School thesis
Keynesian macro is a theory of demand failure under uncertainty. It matters when planned spending falls short of the income needed to employ available labor and capital.
Keynesian starts from weak aggregate demand can leave the economy stuck below full employment.
Mechanism: spending shortfalls, multiplier effects, and sticky adjustment can create persistent underutilization. Policy instinct: use fiscal and monetary stabilization when private demand collapses.
Use when
Aggregate demand insufficiency, sticky prices and wages, the multiplier and accelerator, and the role of fiscal policy as an active stabilization tool when monetary space is constrained.
Evidence burden
Output gaps open during recessions before policy responds and close after demand-side stimulus rather than spontaneous price adjustment.
Rival check
Recoveries that complete without demand stimulus, with output and employment closing the gap through real adjustment.
Mechanism chain
Claim
Weak aggregate demand can leave the economy stuck below full employment.
Mechanism
Spending shortfalls, multiplier effects, and sticky adjustment can create persistent underutilization.
Policy read
Use fiscal and monetary stabilization when private demand collapses.
Mechanism
The claim needs each step in the data; a missing link weakens the whole interpretation.
Shock
Consumption, investment, or net exports weaken. The first-order object is expenditure rather than technology.
Propagation
One household's spending is another household's income. Layoffs and lower revenues can turn an initial shock into a multiplier process.
Policy
Fiscal and monetary policy are strongest when idle resources exist and private balance sheets are too cautious to restart spending.
Reads the economy through
aggregate demand / employment / stabilization policy
Lineage
Historical moves show which problem the tradition was built to solve and which claim it keeps defending.
1936
Keynes made employment depend on effective demand, liquidity preference, and uncertainty rather than automatic wage-price clearing.
1940s-1960s
IS-LM and multiplier pedagogy compressed Keynes into a teachable policy framework, useful but less rich than the original theory.
Modern use
Current Keynesian work is strongest when it asks how fiscal multipliers change with slack, rates, liquidity constraints, and monetary accommodation.