Archive for the 'AD/AS Model' Category

Aug 16 2011

Too much debt or not enough demand? A summary of the debate over America’s fiscal future

As yet another school year begins, we once again find ourselves returning to an atmosphere of economic uncertainty, sluggish growth, and heated debate over how to return the economies of the United States and Europe back onto a growth trajectory. In the last couple of weeks alone the US government has barely avoided a default on its national debt, ratings agencies have downgraded US government bonds, global stock markets have tumbled, confidence in the Eurozone has been pummeled over fears of larger than expected deficits in Italy and Greece, and the US dollar has reached historic lows against currencies such as the Swiss Franc and the Japanese Yen.

What are we to make of all this turmoil? I will not pretend I can offer a clear explanation to all this chaos, but I can offer here a little summary of the big debate over one of the issues above: the debate over the US national debt and what the US should be doing right now to assure future economic and financial stability.

There are basically two sides to this debate, one we will refer to as the “demand-side” and one we will call the “supply-side”. On the demand-side you have economists like Paul Krugman, and in Washington the left wing of the Democratic party, who believe that America’s biggest problem is a lack of aggregate demand.

Supply-siders, on the other hand, are worried more about the US national debt, which currently stands around 98% of US GDP, and the budget deficit, which this year is around $1.5 trillion, or 10% of GDP. Every dollar spent by the US government beyond what it collects in taxes, argue the supply-siders, must be borrowed, and the cost of borrowing is the interest the government (i.e. taxpayers) have to pay to those buying government bonds. The larger the deficit, the larger the debt burden and the more that must be paid in interest on this debt. Furthermore, increased debt leads to greater uncertainty about the future and the expectation that taxes will have to be raised sometime down the road, thus creating an environment in which firms and households will postpone spending, prolonging the period of economic slump.

The demand-siders, however, believe that debt is only a problem if it grows more rapidly than national income, and in the US right now income growth is almost zero, meaning that the growing debt will pose a greater threat over time due to the slow growth in income. Think of it this way, if I owe you $98 and I only earn $100, then that $98 is a BIG DEAL. But if my income increases to $110 and my debt grows to $100, that is not as big a deal. Yes, I owe you more money, but I am also earning more money, so the debt burden has actually decreased.

In order to get US income to grow, say the demand-siders, continued fiscal and monetary stimulus are needed. With the debt deal struck two weeks ago, however, the US government has vowed to slash future spending by $2.4 trillion, effectively doing the opposite of what the demand-siders would like to see happen, pursuing fiscal contraction rather than expansion. As government spending grows less in the future than it otherwise would have, employment will fall and incomes will grow more slowly, or worse, the US will enter a second recession, meaning even lower incomes in the future, causing a the debt burden to grow.

Now let’s consider the supply-side argument. The supply-siders argue that America’s biggest problem is not the lack of demand, rather it is the debt itself. Every borrowed dollar spent by the goverment, say the supply-siders, is a dollar taken out of the private sector’s pocket. As government spending continues to grow faster than tax receipts, the government must borrow more and more from the private sector, and in order to attract lenders, interest on government bonds must be raised. Higher interest paid on government debt leads to a flow of funds into the public sector and away from the private sector, causing borrowing costs to rise for everyone else. In IB and AP Economics, this phenomenon is known as  the crowding-out effect: Public sector borrowing crowds out private sector investment, slowing growth and leading to less overall demand in the economy.

Additionally, argue the supply-siders, the increase in debt required for further stimulus will only lead to the expectation among households and firms of future increases in tax rates, which will be necessary to pay down the higher level of debt sometime in the future. The expectation of future tax hikes will be enough to discourage current consumption and investment, so despite the increase in government spending now, the fall in private sector confidence will mean less investment and consumption, so aggregate demand may not even grow if we do borrow and spend today!

