Impossible trinity

Last updated February 23, 2024

The impossible trinity (also known as the impossible trilemma, the monetary trilemma or the Unholy Trinity) is a concept in international economics and international political economy which states that it is impossible to have all three of the following at the same time:

It is both a hypothesis based on the uncovered interest rate parity condition, and a finding from empirical studies where governments that have tried to simultaneously pursue all three goals have failed. The concept was developed independently by both John Marcus Fleming in 1962 and Robert Alexander Mundell in different articles between 1960 and 1963.^[1]

Historically in advanced economies, the periods pre-1914 and 1970–2014 were characterized by stable foreign exchange rates and free capital movement, whereas monetary autonomy was limited. The periods 1914–1924 and 1950–1969 had restrictions on capital movement (e.g. capital controls), but exchange rate stability and monetary autonomy were present.^[2]^[3]

Policy choices

According to the impossible trinity, a central bank can only pursue two of the above-mentioned three policies simultaneously. To see why, consider this example (which abstracts from risk but this is not essential to the basic point):

Assume that world interest rate is at 5%. If the home central bank tries to set domestic interest rate at a rate lower than 5%, for example at 2%, there will be a depreciation pressure on the home currency, because investors would want to sell their low yielding domestic currency and buy higher yielding foreign currency. If the central bank also wants to have free capital flows, the only way the central bank could prevent depreciation of the home currency is to sell its foreign currency reserves. Since foreign currency reserves of a central bank are limited, once the reserves are depleted, the domestic currency will depreciate.

Hence, all three of the policy objectives mentioned above cannot be pursued simultaneously. A central bank has to forgo one of the three objectives. Therefore, a central bank has three policy combination options.

Options

In terms of the diagram above (Oxelheim, 1990), the options are:

Option (a): A stable exchange rate and free capital flows (but not an independent monetary policy because setting a domestic interest rate that is different from the world interest rate would undermine a stable exchange rate due to appreciation or depreciation pressure on the domestic currency).
Option (b): An independent monetary policy and free capital flows (but not a stable exchange rate).
Option (c): A stable exchange rate and independent monetary policy (but no free capital flows, which would require the use of capital controls).

Currently, Eurozone members have chosen the first option (a) after the introduction of the euro. By contrast, Harvard economist Dani Rodrik advocates the use of the third option (c) in his book The Globalization Paradox , emphasising that world GDP grew fastest during the Bretton Woods era when capital controls were accepted in mainstream economics. Rodrik also argues that the expansion of financial globalization and the free movement of capital flows are the reason why economic crises have become more frequent in both developing and advanced economies alike. Rodrik has also developed the political trilemma of the world economy where "democracy, national sovereignty and global economic integration are mutually incompatible: we can combine any two of the three, but never have all three simultaneously and in full."^[4]

Theoretical derivation

The formal model underlying the hypothesis is the uncovered Interest Rate Parity condition which states that in absence of a risk premium, arbitrage will ensure that the depreciation or appreciation of a country's currency vis-à-vis another will be equal to the nominal interest rate differential between them. Since under a peg, i.e. a fixed exchange rate, short of devaluation or abandonment of the fixed rate, the model implies that the two countries' nominal interest rates will be equalized. An example of which was the consequential devaluation of the peso,^{[ which? ]} that was pegged to the US dollar at 0.08, eventually depreciating by 46%. ^{[ citation needed ]} This in turn implies that the country implementing the peg has no ability to set its nominal interest rate independently, and hence no independent monetary policy. The only way then that the country could have both a fixed exchange rate and an independent monetary policy is if it can prevent arbitrage in the foreign exchange rate market from taking place – by instituting capital controls on international transactions.

Trilemma in practice

The idea of the impossible trinity went from theoretical curiosity to becoming the foundation of open economy macroeconomics in the 1980s, by which time capital controls had broken down in many countries, and conflicts were visible between pegged exchange rates and monetary policy autonomy. While one version of the impossible trinity is focused on the extreme case – with a perfectly fixed exchange rate and a perfectly open capital account, a country has absolutely no autonomous monetary policy – the real world has thrown up repeated examples where the capital controls are loosened, resulting in greater exchange rate rigidity and less monetary-policy autonomy.

