Chapter 13 — The Economics of Inequality

Who Gets What and Why

At Millbrook State University, Professor Elena Vasquez teaches Introduction to Sociology three days a week. She has a PhD from the University of Wisconsin. She has been teaching at MSU for eighteen years. She has published two books and dozens of articles. She is a popular teacher — her course evaluations are consistently in the top 10% of the department.

Professor Vasquez is an adjunct. She is paid $3,200 per course. She teaches three courses per semester — six per year — for a total annual income of roughly $19,200 before taxes. She has no health insurance through MSU. She has no retirement benefits. She has no job security; her courses are assigned semester by semester. She supplements her income by teaching one course at a nearby community college and by freelance editing. Her total annual income, from all sources, is about $38,000.

Down the hall, Professor James Chen teaches Introduction to Economics two days a week. He has a PhD from MIT. He has been teaching at MSU for twelve years. He has published one book and several articles. His course evaluations are good but not exceptional.

Professor Chen is tenure-track. He earns $92,000 per year. He has health insurance, a retirement plan with employer matching, a modest research budget, and the security of knowing that, barring extraordinary circumstances, he will have this job for the rest of his career.

Both are smart. Both are dedicated. Both have doctorates. Both teach at the same institution, in the same building, to the same students. One earns $38,000 and worries about whether she can afford the dentist. The other earns $92,000 and is planning a kitchen renovation.

This is inequality.

It is not the most dramatic example. The gap between a hedge fund manager earning $200 million a year and a fast-food worker earning $22,000 is larger. The gap between the richest person in the world (worth over $200 billion) and the poorest billion people on Earth (living on less than $2.15 per day) is incomprehensibly larger. But the Vasquez-Chen example has a sharpness that the astronomical numbers sometimes lack: here are two people, doing similar work, in the same building, and one earns less than half what the other earns. The gap is not about talent or effort or education. It is about labor market structure, institutional rules, and the historical accident of which fields have tenure-track positions and which don't.

This chapter is about the economics of that gap — and the much larger gaps that characterize the distribution of income and wealth in the United States and around the world. By the end of it, you should be able to measure inequality, identify its causes, evaluate it through three different philosophical lenses, and assess the main policies proposed to address it. You should also understand why the topic is so contested — not because economists don't know the facts, but because the facts alone don't determine the right response.

13.1 Measuring inequality: the Lorenz curve and the Gini coefficient

Before we can analyze inequality, we need to measure it. The two standard tools are the Lorenz curve and the Gini coefficient.

The Lorenz curve

A Lorenz curve plots the cumulative share of income earned by the cumulative share of the population, ranked from poorest to richest.

If income were perfectly equal — everyone earned the same — the Lorenz curve would be a straight diagonal line from (0%, 0%) to (100%, 100%). This is the line of perfect equality.

In reality, the Lorenz curve bows below the diagonal. The bottom 20% of households earn less than 20% of total income (they earn maybe 3–4%); the bottom 50% earn less than 50% (they earn maybe 12–15%); the top 10% earn more than 10% (they earn maybe 30–35%); and the top 1% earns much more than 1% (they earn about 15–20% of total income in the U.S.).

              THE LORENZ CURVE
   Cumulative
   share of
   income (%)
   100 |                                  ●
       |                               ╱╱
       |                            ╱╱
    80 |                         ╱╱
       |                      ╱╱    ← Line of perfect equality
       |                   ╱╱        (45-degree diagonal)
    60 |                ╱╱
       |             ╱╱
       |           ╱╱
    40 |         ╱╱
       |       ╱╱        ← Actual Lorenz curve
       |     ╱╱           (bows below the diagonal)
    20 |   ╱╱
       |  ╱╱
       | ╱╱
       |╱╱_________________________________________
       0    20    40    60    80    100
               Cumulative share of population (%)
               (ranked from poorest to richest)

Figure 13.1 — The Lorenz curve. The more the curve bows below the diagonal, the more unequal the distribution. A perfectly equal society would have a Lorenz curve on the diagonal. A perfectly unequal society (one person has all the income) would have a Lorenz curve that runs along the bottom axis and then jumps to 100% at the very end.

The Gini coefficient

The Gini coefficient is a single number that summarizes the Lorenz curve. It is defined as the area between the line of perfect equality and the actual Lorenz curve, divided by the total area below the line of perfect equality.

