Chapter 34 — Development Economics

Poverty, Aid, and the World's Poorest Countries

This is the new chapter added to Part VIII — the chapter that a textbook for global readers needs but that many introductory textbooks treat as an afterthought. About 700 million people live in extreme poverty (less than $2.15/day in 2017 PPP). About 3.5 billion — nearly half the world — live on less than $6.85/day. The question of why they are poor and what can be done about it is one of the most important questions economics can address.

Chapter 25 introduced the growth framework (Solow model, institutions, Acemoglu-Robinson). This chapter applies that framework to the specific challenges of the world's poorest countries and introduces the empirical revolution that has transformed development economics: the use of randomized controlled trials (RCTs) to test what actually works.

34.1 Measuring poverty

Extreme poverty: the World Bank's international poverty line is $2.15/day (2017 PPP). About 700 million people (about 9% of the world population) live below this line. The share has fallen dramatically — from about 36% in 1990 to 9% in 2024 — one of the greatest achievements in human history.

The progress is real but uneven. Most of the decline is concentrated in East and South Asia (especially China and India). Sub-Saharan Africa has seen much less progress — the poverty rate has fallen, but the absolute number of extremely poor people has barely changed because of population growth.

Relative poverty is measured within a country — typically as the share of the population below some fraction of the median income. Rich countries have almost no extreme poverty but substantial relative poverty.

34.2 Three theories of underdevelopment

1. Geography (Sachs)

Jeffrey Sachs argues that geography is the primary constraint: tropical climates reduce agricultural productivity, foster disease (malaria, parasites), and make infrastructure expensive. Landlocked countries face higher trade costs. Arid regions face water scarcity.

Evidence for: tropical countries are poorer on average; malaria alone reduces GDP growth by about 1 percentage point per year in heavily affected countries; landlocked countries trade less.

Critique: geography is hard to change, but some tropical countries are rich (Singapore, Botswana) and some temperate countries are poor (Moldova, North Korea). Geography sets constraints but doesn't determine outcomes.

2. Institutions (Acemoglu-Robinson)

From Chapter 25: inclusive institutions (property rights, rule of law, broad access) drive growth; extractive institutions (concentrated power, corruption, weak rights) trap countries in poverty.

Evidence for: the natural experiments (North/South Korea, colonial settler mortality) strongly support the institutional view. Cross-country regressions consistently find that institutional quality is the strongest predictor of income.

Critique: institutions are endogenous — they are shaped by history, geography, and culture. Telling a poor country to "get better institutions" is easier said than done.

3. Colonial legacy (historical)

The slave trade, colonial extraction, and artificial borders drawn by colonial powers created lasting damage: depleted human capital, extractive institutional structures, ethnic fragmentation along colonial administrative lines, and resource-extraction economies that never transitioned to broad-based development.

Evidence for: former colonies with more extractive colonial regimes are poorer today. Countries subjected to the Atlantic slave trade show persistently lower trust and economic development. The arbitrary colonial borders of Africa fragmented ethnic groups and forced unrelated groups into the same state, contributing to civil conflict.

The honest synthesis: all three contribute. Geography sets the baseline constraints. Colonial history shaped the institutions. Institutions determine the current trajectory. Any serious development strategy has to address all three — not just one.

34.3 Aid: does it work?

The Sachs-Easterly debate is the defining dispute in development policy.

Jeffrey Sachs (The End of Poverty, 2005): argues that a "big push" of well-targeted aid — funding health systems, infrastructure, education, agriculture — can break the poverty trap and launch self-sustaining growth. He led the Millennium Villages Project, which provided comprehensive aid to selected villages in Africa.

William Easterly (The Elusive Quest for Growth, 2001; The White Man's Burden, 2006): argues that top-down aid programs rarely work because they ignore local conditions, create dependency, fuel corruption, and substitute outsiders' priorities for local priorities. He argues for "searchers" (local entrepreneurs and innovators finding solutions) over "planners" (outside experts imposing blueprints).

The honest middle ground: aid works for some things in some contexts. Specific, well-designed interventions (deworming, bed nets, vaccination campaigns, conditional cash transfers) have strong empirical support. Large-scale aid programs with vague goals ("develop this country") have a much weaker track record. The RCT revolution (§34.4) has been the key to distinguishing what works from what doesn't.