This debate is not a new one. The demand-side / supply-side battle has raged for nearly a century, going back to the Great Depression when the prevailing economic view was that the cause of the global economic crisis was unbalanced budgets and too much foreign competition. In the early 30’s governments around the world cut spending, raised taxes and erected new barriers to trade in order to try and fix their economic woes. The result was a deepening of the depression and a lost decade of economic activity, culminating in a World War that led to a massive increase in demand and a return to full employment. Let’s hope that this time around the same won’t be necessary to end our global economic woes.

Recently, CNN’s Fareed Zakaria had two of the leading voices in this economic debate on his show to share their views on what is needed to bring the US and the world out of its economic slump. Princeton’s Paul Krugman, a proud Keynesian, spoke for the demand-side, while Harvard’s Kenneth Rogoff represented the supply-side. Watch the interview below (up to 24:40), read my notes summarizing the two side’s arguments, and answer the questions that follow.

Summary of Krugman’s argument:

  • Despite the downgrade by Standard & Poor’s (a ratings agency) there appears to be strong demand for US government bonds right now, meaning really low borrowing costs (interest rates) for the US government.
  • This means investors are not afraid of what S&P is telling them to be afraid of, and are more than happy to lend money to the US government at low interest rates.
  • Investors are fleeing from equities (stocks in companies), and buying US bonds because US debt is the safest asset out there. The market is saying that the downgrade may lead to more contractionary policies, hurting the real economy. Investors are afraid of contractionary fiscal policy, so are sending a message to Washington that it should spend more now.
  • The really scary thing is the prospect of another Great Depression.
  • Can fiscal stimulus succeed in an environment of large amounts of debt held by the private sector? YES, says Krugman, the government can sustain spending to maintain employment and output, which leads to income growth and makes it easier for the private sector to pay down their debt.
  • With 9% unemployment and historically high levels of long-term unemployment, we should be addressing the employment problem first. We should throw everything we can at increasing employment and incomes.
  • Is there some upper limit to the national debt? Krugman says the deficit and debt are high, but we must consider costs versus benefits: The US can borrow money and repay in constant dollars (inflation adjusted) less than it borrowed. There must be projects the federal government could undertake with at least a constant rate of return that could get workers employed. If the world wants to buy US bonds, let’s borrow now and invest for the future!
  • If we discovered that space aliens were about to attack and we needed a massive military buildup to protect ourselves from invasion, inflation and budget deficits would be a secondary concern to that and the recession would be over in 18 months.
  • We have so many hypothetical risks (inflation, bond market panic, crowding out, etc…) that we are afraid to tackle the actual challenge that is happening (unemployment, deflation, etc..) and we are destroying a lot of lives to protect ourselves from these “phantom threats”.
  • The thing that’s holding us back right now in the US is private sector debt. Yes we won’t have a self-sustaining recovery until private sector debt comes down, at least relative to incomes. Therefore we need policies that make income grow, which will reduce the burden of private debt.
  • The idea that we cannot do anything to grow until private debt comes down on its own is flawed… increase income, decrease debt burden!
  • Things that we have no evidence for that are supposed to be dangerous are not a good reason not to pursue income growth policies.
  • When it comes down to it, there just isn’t enough spending in the economy!

Summary of Rogoff’s argument:

  • The downgrade was well justified, and the reason for the demand for treasuries is that they look good compared to the other options right now.
  • There is a panic going on as investors adjust to lower growth expectations, due to lack of leadership in the US and Europe.
  • This is not a classical recession, rather a “Great Contraction”: Recessions are periodic, but a financial crisis like this is unusual, this is the 2nd Great Contraction since the Depresssion. It’s not output and employment, but credit and housing which are contracting, due to the “debt overhang”.
  • If you look at a contraction, it can take up to 4 or 5 years just to get back where you started.
  • This is not a double dip recession, because we never left the first one.
  • Rogoff thinks continued fiscal stimulus would worsen the debt overhang because it leads to the expectation of future tax increases, thus causing firms and households increased uncertainty and reduces future growth.
  • If we used our credit to help facilitate a plan to bring down the mortgage debt (debt held by the private sector), Rogoff would consider that a better option than spending on employment and output. Fix the debt problem, and spending will resume.
  • Rogoff thinks we should not assume that interest rates of US debt will last indefinitely. Infrastructure spending, if well spent, is great, but he is suspicious whether the government is able to target its spending so efficiently to make borrowing the money worthwhile.
  • Rogoff thinks if government invests in productive projects, stimulus is a good idea, but “digging ditches” will not fix the economy.
  • Until we get the debt levels down, we cannot get back to robust growth.
  • It’s because of the government’s debt that the private sector is worried about where the country’s going. If we increase the debt to finance more stimulus, there will be more uncertainty, higher interest rates, possibly inflation, and prolonged stagnation in output and incomes.
  • When it comes down to it, there is just too much debt in the economy!

