Lecture 13 - Monetary and Fiscal Policy Claude Notes
1. Introduction and Roadmap
This lecture applies the AD-AS framework developed in earlier sessions to two central questions in short-run macroeconomics: what causes fluctuations in real economic activity, and how can policymakers respond to them? The analytical strategy is to begin from a position of long-run equilibrium and then perturb the economy with either a demand or supply shock, tracing the dynamic adjustment path of output and prices. From this benchmark we then introduce monetary policy and fiscal policy as instruments capable of shifting the AD curve, before evaluating the effectiveness, limitations and political economy of active stabilisation policy.
The Great Recession of 2008 to 2009 then serves as a case study integrating these ideas into a single coherent narrative.
The lecture sits at the intersection of two paradigms. Keynesian macroeconomics treats short-run fluctuations as departures from full employment driven primarily by demand, justifying countercyclical intervention. Classical and monetarist traditions emphasise self-correcting market mechanisms and the informational and incentive limits of discretionary policy. The AD-AS model is a flexible vehicle that can accommodate either view depending on assumptions about price stickiness and the speed of expectational adjustment.
2. The Long-Run Equilibrium Benchmark
The starting point of the analysis is the intersection of the aggregate demand curve with the long-run aggregate supply (LRAS) curve. At this point three conditions hold simultaneously: output equals its natural rate
The diagram identifies point A as the unique configuration in which all three curves intersect. The vertical LRAS reflects the classical dichotomy in the long run: real output is determined by factor endowments, technology and institutions, not by nominal variables. The upward-sloping SRAS reflects nominal rigidities, sticky wages, or imperfect information that allow output to deviate from
Long-run equilibrium: a configuration in which
3. Demand-Driven Fluctuations
3.1 Mechanism of a Demand Contraction
A leftward shift of the AD curve, triggered by a wave of pessimism, a stock-market collapse, a fall in foreign demand, or a monetary tightening, produces a demand-driven contraction. In the short run output falls below
The figure depicts the canonical three-stage adjustment. The economy begins at A on the LRAS, AD shifts from
The movement from A to B is not a shift of SRAS but a movement along it. The crucial reason is that
Do not confuse a movement along SRAS with a shift of SRAS. The initial response to an AD shock is a slide along the existing SRAS curve. The shift of SRAS is the slow, expectations-driven adjustment that restores the natural rate.
3.2 The Deflationary Character of Demand Shocks
A demand-driven contraction is inherently deflationary: prices fall (or rise more slowly) and output falls. This co-movement of prices and quantities is the diagnostic signature of a demand shock and contrasts sharply with the supply-driven case below. In policy terms, deflation combined with falling output makes the case for stimulus particularly compelling because there is no inflation-output trade-off to navigate.
When asked to identify whether a recession was demand-driven or supply-driven, examine the price level. Demand recessions exhibit falling output and falling prices; supply recessions exhibit falling output and rising prices. This is the cleanest empirical fingerprint.
4. Supply-Driven Fluctuations
A leftward shift in SRAS, caused by a sudden rise in production costs (such as an oil price shock) or an upward revision of price expectations, produces an aggregate supply driven contraction. Output falls while the price level rises, a combination known as stagflation. With time, if the underlying cost shock is transitory, SRAS will return to its original position and the economy will revert to
Stagflation was a major theoretical challenge in the 1970s because the simple Phillips Curve, which posited a stable inverse relationship between inflation and unemployment, could not accommodate simultaneously rising prices and unemployment. Friedman and Phelps's expectations-augmented Phillips Curve resolved the puzzle by introducing
Supply shocks are particularly painful because they confront policymakers with a dilemma. Stimulating demand to fight unemployment worsens inflation; tightening to fight inflation worsens unemployment. There is no policy lever that simultaneously addresses both arms of stagflation in the short run.
4.1 Historical Examples
The 1970s oil crises are the textbook case of supply-driven contractions, with OPEC-induced increases in crude prices feeding through to producer costs across the industrialised world. By contrast, supply-driven expansions are harder to identify, but the IT-driven productivity boom of the 1990s is a plausible candidate, since rapid technological progress in computing arguably shifted SRAS (and indeed LRAS) outwards.
