ch. 10

Key Concepts in Keynesian Economics

  • Keynesian Economics Overview

    • Introduced by John M. Keynes in response to the Great Depression.

    • Challenges classical economics, particularly Say's Law and the idea of a self-regulating economy.

  • Impact of the Great Depression

    • High unemployment (>20%) and economic hardships during the 1920s-30s led to a demand for government intervention.

  • Keynesian vs Classical Economics

    • Classical Economics:

    • Saving is influenced by interest rates.

    • Flexible wages and prices, allowing for natural adjustment of unemployment.

    • Keynesian Economics:

    • Inflexible wages; resistance to wage cuts.

    • Recessionary gaps won't close without intervention.

    • Emphasizes the need for government fiscal policies.

  • Keynes’s Critique of Classical Economics

    • Questions the assumption that labor and prices can adjust freely downward, suggesting businesses may opt for higher wages.

    • Argues that economies can get stuck in recessionary gaps without intervention.

  • Consumption Function

    • Relationship: C=C<em>0+(MPC)(Y</em>d)C = C<em>0 + (MPC)(Y</em>d)

    • Where MPC = Marginal Propensity to Consume, MPC=ΔCΔYdMPC = \frac{\Delta C}{\Delta Y_d}

    • Autonomous consumption value for households (e.g., $17,594) and average MPC.

  • Marginal Propensity to Save (MPS)

    • Defined as: MPS=ΔSΔYdMPS = \frac{\Delta S}{\Delta Y_d}

  • Multiplier Effect

    • Impact of autonomous spending on total spending and GDP:

    • Multiplier=11−MPCMultiplier = \frac{1}{1 - MPC}.

    • Example: Government spending of $725 billion with an MPC of 0.81 leads to a GDP change of approximately $3.8 trillion.

  • Aggregate Demand in Keynesian Model

    • Total spending (C + I + G) affects the Aggregate Demand curve; consumption changes shift this curve.

  • Keynesian Aggregate Supply

    • Assumes a horizontal supply curve until full employment is reached. Government intervention is essential during recessions.

  • Equilibrium and Recession Gaps

    • The economy can be in a recessionary gap while in equilibrium; private sectors may be insufficient for recovery.

    • Government plays a critical role in economic management during downturns.