Discussion Question:

  1. What is the fundamental difference between the two arguments being debated above? Both agree that the national debt is a problem, but where do the two economists differ on how to deal with the debt?
  2. The issues of “digging ditches and filling them in” comes up in the discussion. What is the context of this metaphor? What are the two economists views on the effectiveness of such projects?
  3. Following the debate, Fareed Zakaria talks about the reaction in China to S&P’s downgrade of US debt. What does he think about the popular demands in China for the government to pull out of the market for US government bonds?
  4. Explain what Zakaria means when he describes the relationship between the US and China as “Mutually Assured Destruction (MAD)”.
  5. Should the US government pursue a second stimulus and directly try to stimulate employment and income? Or should it continue down the path to austerity, cutting government programs to try and balance its budget?

20 responses so far

Apr 08 2011

The battle of ideas: Hayek versus Keynes on Aggregate Supply

Introduction: The two models below represent two very different views of a nation’s aggregate supply curve. The theories behind the two models represent the ideas about the macroeconomy of two economists, John Maynard Keynes and Friedrich von Hayek.

Instructions: The videos introducing Keynes’ and Hayek’s theories can be found here: “Commanding Heights: the Battle for Ideas”. We will watch them in class, but if you need to review them you may watch them again from home. Once you’ve watched the videos and read chapter 17 from your Course Companion, answer the questions that follow each of the two models below.
Figure 1: the Classical AD/AS model

  1. Why does Hayek’s “classical” aggregate supply curve always lead to an equilibrium level of national output equal to the full-employment level of

    real GDP?

  2. The vertical AS curve above is sometimes referred to as the “flexible-wage and flexible-price” model of the macroeconomy. Why must wages and prices be perfectly flexible for this model to be an accurate representation of a nation’s economy.
  3. Hayek was an advocate for free markets, he felt that government intervention in a nation’s economy would only interfere and disrupt the efficient allocation of resources. How does the model above reflect his belief that governments cannot improve a nation’s level of output beyond what the free market is able to achieve?
  4. Do you believe that the classical model of aggregate supply is representative of the real world? Why or why not? What evidence is there from recent history that the model is or is not accurate?

Figure 2: The Keynesian AD/AS model

  1. Based on the model above, which level of aggregate demand corresponds with the macroeconomic goals of “full-employment and stable


  2. Changes in which factors could cause aggregate demand to shift from AD2 to AD3? If AD falls to AD3, what happens to the price level in the economy? What happens to the level of output of goods and services? What happens to employment and unemployment?
  3. Sometimes the Keynesian AS model is known as the “sticky-wage and sticky-price model”. How does the model reflect the idea that wages are downwardly inflexible, in other words, will not fall even if demand for goods and services fall? For what reasons might wages in an economy be downwardly inflexible (in other words, not fall even as total demand in the economy falls)?
  4. How realistic is the Keynsian model of aggregate supply in the real world?
    1. Can you point to any evidence from the last few years that it might be correct (in other words, that a fall in AD will lead to decrease in national output?) Find data on the GDP’s of two Western European countries from 2008 and 2009 to support your findings.
    2. Can you point to any evidence from the last few years that the model might be flawed (in other words, that a fall in AD actually does lead to a fall in the price level)? Find data on inflation in the same two Western European countries to examine whether or not wages and prices are completely inflexible downwards as the model suggests.


