How did modernization theories explain differences between wealthy and poor countries?

Modernization theories, which emerged after World War II, explained the disparities between wealthy and poor countries by framing development as a linear, universal process of transformation from traditional, agrarian societies to secular, urban, industrial ones.12

Key aspects of this explanation include:

• Stages of Growth: Theorists, most notably Walt W. Rostow, argued that all societies must pass through a specific sequence of economic stages. Poor countries were viewed as being at an earlier, "backward" stage of this inevitable development path compared to the industrialized nations of Europe and North America.132
• Factors of Production: Underdevelopment was attributed to internal weaknesses in the factors of production—specifically land, labor, and capital. Modernization was seen as the solution, requiring the dissemination of technology, managerial skills, and entrepreneurship, alongside increased savings and investment.1
• Westernization: The theory implicitly or explicitly held that developing countries should emulate Western economic and political institutions. It envisioned that foreign trade, investment, and aid would serve as the engines of growth, allowing these nations to modernize along capitalist lines.14

While influential, these theories have been criticized for being Eurocentric, ignoring international power imbalances, and failing to account for the diverse paths to development taken by various nations.45