have, so the poorest group isn't always the one that organizes.
8. Name the engines of change
Think about how your own neighborhood has changed. A store closed, an app replaced a habit, or a group won a fight. Social change is the transformation of a society's culture, structure, and institutions over time.
You can name four engines that drive it, and you've met three already. Technology: new tools arrive, and norms catch up slowly, the cultural lag Ogburn named. Conflict: Marx read change as struggle between groups over resources. Ideas: Weber argued that a set of ideas, the Protestant ethic, can fit with a new economic spirit. And social movements, the subject of the last three sections.
Now run one illustrative change through three lenses. A neighborhood gets a new rail station. Structural functionalism, at the macro level, reads it as a society adjusting its parts: more workers reach jobs, and transit regains balance. Conflict theory, also macro, asks who wins: owners near the station may profit while renters face higher rents. Symbolic interactionism, at the micro level, watches meanings shift. A place people called far from everything becomes a quick ride downtown. No lens wins. Each answers a different question.
Pause and try this. Which of the three lenses reads the rail station as residents redefining what their neighborhood means?
Think about the micro level, where meanings live.
Here's the answer. Symbolic interactionism. It works at the micro level, where people build new shared meanings for a place.
9. Read the world's fertility figure, then look back
Now one real figure. In Our World in Data's presentation of the United Nations World Population Prospects, the global total fertility rate was 2.3 children per woman in 2023. In the 1950s, it was 4.9. Let's walk Week 2's four questions.
What's measured? The total fertility rate, children per woman at current age-specific rates. Over whom? The world's women in their childbearing years, in 2023 against the 1950s, a decade rather than one year. What does it show? A fall of 2.6 children per woman. That's about 53 percent, more than half, in about seven decades. The 2023 rate is a little under half the 1950s rate. What doesn't it show? Any real family's size, why the rate fell, or that the world's population is shrinking, since momentum can keep a population growing. Correlation or cause? Neither. It's a description, and the demographic transition describes the fall without explaining it.
Pause and try this. A headline says the falling fertility rate proves the world has fewer people every year. What would you tell the writer?
Separate the rate from the count.
Here's the answer. A rate isn't a count. Population momentum can keep a population growing while each woman has fewer children at current rates.
And here's the look back. In Week 1 you met Mills's sociological imagination: reading a private life inside a public pattern. You've done it ever since, with families, schools, congregations, workplaces, and governments, three lenses at a time. This figure is the same move once more. A private choice about children becomes a public pattern across the whole world.
Closing
Let me pull it together. A population changes through fertility, mortality, and migration, and every move has pushes and pulls. The total fertility rate is synthetic, and momentum can bring more births at a lower rate. The demographic transition is a model with four stages, and Malthus predicted checks, which is a different idea. Burgess drew rings, and Wirth described the impersonal city. A crowd is collective behavior; a movement is organized and lasting. Aberle sorts movements by whom and how much they seek to change. Five theories and a life cycle explain how movements rise and age. Four engines drive change, read through three lenses. And the world's rate fell from 4.9 to 2.3 children per woman.
Next in this module come the slide deck, the Readings & Resources page, the lecture tutorial, the practice set, and the quiz, then the discussion, the assignment, and the Sociology in Action Workshop. After that comes the finals week, with the Final Practice Exam and the final. There's nothing new to learn there, only the habits you've built.
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