Figure 3: Our IB Economics AD/AS model

The diagram above represents a compromise between the classical AD/AS model and the Keynesian AD/AS model. This graph is the one we will use throughout the IB and AP Economics course when illustrating a nation’s macroeconomy. Answer the questions that follow about the diagram.
  1. How does the above model represent a compromise between Keynes’ and Hayek’s view of aggregate supply?
  2. Why are there two aggregate supply curves? What is the difference between the two?
  3. What happens in the SHORT-RUN when AD falls from AD2 to AD3 to the price level and output? What will happen in the long-run? In macroeconomics, the short-run is known as the “fixed-wage period” and the long-run the “flexible-wage period”. The main factor that can shift the SRAS curve is the level of wages in the economy (in other words, a change in wages will shift the SRAS). How does this help explain the adjustment from the short-run equilibrium and the long-run equilibrium following a fall in AD?
  4. What happens in the SHORT-RUN when AD increases from AD2 to AD1? What will happen in the long-run? How does the long-run flexibility of wages explain why output always seems to return to its full employment level of output in the long-run?
  5. What does the model above indicate about the possible need for government intervention to help an economy achieve its macroeconomic goals of full-employment and price level stability in the short-run?

260 responses so far

Sep 17 2010

Supply – side economists: “lower taxes, more growth, more tax revenue!”

This is a follow up to a recent post to this blog, Hey, what are you Laffing at? The relationship between tax rate and tax revenue

The unbearable lightness of being Martin Feldstein | Free exchange |

Supply-side economics, advocated by most Republican politicians, including presidential candidate John McCain, places great emphasis on the idea that investment is the main engine of economic growth, price level stability, and low unemployment. To encourage firms to invest, government should play a minimal role in the economy; taxes should be sufficiently low to incentivize firms to invest, while at the same time government spending should be reduced to avoid crowding-out of private investment.

Without a healthy level of investment, a country’s capital stock wears out and is not replaced, raising costs of production and shifting short-run (and maybe even long-run) aggregate supply leftward. If investment remains sufficiently low, over time an economy’s output could even begin to shrink.

In the article below, The Economist’s Free Exchange explores the relationship between tax rates and long-run economic growth. The Economist takes the position of “supply-siders” who study the impact of tax rates on the level of output. The idea of supply-side economics is that lower taxes encourage more investment and thus higher growth rates.

Here’s the gist of the supply-side argument:

Our baseline specification suggests that an exogenous tax increase of one percent of GDP lowers real GDP by roughly three percent.

On the other hand…

…we find that a tax cut of one percent of GDP increases real output by approximately three percent over the next three years.

In the case of the Laffer Curve, which shows the relationship between tax rates and tax revenue, the article concludes that:

Tax cuts don’t exactly “pay for themselves”, but they also don’t diminish revenue after about two years. That is, after about two years, the government receives revenues equal to what it would have received at the higher rate, but taxpayers enjoy a lower burden. It is an important advance to discover that because cuts do lead to an immediate dip in revenue, they often inspire offsetting tax increases that retard the growth effect of the origina cut. Nevertheless, the effect of cuts on output is generally strong enough to bring revenue back to where it would have been otherwise.

Supply-side economics, folks. Understanding the effects of fiscal and monetary policies on not only aggregate demand, but on aggregate supply (both short-run and long-run) is a crucial skill in  answering AP free response questions.

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19 responses so far

Aug 28 2010

“Why can’t the government just print more money?” – NOT such a silly question!

I received the following email today, which gave me a great excuse to write a blog post about monetary policy! My reply to the teacher is below.


I hate to bug you, but I have a question. I am a first year AP Econ teacher and I know something is going to come up right away and I want to explain it in the simplest way. “Why can’t the govt. just print more money?” I know the inflation part of it, but when I am reading to look for quality ways of explaining it, I see plenty of information about it, but I can’t grasp it. Principle 9 in Mankiw text states “Prices rise when the govt. prints too much money.” I feel like a dumb kid and I am supposed to teach this!!!!