• Gini = 0: perfect equality (the Lorenz curve is on the diagonal)
• Gini = 1: perfect inequality (one person has everything)
• Real-world Gini coefficients: typically between 0.25 and 0.65

Some benchmark Gini coefficients for income inequality: - Sweden: ~0.27 (relatively equal) - Germany: ~0.32 - United Kingdom: ~0.35 - United States: ~0.39 (relatively unequal for a rich country) - Brazil: ~0.49 - South Africa: ~0.63 (one of the highest in the world)

The U.S. Gini coefficient has risen substantially since 1980. It was about 0.35 in 1980 and is about 0.39 today. That may not sound like a big change, but in Gini terms it represents a meaningful redistribution of income from the bottom and middle to the top.

Income inequality vs. wealth inequality

Income inequality measures the annual flow of earnings, interest, dividends, and transfers. Wealth inequality measures the stock of accumulated assets — savings, homes, investments, business equity.

Wealth inequality is much larger than income inequality. In the U.S., the top 1% of households hold about 32% of total wealth. The bottom 50% hold about 2%. The Gini for wealth is about 0.85 — far above the income Gini.

Why is wealth inequality so much larger? Several reasons: - Wealth accumulates over a lifetime (and across generations) - The wealthy earn returns on their wealth (capital gains, interest, dividends) that compound over time - Home equity — the largest single asset for most middle-class families — is distributed very unevenly by race and geography - Inheritance allows wealth to pass between generations in ways that income does not

The distinction matters because income and wealth affect well-being differently. A retiree with $50,000 in annual income and $2 million in savings is in a very different position from a young worker with $50,000 in income and $80,000 in student debt. Income data alone misses this.

13.2 What happened: the rise of inequality since 1980

In the United States and most other rich countries, income inequality fell from roughly 1940 to 1980 — a period sometimes called the "Great Compression." Then it rose sharply from 1980 to the present — a period sometimes called the "Great Divergence."

The facts are not in serious dispute. The real debate is about why.

The four leading explanations

Explanation 1 — Skill-biased technical change (SBTC).

Technology has raised the demand for skilled workers (college-educated, technically adept) and reduced the demand for less-skilled workers (those doing routine manual or clerical work). Computers, automation, and AI are complements to high-skill work (they make skilled workers more productive) and substitutes for low-skill work (they replace routine tasks). The result: rising wages at the top (where the demand for skills has increased) and stagnant or falling wages at the bottom (where demand has decreased or where workers compete with machines).

Evidence for: The college wage premium — the gap between what college graduates earn and what high school graduates earn — has roughly doubled since 1980. Workers in occupations requiring high cognitive or technical skills have seen real wage growth; workers in routine occupations have not. The timing matches: the rise of computing and digital technology since the 1980s coincides with the rise of inequality.

Evidence against (or qualifying): SBTC alone can't explain the extreme concentration of income at the very top (the top 1% and top 0.1%). Technology benefits a broad class of skilled workers, but the gains since 1980 have been concentrated among a much smaller group — executives, financiers, tech entrepreneurs. Something beyond SBTC is needed to explain the top of the distribution.

Explanation 2 — Globalization.

Trade with low-wage countries (especially the China shock from Chapter 9) has reduced demand for manufacturing workers in rich countries, pushing down wages for less-skilled workers while benefiting consumers and workers in export industries.

Evidence for: The Autor-Dorn-Hanson work on the China shock shows that communities exposed to import competition experienced wage declines and employment losses. The timing matches: the acceleration of globalization since the 1990s coincides with the widening of inequality.

Evidence against (or qualifying): Trade is a relatively small share of the overall economy — even at its peak, Chinese imports were about 2.5% of U.S. GDP. Trade can explain some of the widening at the bottom but not the concentration at the top. And many countries that are equally open to trade (Sweden, Denmark) have much lower inequality, suggesting that trade is a contributing factor but not the primary cause.

Explanation 3 — Institutional change.

Institutions that compressed wages in the postwar period — strong unions, high minimum wages, progressive taxation, regulated finance — have weakened since 1980. Union membership has fallen from about 30% of the private workforce in the 1950s to about 6% today. The top marginal tax rate was 70% in 1980 and 37% today. Financial regulation was loosened in the 1980s and 1990s, enabling the growth of a highly compensated financial sector. Minimum wages fell in real terms through the 1980s and 1990s.

Evidence for: Countries with stronger unions and more progressive taxation (Nordic countries, Germany) have less inequality than the U.S. The timing of institutional weakening in the U.S. closely tracks the rise of inequality. Cross-country comparisons strongly suggest that institutions matter.

Evidence against (or qualifying): Institutional change is partly endogenous — it's both a cause and a consequence of inequality. Rising inequality gives the wealthy more political power, which they use to weaken the institutions that constrained inequality. Separating cause from effect is hard.