In 1997, Maurice Obstfeld and Alan M. Taylor brought the term "trilemma" into widespread use within economics.^[5] In work with Jay Shambaugh, they developed the first methods to empirically validate this central, yet hitherto untested, hypothesis in international macroeconomics.^[6]

Economists Michael C. Burda and Charles Wyplosz provide an illustration of what can happen if a nation tries to pursue all three goals at once. To start with they posit a nation with a fixed exchange rate at equilibrium with respect to capital flows as its monetary policy is aligned with the international market. However, the nation then adopts an expansionary monetary policy in order to try to stimulate its domestic economy.

This involves an increase of the monetary supply, and a fall of the domestically available interest rate. Because the internationally available interest rate adjusted for foreign exchange differences has not changed, market participants are able to make a profit by borrowing in the country's currency and then lending abroad – a form of carry trade.

With no capital control, market players will do this en masse. The trade will involve selling the borrowed currency on the foreign exchange market in order to acquire foreign currency to invest abroad – and this tends to cause the price of the nation's currency to drop due to the sudden extra supply. Because the nation has a fixed exchange rate, it must defend its currency and will sell its reserves in order to buy its currency back. However, unless the monetary policy is changed back, the international markets will invariably continue until the government's foreign exchange reserves are exhausted,^{[note 1]} thereby causing the currency to devalue, thus breaking one of the three goals and also enriching market players at the expense of the government that tried to break the impossible trinity.^[7]

A 2022 study of the Classical Gold Standard period found that the behavior of advanced economies to international shocks was consistent with the impossible trilemma.^[8]

Possibility of a dilemma

In the modern world, given the growth of trade in goods and services and the fast pace of financial innovation, it is possible that capital controls can often be evaded. In addition, capital controls introduce numerous distortions. Hence, there are few important countries with an effective system of capital controls, though by early 2010, there has been a movement among economists, policy makers and the International Monetary Fund back in favour of limited use.^[9]^[10]^[11] Lacking effective control on the free movement of capital, the impossible trinity asserts that a country has to choose between reducing currency volatility and running a stabilising monetary policy: it cannot do both. As stated by Paul Krugman in 1999:^[12]

The point is that you can't have it all: A country must pick two out of three. It can fix its exchange rate without emasculating its central bank, but only by maintaining controls on capital flows (like China today); it can leave capital movement free but retain monetary autonomy, but only by letting the exchange rate fluctuate (like Britain – or Canada); or it can choose to leave capital free and stabilize the currency, but only by abandoning any ability to adjust interest rates to fight inflation or recession (like Argentina today,^{[note 2]} or for that matter most of Europe).

Historical events

The combination of the three policies – fixed exchange rate, free capital flow, and independent monetary policy – is known to cause financial crisis. The Mexican peso crisis (1994–1995), the 1997 Asian financial crisis (1997–1998), and the Argentinean financial collapse (2001–2002)^[13] are often cited as examples.

In particular, the East Asian crisis (1997–1998) is widely known as a large-scale financial crisis caused by the combination of the three policies which violate the impossible trinity.^[14] The East Asian countries were taking a de facto dollar peg (fixed exchange rate),^[15] promoting the free movement of capital (free capital flow)^[14] and making independent monetary policy at the same time. First, because of the de facto dollar peg, foreign investors could invest in Asian countries without the risk of exchange rate fluctuation. Second, the free flow of capital kept foreign investment uninhibited. Third, the short-term interest rates of Asian countries were higher than the short-term interest rate of the United States from 1990 to 1999. For these reasons, many foreign investors invested enormous amounts of money in Asian countries and reaped huge profits. While the Asian countries' trade balance was favorable, the investment was pro-cyclical for the countries. But when the Asian countries' trade balance shifted, investors quickly retrieved their money, triggering the Asian crisis. Eventually countries such as Thailand ran out of dollar reserves and were forced to let their currencies float and devalue. Since many short-term debt obligations were denoted in US dollars, debts grew substantially and many businesses had to shut down and declare bankruptcy. The disorderly collapse of fixed exchange rate regimes in Asia was anticipated in Obstfeld and Rogoff, who showed that empirically almost no fixed exchange rate regime had survived five years once the capital account was opened.^[16]