If you can help, great, if not, I will figure it out.


Dear Teacher,

I love your question! It is definitely one of those issues that gets glossed over in most economics textbooks. Or it is assumed that the money supply diagram makes it obvious why excessive monetary growth leads to inflation. But I agree, this is one of those things that for the first couple of years I taught economics, I probably didn’t really understand all that well either! So let me try to break it down in plain English for you. This will be good for me too, cause I always understand things more clearly myself after writing them (which is why writing a textbook is about the best PD I’ve every undertaken!)

So, here it goes:

Printing money and its effect on inflation is a bit more complicated than it sounds. In fact, it is the US treasury that prints money, but it is the Federal Reserve that determines how much money is actually in circulation in the economy. Money printed by the Treasury is distributed to the twelve Federal Reserve banks around the country. The treasury and the government of which it is a part does not have any say on how much money actually gets injected into the economy, as monetary policy decisions are left up to the Federal Reserve.

Traditionally, the Fed has one tool for injecting new money into the economy, a tool known as “open market operations”. (I say traditionally, because in the last three years the Fed has devised numerous new ways to “inject liquidity” into the economy, which I will not get into now). To increase the nation’s money supply, the Fed buys US government bonds on the open market from commercial banks. Commercial banks invest some of American households’ savings into government bonds just like they invest some of our money into individuals and businesses by making loans and charging interest on those loans. Commercial banks will want to buy government bonds if the interest on them rises and will want to sell those bonds when the interest rate falls.

If the Fed want to increase the money supply to stimulate spending in the economy, it will announce an open market purchase of bonds. When the Fed buys bonds, the demand for bonds increases, raising their prices and lowering their effective interest rate. As the interest on government bonds falls as a result of the Fed’s open market operations, banks find them less desirable to hold onto as investments and therefore sell them to the Fed in exchange for, you guessed it, liquid money, fresh off the printing presses!

Remember, the money printed at the Treasury and held at the Fed was NOT part of the money supply, since it is out of reach of private borrowers. But as soon as the Fed buys bonds with that money, it is deposited into commercial banks’ excess reserves and is therefore now in the commercial banking system and therefore part of the money supply. So, “printing money” does not immediately increase the money supply since newly printed money only ends up in the Fed; only once the Fed has undertaken an expansionary monetary policy (an open market bond purchase) does the newly printed money enter the money supply.

Now, commercial banks have just sold their illiquid assets (government bonds) to the Fed in exchange for liquid money. Picture the money market diagram and you will see the money supply increasing.

So the next question is, why does this lead to inflation?

Banks now hold more excess reserves, most of which are kept on reserve at their regional Federal Reserve bank. Reserves held at the Fed do NOT earn interest for the banks, and therefore actually lose value over time as inflation erodes the purchasing power of these idle reserves. Banks, of course, want to invest these reserves to earn interest beyond the rate of inflation and thereby create earn them revenue. In order to attract new borrowers, commercial banks, whose reserves have increased following the Fed’s bond purchase, must offer borrowers a lower interest rate. The increase in the supply of money leads to a decrease in the “price” of money, i.e. the interest rates banks charge borrowers.

So here we see why an increase in the money supply leads to lower interest rates. With greater excess reserves, banks must lower the rate they charge each other (the federal funds rate) and thus the prime rate they charge their most credit-worthy borrowers and all other interest rates in the economy, in order to attract new borrowers and get their idle reserves out there earning interest for the bank.

Lower interest rates create an incentive for firms to invest in new capital since now more investment projects have an expected rate of return equal to or greater than the new lower interest rate. Additionally, the lower rates on savings discourages savings by households and thereby increases the level of household consumption. Households find it cheaper to borrow money to purchase durable goods like cars and it also becomes cheaper to buy new homes or undertake costly home improvements. So we begin to see investment and consumption rise across the economy as the increase in the money supply reduces borrowing costs and decreases the incentive to save. Aggregate demand has started to rise.