Explanation 4 — Winner-take-all markets.

Some markets have shifted from "many-workers-earn-similar-wages" to "a few superstars earn enormous incomes while everyone else earns much less." This is especially true in entertainment, sports, technology, law, finance, and executive compensation. The mechanism: technology and globalization have expanded the reach of top performers (a tech CEO can reach billions of users; a movie star can reach a global audience), creating returns to being the best that are vastly larger than returns to being second-best.

Evidence for: The distribution of income among top earners has become much more skewed since 1980. CEO-to-worker pay ratios have risen from about 20:1 in 1965 to roughly 300:1 today. Tech billionaires, hedge fund managers, and entertainment superstars account for a growing share of top incomes.

Evidence against (or qualifying): Winner-take-all dynamics explain the top of the distribution but not the bottom. The stagnation of wages for non-college workers is better explained by SBTC and institutional change.

The honest synthesis

Most economists who study inequality believe that all four explanations contribute, but they disagree about the relative importance of each. Some emphasize SBTC (Goldin and Katz). Some emphasize institutions (Piketty, Atkinson). Some emphasize globalization (Autor). Some emphasize winner-take-all dynamics (Frank and Cook).

The disagreement is partly empirical (which mechanism explains the most variance in the data?) and partly about values (how much do you weight the top of the distribution vs. the bottom?). It is not a case where one explanation is obviously right and the others are wrong. It is a case where the real world involves multiple interacting forces, and the relative contribution of each depends on the time period, the country, and the specific question being asked.

Piketty's r > g

Thomas Piketty's Capital in the Twenty-First Century (2013) proposed a sweeping explanation for rising inequality rooted in the relationship between the rate of return on capital (r) and the growth rate of the economy (g). When r > g — when the return on wealth exceeds the rate at which the economy is growing — wealth concentrates over time because the wealthy accumulate faster than the economy grows. Piketty argued that r > g has been the normal state of affairs for most of history (except the mid-20th century, when wars and progressive taxation temporarily compressed inequality) and that we are returning to the historical norm.

Evidence for: Piketty's historical data on wealth concentration is impressive and broadly confirmed by subsequent work. The top 1% share of wealth has risen substantially in the U.S. and Europe since 1980.

Critique: Auten and Splinter (2023), using U.S. tax data, argue that Piketty's estimates overstate the rise of top income shares because of changes in tax reporting behavior over time. The debate is technical and ongoing. The broad direction (inequality has risen) is not in dispute; the magnitude at the very top is.

13.3 Three philosophical frameworks

The facts about inequality are reasonably well-established. The evaluation of those facts is not, because it depends on which values you bring to the question. Economics cannot tell you how to feel about inequality. It can lay out the tradeoffs clearly and help you think about them. Three philosophical frameworks dominate the discussion.

The utilitarian framework

Utilitarianism: the best policy is the one that maximizes total welfare (the sum of everyone's utility).

Utilitarianism applied to inequality produces a straightforward argument for redistribution: if the marginal utility of income is diminishing (an extra $1,000 matters more to a poor person than to a rich person), then transferring income from rich to poor increases total utility. The $1,000 lost by the rich person subtracts less from total welfare than the $1,000 gained by the poor person adds.

The catch: redistribution is not free. Taxes distort incentives (Chapter 7's deadweight loss). Transfer programs have administrative costs and sometimes create perverse incentives (e.g., a benefit that phases out as income rises creates a high effective marginal tax rate for low-income workers, discouraging them from earning more). The utilitarian must weigh the gain from redistribution against the cost of the distortions it creates. This is Okun's "leaky bucket" metaphor: transferring money from rich to poor is like carrying water in a leaky bucket — some value is lost in transit.

How much leakage is acceptable? A pure utilitarian would say: transfer until the marginal gain from redistribution equals the marginal loss from distortion. In practice, this calculation is very hard to make, because it requires knowing the marginal utility of income at different levels, the size of the distortions, and the administrative costs — all of which are uncertain.

The Rawlsian framework

Rawlsianism (John Rawls, A Theory of Justice, 1971): a just society is one organized according to the difference principle — inequalities are acceptable only if they benefit the worst-off members of society.

Rawls asks you to imagine choosing the rules of society from behind a "veil of ignorance" — not knowing whether you will be born rich or poor, talented or not, in a well-off family or a struggling one. From behind the veil, Rawls argues, you would choose rules that maximize the welfare of the worst-off person, because you might be that person. The result is a society that allows inequality only when it creates incentives that make even the poorest people better off than they would be under strict equality.