The interwar Great Depression provides the canonical demand-driven contraction: real GDP fell by roughly 27%, unemployment rose from 3% to 25%, prices fell by 22%, and the money supply contracted by 28%. The simultaneous fall in output and prices is the hallmark of a demand collapse, and the monetary contraction (associated by Friedman and Schwartz with the Federal Reserve's failure to act as lender of last resort) is widely regarded as the principal cause. Conversely, the early 1940s wartime expansion shows the symmetric case: a positive demand shock from military expenditure drove unemployment from 17% to 1% with prices rising 20%.
5. Accommodating Adverse Supply Shocks
A central policy question is whether to "accommodate" an adverse supply shock by shifting AD rightwards. The trade-off is sharp: accommodation prevents the short-run drop in output but locks in a permanently higher price level.
The slide formalises the choice. Following the leftward shift of SRAS from
Accommodation is controversial because of credibility. If a central bank with an inflation target accommodates supply shocks, agents may rationally infer that the target is soft, embedding higher inflation expectations and shifting the SRAS leftwards persistently. This is why modern inflation-targeting frameworks tend to "look through" temporary supply shocks rather than accommodate them. The 1970s experience taught policymakers that repeated accommodation can entrench stagflationary expectations.
A clean essay on supply shocks should articulate three points: (i) the short-run stagflationary outcome, (ii) the long-run self-correction via expectations, and (iii) the accommodation trade-off between output stabilisation and permanent price-level increases. Mention credibility and expectational anchoring to score the highest marks.
6. Monetary Policy and Aggregate Demand
6.1 The Liquidity Preference Channel
Monetary policy is the first instrument by which AD can be shifted. An expansion in the money supply lowers the equilibrium nominal interest rate, which (since the interest rate is the cost of borrowing) raises investment demand, durable consumption and interest-sensitive expenditures. The result is a rightward shift of the AD curve at any given price level.
Panel (a) shows the money market: the Bank of England shifts money supply from
Think of money supply expansion as flooding the bond market: the central bank buys bonds, their price rises, their yield (the interest rate) falls, and lower yields make every interest-sensitive expenditure more attractive. Consumption of cars and houses rises, firms invest more, and the currency tends to depreciate, boosting net exports. All three channels expand AD.
6.2 Money Supply versus Interest Rates: Two Sides of One Coin
In practice central banks rarely target a quantity of money. They set a policy interest rate (the repo rate, refinancing rate, or discount rate) and conduct open market operations (OMOs) of whatever size is needed to enforce that target. Economically, however, the two operating procedures are isomorphic: setting an interest rate target endogenously determines the money supply, and vice versa.
The choice between targeting the money supply or the interest rate is a Poole (1970) problem. If shocks predominantly hit the money market (LM curve), interest rate targeting is more stabilising. If shocks predominantly hit the goods market (IS curve), money supply targeting performs better. Most modern central banks have settled on interest-rate targeting because money demand has proven empirically unstable, making monetary aggregates unreliable instruments.
- Expansionary monetary policy:
- Contractionary monetary policy:
- In practice central banks set
7. Fiscal Policy and Aggregate Demand
Fiscal policy operates through changes in government spending and taxation. Expansionary fiscal policy (higher
7.1 The Multiplier Effect
A £20 billion increase in government purchases initially shifts AD rightwards by £20 billion. The recipients of this expenditure (workers, contractors, firms) experience an income gain and spend a fraction of it, generating second-round consumption. Firms anticipating stronger demand may raise investment (the investment accelerator). Each round adds to AD, producing a total shift larger than the initial £20 billion.
The figure shows the cumulative effect. The initial shift to
The simplest closed-economy multiplier is
The multiplier is larger when the recipients of fiscal expansion are liquidity-constrained households with MPC near 1. This is why targeted transfers to low-income households or unemployment benefits typically have higher multipliers than tax cuts for high-income earners, who tend to save a larger fraction of windfall income.
Marginal propensity to consume (MPC): the fraction of an additional unit of disposable income that a household spends rather than saves. Higher MPC implies larger spending multipliers.
Do not assume the multiplier applies only to fiscal policy. Any autonomous £1 increase in
7.2 The Crowding-Out Effect
The countervailing force is crowding out. As government spending raises aggregate income, money demand rises (transactions demand for money is income-elastic). With a fixed money supply, this drives up the equilibrium interest rate, which depresses private investment and partially offsets the initial fiscal stimulus.
