Macroeconomics in a Historical Perspective

Classical and Neoclassical Foundations

• Classical Economists (until late $19th$ century): Smith, Mill, Ricardo, Malthus, and Marx.
• Primarily moral and political philosophers using little to no mathematics.
• Neoclassical Shift (late $19th$ to early $20th$ century): Jevons, Marshall, and Walras introduced mathematical modeling.
• Subject Domain: Defined by Robbins as the relation between objectives and scarce resources.
• Methodology: Focused on rational choice theory and behavioral analysis rather than descriptive fieldwork.

The Keynesian Transformation and Synthesis

• Keynes ($1930s$ Great Depression): Highly innovative with strong policy implications but used minimal mathematics.
• Neoclassical Synthesis (Post-WWII): Combined Neoclassical framework with Keynesian ideas, utilizing mathematical models like $\text{IS-LM}$, $\text{Mundell-Fleming}$, and $\text{AD-AS}$.
• Global Application: These models are used by the IMF, The World Bank, and central banks, though they are often less nuanced than Keynes' original work.
• Heterodox Economics: Emerged as a critical, often marginalized alternative that questions the purported objectivity and ethical neutrality of neoclassical models.

Modern Macroeconomics and the Lucas Critique

• $1970s$ Oil Crises: Led to stagflation ($\text{Stagflation} = \text{inflation} + \text{stagnating economy}$), which neoclassical models struggled to explain.
• Lucas Critique ($1976$): Lucas argued that neoclassical business cycle models were inappropriate for policy evaluation.
• Modern Macroeconomics: Built on rational choice theory with high mathematical and numerical complexity.
• Model Design: Modern models often rely on dubious assumptions to ensure mathematical solvability, sometimes leading to policy implications different from neoclassical synthesis models.

Crisis and Critical Evaluation

• Great Recession ($2007$-$2008$): Modern models failed to foresee the crisis, largely because many lacked a formal banking sector.
• The Lesson of Criticality: Macroeconomic models are useful tools, but their assumptions often lack strong empirical foundations.
• Ideological Bias: Simplifying assumptions used for mathematical convenience may carry significant ideological implications; therefore, models should be evaluated for potential bias.