Example: a Rawlsian might accept that a brain surgeon earns more than a janitor if the higher pay for surgeons creates an incentive for talented people to become surgeons, which improves the quality of healthcare available to everyone, including the poorest. But the Rawlsian would not accept a society where surgeons earn $10 million a year while janitors lack access to basic healthcare — because the inequality is not benefiting the worst-off.

Critique: Critics argue Rawlsianism is too egalitarian (it ignores the welfare of the middle class to focus on the bottom) and too demanding (it asks society to restructure whenever anyone is worse off). Defenders argue it captures a deep moral intuition about fairness.

The libertarian framework

Libertarianism (Robert Nozick, Anarchy, State, and Utopia, 1974): a just distribution is one that arises from voluntary exchanges starting from a just initial position.

Libertarians focus not on the outcome (how much inequality there is) but on the process (how the inequality arose). If you earned your income through voluntary transactions — you offered your labor, someone paid you; you started a business, customers bought from you; you invested wisely — then whatever inequality results is just, because it arose from free choices.

Example: a libertarian might accept a billionaire whose wealth came from building a company that millions of people voluntarily chose to use (Bill Gates, Oprah Winfrey). The inequality is large but it arose from free exchange.

Critique: Critics argue that the "just initial position" condition is rarely met — historical injustices (slavery, colonialism, discriminatory property laws) mean that the starting positions were not just, and inequalities that arise from unjust starting positions are themselves unjust. Defenders respond that you can't undo historical injustices by restricting present-day freedom.

Which framework is right?

This is not a question economics can answer. The three frameworks capture genuinely different moral intuitions: - The utilitarian cares about total welfare - The Rawlsian cares about the worst-off - The libertarian cares about the process

Most people hold elements of all three — they care about total welfare, they have special concern for the worst-off, and they value freedom. The frameworks help you articulate which concern is dominating your thinking in a particular case.

When you read about inequality policies, ask yourself: which framework is the speaker implicitly using? "We should cut taxes to grow the economy" is (roughly) utilitarian. "We should raise the minimum wage to help the poorest workers" is (roughly) Rawlsian. "People should be free to keep what they earn" is (roughly) libertarian. Each position makes sense within its own framework. The disagreement is at the level of values, not facts.

13.4 Four anti-poverty policies

Given the facts and the frameworks, what should we actually do? Four policies are most commonly discussed.

Policy 1 — Cash transfers

Give poor people money. Directly. With no strings attached.

This is the most straightforward anti-poverty policy and increasingly the one that empirical evidence favors. Cash transfers have been tested extensively in development economics (GiveDirectly in East Africa, Bolsa Família in Brazil) and increasingly in rich countries (the expanded Child Tax Credit in 2021, various universal basic income pilots).

Evidence: cash transfers reduce poverty directly and have surprisingly few negative effects on work incentives. Recipients use the money on food, housing, healthcare, and education. The "welfare queens spending it on luxury goods" narrative is not supported by the evidence. The expanded Child Tax Credit in the U.S. in 2021 reduced child poverty by roughly 30% during the months it was in effect.

Tradeoffs: costs taxpayer money; the Okun leaky-bucket concern applies (redistribution creates some distortion); political support is uncertain; the long-run effects on labor supply are debated.

Policy 2 — The Earned Income Tax Credit (EITC)

A wage subsidy for low-income workers, delivered through the tax system. Workers earn income from their jobs; the government supplements that income with a credit that rises with earnings (up to a cap), then phases out gradually. The EITC is the largest federal anti-poverty program in the United States.

Evidence: the EITC has been extensively studied and is widely regarded as one of the most successful anti-poverty programs in U.S. history. It increases both income and labor force participation among low-income workers (because the credit rises with earnings, encouraging work). It has lifted millions of families above the poverty line.

Tradeoffs: the phase-out range creates a high effective marginal tax rate (each additional dollar earned reduces the credit), which can discourage work at higher income levels. The credit is annual (paid in a lump sum at tax time), which limits its ability to smooth monthly cash flow.

Policy 3 — Minimum wage

Raising the wage floor. We covered this in Chapters 6 and 7. The minimum wage is a tool for reducing inequality, but it's an imprecise one — it helps workers who keep their jobs at the higher wage, but it may harm workers who lose their jobs (though the empirical evidence suggests the harm is small for moderate increases). It also doesn't help non-working poor people at all (retirees, disabled people, caregivers).