Panel (a) shows the money market response: money demand shifts from
The strength of crowding out depends on the slopes of the IS and LM curves and on whether monetary policy "accommodates" the fiscal expansion. If the central bank holds the interest rate constant (perfectly elastic LM, as at the zero lower bound), there is no crowding out and the full multiplier applies. If LM is steep and the economy is near full employment, crowding out can be near-total. This is why fiscal multipliers are estimated to be much larger in deep recessions than in normal times.
The net effect of expansionary fiscal policy on AD is the multiplier effect minus the crowding-out effect. Whether £1 of
- the size of the MPC,
- the interest-elasticity of investment,
- the interest-elasticity of money demand,
- the stance of monetary policy,
- the degree of slack in the economy.
When discussing fiscal policy effectiveness, always state both forces explicitly and then identify which dominates in the scenario at hand. In a liquidity trap or zero-lower-bound environment, crowding out vanishes and the fiscal multiplier is at its largest.
7.3 Long-Run Crowding Out
There is a separate, long-run notion of crowding out operating through the loanable funds market. Persistent government deficits absorb private savings, raise long-term real interest rates, and depress private capital accumulation. Unlike the short-run version, this effect is independent of business cycle conditions and accumulates as deficits become chronic.
8. Active Stabilisation Policy
8.1 The Keynesian Case
The Keynesian view stresses that aggregate demand is the principal driver of short-run fluctuations and that nominal rigidities prevent rapid self-correction. Recessions therefore impose avoidable welfare losses through unemployment, hysteresis, and human capital depreciation. The corollary is a moral and economic case for activist countercyclical policy aimed at sustaining full employment.
The Keynesian case rests on three pillars: (i) prices and wages are sticky in the short run, so markets do not clear instantaneously; (ii) the welfare cost of involuntary unemployment is high and asymmetric (job losses hurt more than wage gains help); and (iii) monetary and fiscal instruments are sufficiently powerful to offset shocks. Take any one of these away and the case for activism weakens.
8.2 The Case Against Activism
The opposing view, associated with classical, monetarist and Austrian traditions (epitomised by Hayek and Friedman), raises four objections to discretionary stabilisation:
- Long and variable lags: monetary policy affects output with delays of 12 to 18 months, so by the time stimulus arrives the economy may already be recovering, turning countercyclical policy into procyclical policy.
- Forecast unreliability: stabilisation requires accurate prediction of the output gap, which is notoriously difficult; errors lead to overheating, asset bubbles, and entrenched inflation.
- Political economy distortions: discretionary spending is vulnerable to corruption, capture and electoral cycles, producing systematically biased policy.
- Self-correcting markets: if SRAS adjusts reasonably promptly, the welfare gains from intervention may be small relative to its costs.
The conclusion drawn by sceptics is that policy instruments are better directed at long-run goals (price stability, fiscal sustainability, supply-side reform) than at fine-tuning the cycle.
The lag problem is best understood by analogy: trying to drive a car by looking only in the rearview mirror. If feedback about your position is delayed, attempts to steer can amplify rather than dampen oscillations. This is the essence of the monetarist critique of fine-tuning.
A balanced essay on stabilisation policy should set out the Keynesian case, the monetarist/Austrian counter-case, and conclude with a contingent answer: activism is more justified in deep recessions with clear demand causes and slow self-correction; passivity is more defensible in normal times or when shocks are supply-driven.
9. Case Study: The Great Recession of 2008 to 2009
9.1 The Shock
The 2008 to 2009 financial crisis produced the worst macroeconomic contraction in over half a century at the time. Real GDP fell by approximately 4% between Q4 2007 and Q2 2009, and US unemployment rose from 4.4% in May 2007 to 10.1% in October 2009. The proximate cause was a collapse in financial intermediation: insolvency in the housing-related shadow banking system propagated into a generalised credit freeze, suppressing investment, durable consumption and trade. In AD-AS terms this is a large leftward shift of AD.
9.2 The Policy Response
Three policy actions were deployed, integrating monetary and fiscal levers in a coordinated reflation strategy:
- Conventional monetary easing: Federal Reserve, Bank of England and ECB cut policy rates aggressively, hitting the effective lower bound (close to zero) by late 2008.