Additionally, the lower rate on US government bonds resulting from the Fed’s open market purchase reduces the incentive for foreign investors to save their money in US bonds and in US banks, which are now offering lower interest rates. Falling foreign demand for the dollar causes it to depreciate. A weaker dollar makes US exports more attractive to foreign consumers, so in addition to increased consumption and investment in the US, net exports begin to rise as well, further increasing aggregate demand.

Increasing the money supply (not so much by printing money rather because of the “easy money” policy of the Fed), leads to increased consumption, investment, and net exports, and therefore aggregate demand in the economy. The rising demand among domestic consumers, foreign consumers, and domestic producers for the nation’s output puts upward pressure on prices as the nation’s producers find it hard to keep up with the rising demand. Once consumers start to see prices rising, inflationary expectations will further increase the incentive to buy more now and save less, leading to even more household consumption. Firms see price rises in the future and increase their investment now to meet the expected rises in demand tomorrow.

It does not take much for inflation to accelerate in such an environment. If the the government and the Fed do not slow down the increase in the money supply (STOP THE PRINTING PRESSES!) then soon enough workers will begin demanding higher wages and resource costs will start to increase in all sectors of the economy, causing the nation’s aggregate supply to decline as firms find it harder to cover their rising costs. Now we have both demand-pull AND cost push inflation! The weaker currency also makes imported raw materials more costly to firms, further adding to the inflationary environment. An inflationary spiral is now underway!

Milton Friedman said that “inflation is always and everywhere a monetary phenomenon”. Controlling the rate of growth in the money supply, say the monetarists, will assure that the fluctuations in the business cycle will be mild and periods of dramatic inflation and deflation can be avoided. Stable money growth should lead to stable economic growth. But as soon as we start running the printing presses inflation will not be far behind. On the flip-side, contractionary monetary policies should in theory lead to the exact opposite of what I describe above and cause a deflation. If a central bank were to tighten the money supply too much, interest rates would rise, investment, consumption and net exports would fall, and falling prices would force firms to lay off workers, leading to high unemployment and an economic contraction.

I’ll leave you with one question to ponder (the answer to which would require a much longer article than this one!). If Friedman was right, and increasing the money supply will always and everywhere lead to inflation, then how is it that the monetary base in the United States increased by 142% between 2008 and 2009, yet inflation declined over the same period and fell to as low as -2% in mid-2009? That’s right, the money supply more than doubled, yet the economy went into deflation. Was Friedman missing something in his calculation that monetary growth always leads to price level increases? In other words, is an open market purchase of bonds by the Fed all that is needed to stimulate demand during a recession? Perhaps Friedman, who died in 2006 right before the US entered the Great Recession, would have to re-consider his famous quote if he could see the effect (or lack of effect) of America’s unprecedented monetary growth over the last three years!

57 responses so far

Jan 28 2010

The best Econ rap… EVER!! – A new resource for Econ teachers and students, from Russ Roberts and John Papola

The long awaited rap video from George Mason University’s Russ Roberts featuring the theories of John Maynard Keynes and F. A. Hayek has been released at last!

We’ve heard some decent Econ raps before (remember “Demand, Supply” by Rhythm, Rhyme, Results?) But this song covers all bases in the predominant macroeconomic schools of thought. Keynes and Hayek are brought back to life and their theories pitted against one another in an all out liquor fueled debate on the streets of New York City.

The video was just released this week. It is packed full of theory from the Classical, supply-side school of macroeconomics (represented by Hayek) and the demand-side school (represented, of course, by Keynes). The video includes cameos from Fed chairman Ben Bernanke and Treasury Secretary Tim Geithner, whose role as bartenders filling Keynes glass reflects their role in the real economy at keeping the money supply and government spending at high levels, fueling economic booms and the eventual busts that result.

Stay tuned to this blog for more feedback on the video, including some graphical analysis and discussion questions for Macro teachers to use in class!

2 responses so far

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