Most economists see the minimum wage as a useful complement to other anti-poverty tools (especially the EITC), not as a standalone solution.

Policy 4 — Education

Investing in education is the long-run equalizer. The college wage premium exists because college-educated workers are more productive, and investing in education raises the supply of skilled workers, which (over time) should reduce the skill premium and narrow the wage gap.

Evidence: countries with more equal educational attainment tend to have less income inequality. The GI Bill after WWII, which sent millions of veterans to college, was one of the most effective inequality-reducing policies in U.S. history.

Tradeoffs: education takes years to pay off. The benefits accrue to the next generation, not the current one. And not everyone who goes to college benefits equally — the return to college varies enormously by field, institution, and individual circumstances (Chapter 36 will cover this in depth).

13.5 The MSU adjunct story, revisited

Return to Professor Vasquez and Professor Chen. Their wage gap ($38,000 vs. $92,000) is not a mystery to an economist. It is the product of:

• Institutional change. The tenure system has contracted; universities have shifted to contingent labor (adjuncts). In 1975, about 75% of college teaching was done by tenure-track faculty. Today, about 75% is done by adjuncts and non-tenure-track instructors. This is a structural change that reduced the bargaining power and compensation of most college teachers.

• Labor market segmentation. The academic labor market is deeply segmented by field. Economics, business, and STEM fields have outside options (private sector jobs that pay well), which gives tenure-track faculty in those fields leverage to negotiate higher salaries. Sociology, English, history, and humanities fields have fewer outside options, which means universities can pay less.

• Monopsony power. For many adjuncts, the local university is the only employer of their skills. This gives the university wage-setting power similar to the monopsony we'll see in Chapter 21. Adjuncts accept low wages because the alternative is not teaching at all.

• Winner-take-all dynamics. A small number of tenure-track positions are highly compensated and secure. A large number of adjunct positions are poorly compensated and insecure. The distribution looks like a winner-take-all market within academia.

The Vasquez-Chen gap is inequality that the efficiency-equity framework from Chapter 8 can analyze clearly. Is the gap efficient? Maybe — it creates incentives for talented students to enter high-demand fields. Is it equitable? That depends on your framework. A Rawlsian would ask: does this arrangement benefit the worst-off (Professor Vasquez)? The answer is probably no — she would be better off under a system with more equitable pay across academic roles. A libertarian would ask: did Vasquez choose this path voluntarily? Technically yes, but "voluntarily" in a market with severe constraints is a loaded word.

The case study makes inequality personal. It is not about abstract Gini coefficients or national trends. It is about two people, doing similar work, in the same building, earning very different amounts. That concreteness is where the moral force of the inequality discussion comes from — and it is what keeps the topic politically live even when the abstract data gets complicated.

13.6 Where this is going

Chapter 13 is the longest chapter in Part III, and it is the chapter that most directly addresses the efficiency-equity tradeoff introduced in Chapter 8. The four explanations for rising inequality, the three philosophical frameworks, and the four policy responses are the core vocabulary you need for the rest of the book's treatment of distributional questions.

In Chapter 14 (Healthcare), you'll see inequality in access. In Chapter 15 (Climate), you'll see inequality in vulnerability and in the distributional effects of climate policy. In Chapter 21 (Labor Markets), you'll see the labor-side of inequality in much more depth. In Chapter 34 (Development Economics), you'll see global inequality. In Chapter 36 (Student Debt and Housing), you'll see generational inequality. In Chapter 39 (Where Economists Agree), you'll see where the consensus is on inequality and where it isn't.

The efficiency-equity tradeoff is not going away. It is the thread that runs through the rest of the book.

Key terms recap: Lorenz curve — cumulative income share plotted against cumulative population share Gini coefficient — a summary measure of inequality (0 = perfect equality, 1 = perfect inequality) skill-biased technical change (SBTC) — technology raising demand for skilled workers winner-take-all markets — markets where a few superstars earn vastly more than the rest Piketty's r > g — when the return on capital exceeds economic growth, wealth concentrates intergenerational mobility — the extent to which children's economic outcomes differ from their parents' EITC — the Earned Income Tax Credit, a wage subsidy for low-income workers utilitarian — maximize total welfare Rawlsian — maximize the welfare of the worst-off libertarian — evaluate the process, not the outcome

Themes touched: Tradeoffs (efficiency vs. equity, the central tension), Disagreement (about causes and about frameworks), Markets power+imperfect (monopsony, institutional change), Behavioral (loss aversion on relative income), Affects daily life (the Vasquez-Chen gap, the college premium, the poverty line).