- Unconventional monetary policy: with the policy rate constrained, central banks engaged in large-scale asset purchases (quantitative easing), buying government bonds, mortgage-backed securities and other private claims via OMOs to compress long-term yields, repair impaired credit markets, and supply liquidity to banks.
- Fiscal stimulus: in October 2008 the US Congress appropriated $700 billion (TARP) to recapitalise banks via equity injections, with the US and UK governments temporarily acquiring stakes in major institutions. In February 2009 the Obama administration's $787 billion stimulus bill (ARRA) provided a further large fiscal impulse.
The Great Recession illustrates several theoretical points simultaneously. The zero lower bound rendered conventional monetary policy impotent at the margin, justifying quantitative easing as an alternative transmission channel. The proximity to the ZLB also raised fiscal multipliers, because crowding out was muted when the central bank was committed to accommodating fiscal expansion. The episode therefore vindicated the modern Keynesian view that demand management is most powerful precisely when it is most needed.
9.3 Did It Work?
The lecturer's verdict is "arguably yes", tempered by the perennial counterfactual problem: we cannot observe the no-policy scenario. Cross-country comparisons (between economies that stimulated more and less) and structural model simulations broadly suggest the interventions cushioned the downturn meaningfully, though debate continues over magnitudes and side-effects (such as the post-crisis sovereign debt overhang in the eurozone).
Beware of post hoc inference: the fact that recovery followed stimulus does not by itself prove stimulus caused recovery. Sound evaluation requires a counterfactual, typically constructed via structural models or comparative analysis across countries with differing policy responses.
10. Automatic Stabilisers
Beyond discretionary policy, economies possess automatic stabilisers: features of the tax and transfer system that mechanically dampen fluctuations without explicit policy decisions.
Automatic stabilisers: mechanical changes in government revenues and expenditures that cushion aggregate demand over the business cycle, operating without discretionary action.
The principal channels are progressive taxation (tax revenues fall disproportionately in recessions) and unemployment insurance (transfers rise as joblessness rises). Both raise disposable income and AD in downturns and reduce them in booms, smoothing the cycle.
Automatic stabilisers neatly sidestep the lag and forecasting critique levelled at discretionary policy. They activate immediately and proportionally to the shock, requiring no parliamentary decision, no forecast and no political negotiation. This makes them the most reliable countercyclical instrument an economy possesses.
The strength of automatic stabilisers depends on the size and progressivity of the public sector. They are strongest in Scandinavia, weakest in the United States, and intermediate in the United Kingdom. They are not powerful enough to eliminate business cycles entirely, but without them output and employment volatility would be markedly higher.
When asked about the merits of "rules versus discretion", automatic stabilisers offer a powerful synthesis: they provide stabilising effects without requiring discretionary judgment, addressing the Keynesian goal of demand management while sidestepping the monetarist critique of policy errors.
11. Synthesis and Key Takeaways
- The AD-AS framework explains short-run fluctuations as departures from long-run equilibrium driven by shifts in AD or SRAS.
- Demand shocks move output and prices in the same direction; supply shocks move them in opposite directions, producing stagflation.
- In the long run, output reverts to
- Monetary policy shifts AD via the interest rate channel; setting
- Fiscal policy shifts AD by amounts depending on the balance between the multiplier effect (amplification through induced consumption) and the crowding-out effect (offset through higher interest rates).
- The case for active stabilisation policy rests on price stickiness and the welfare cost of unemployment; the case against rests on lags, forecast errors and political distortions.
- Automatic stabilisers provide built-in countercyclical force and partially reconcile the activist and non-activist views.
- The Great Recession illustrated the use of all three policy tools (rate cuts, QE, fiscal stimulus) in tandem, with the zero lower bound enhancing the case for fiscal action.
The most common essay prompts in this area ask you to (i) trace the dynamic effects of a specific shock through the AD-AS model, (ii) evaluate the effectiveness of a specific policy response, or (iii) discuss the rules-versus-discretion debate. Strong answers always combine a clearly labelled diagram, explicit treatment of expectations, and a balanced statement of the multiplier-versus-crowding-out trade-off.
Bibliography
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