34.4 The RCT revolution

Abhijit Banerjee, Esther Duflo, and Michael Kremer won the 2019 Nobel Memorial Prize for their work using randomized controlled trials (RCTs) in development economics. The approach: treat development interventions like medical treatments. Randomly assign some communities to receive the intervention and some to a control group. Measure the outcomes. Compare.

What RCTs have found works: - Deworming (Kremer): treating children for intestinal parasites dramatically improves school attendance and long-run earnings. One of the most cost-effective interventions ever measured. - Bed nets for malaria (multiple studies): insecticide-treated bed nets reduce malaria transmission by 50–70%. Free distribution works better than subsidized sales (people don't use nets they had to pay for because of sunk-cost neglect in reverse). - Conditional cash transfers (Progresa/Oportunidades in Mexico, Bolsa Família in Brazil): cash to poor families, conditional on children attending school and receiving health checkups. Reduces poverty, improves school attendance and health outcomes. - Microfinance (mixed results): providing small loans to the poor has modest positive effects — helps some borrowers expand businesses — but is not the transformative solution its proponents initially claimed. The average returns to microfinance are modest.

What RCTs have found doesn't work (or works less than expected): - Textbooks alone don't improve learning outcomes (the constraint is teacher quality and student preparation, not materials). - Some microfinance programs produce no measurable improvement in borrower income. - Top-down agricultural extension (sending experts to advise farmers) has mixed results.

The limitation of RCTs: they test specific interventions in specific contexts. They cannot tell you whether a country should democratize, liberalize trade, or reform its constitution. The big institutional questions from §34.2 are not amenable to RCT testing. The RCT revolution has been enormously useful for micro-level policy design but cannot, by itself, answer the macro-level development question.

34.5 Case studies

Bangladesh — one of the most improbable development successes. GDP per capita has roughly tripled since 2000. Garment manufacturing provides employment for millions of women. NGOs (especially BRAC) have built health, education, and microfinance systems at scale. Bangladesh has not followed the East Asian model (no state-directed industrial policy) — it has followed a bottom-up, NGO-heavy, export-driven model.

Rwanda — a complicated success. After the 1994 genocide, Rwanda's economy was in ruins. Under President Paul Kagame, the government has achieved rapid growth, reduced poverty substantially, expanded healthcare and education, and achieved one of the cleanest governance records in Africa. But Rwanda is also politically authoritarian — the growth has been achieved without political freedom. The Rwanda case illustrates the tension between growth and democracy.

Haiti — persistent poverty. The poorest country in the Western Hemisphere. Centuries of extractive colonial history (France, then internal elites), political instability, weak institutions, natural disaster vulnerability, and inadequate international support have kept Haiti trapped.

India — a mixed record. GDP per capita has risen substantially (from $400 in 1990 to $2,500 in 2024). But the gains are unevenly distributed: rapid growth in IT, services, and urban areas; persistent poverty in rural areas and among lower castes. India's democracy is a strength (voice for the poor) and a constraint (reforms are politically difficult in a country of 1.4 billion people with deep social divisions).

34.6 Where this is going

Chapter 35 covers the economics of technology. Chapter 36 covers student debt, housing, and the American Dream. Chapter 37 covers cryptocurrency. Chapter 38 asks what economics can and can't say about the good life.

Key terms recap: extreme poverty — less than $2.15/day (2017 PPP); about 700 million people geography hypothesis (Sachs) — tropical climate, disease, landlocked geography constrain development institutions hypothesis (Acemoglu-Robinson) — inclusive vs. extractive institutions determine long-run outcomes colonial legacy — extractive colonial regimes created institutional damage that persists RCT — randomized controlled trial; the gold standard for measuring what works in development conditional cash transfer — cash to poor families conditional on school attendance and health checkups J-PAL — the Abdul Latif Jameel Poverty Action Lab, founded by Banerjee and Duflo; runs development RCTs worldwide

Themes touched: Tradeoffs (aid vs. trade vs. institutions), Disagreement (Sachs vs. Easterly), Affects daily life (for 700 million people in extreme poverty).