Notes

↑ In real-life examples, as the market players reach the point where they suspect the government is running out of the reserves to defend its currency, they will pile in with direct speculative attacks where they borrow and sell the nation's currency without bothering with carry trades, leading to a quick profit once the inevitable devaluation occurs.
↑ Note that this was written in 1999, when Argentina had a Fixed exchange rate. Argentina abandoned this in January 2002. See Argentine economic crisis (1999–2002)

Related Research Articles

In finance, an exchange rate is the rate at which one currency will be exchanged for another currency. Currencies are most commonly national currencies, but may be sub-national as in the case of Hong Kong or supra-national as in the case of the euro.

The global financial system is the worldwide framework of legal agreements, institutions, and both formal and informal economic action that together facilitate international flows of financial capital for purposes of investment and trade financing. Since emerging in the late 19th century during the first modern wave of economic globalization, its evolution is marked by the establishment of central banks, multilateral treaties, and intergovernmental organizations aimed at improving the transparency, regulation, and effectiveness of international markets. In the late 1800s, world migration and communication technology facilitated unprecedented growth in international trade and investment. At the onset of World War I, trade contracted as foreign exchange markets became paralyzed by money market illiquidity. Countries sought to defend against external shocks with protectionist policies and trade virtually halted by 1933, worsening the effects of the global Great Depression until a series of reciprocal trade agreements slowly reduced tariffs worldwide. Efforts to revamp the international monetary system after World War II improved exchange rate stability, fostering record growth in global finance.

<span class="mw-page-title-main">1997 Asian financial crisis</span> Financial crisis of many Asian countries during the second half of 1997

The 1997 Asian financial crisis was a period of financial crisis that gripped much of East and Southeast Asia during the late 1990s. The crisis began in Thailand in July 1997 before spreading to several other countries with a ripple effect, raising fears of a worldwide economic meltdown due to financial contagion. However, the recovery in 1998–1999 was rapid, and worries of a meltdown quickly subsided.

<span class="mw-page-title-main">Monetary policy</span> Policy of interest rates or money supply

Monetary policy is the policy adopted by the monetary authority of a nation to affect monetary and other financial conditions to accomplish broader objectives like high employment and price stability. Further purposes of a monetary policy may be to contribute to economic stability or to maintain predictable exchange rates with other currencies. Today most central banks in developed countries conduct their monetary policy within an inflation targeting framework, whereas the monetary policies of most developing countries' central banks target some kind of a fixed exchange rate system. A third monetary policy strategy, targeting the money supply, was widely followed during the 1980s, but has diminished in popularity since that, though it is still the official strategy in a number of emerging economies.

In economics, hot money is the flow of funds from one country to another in order to earn a short-term profit on interest rate differences and/or anticipated exchange rate shifts. These speculative capital flows are called "hot money" because they can move very quickly in and out of markets, potentially leading to market instability.

In macroeconomics and modern monetary policy, a devaluation is an official lowering of the value of a country's currency within a fixed exchange-rate system, in which a monetary authority formally sets a lower exchange rate of the national currency in relation to a foreign reference currency or currency basket. The opposite of devaluation, a change in the exchange rate making the domestic currency more expensive, is called a revaluation. A monetary authority maintains a fixed value of its currency by being ready to buy or sell foreign currency with the domestic currency at a stated rate; a devaluation is an indication that the monetary authority will buy and sell foreign currency at a lower rate.

The Mexican peso crisis was a currency crisis sparked by the Mexican government's sudden devaluation of the peso against the U.S. dollar in December 1994, which became one of the first international financial crises ignited by capital flight.

Foreign exchange reserves are cash and other reserve assets such as gold held by a central bank or other monetary authority that are primarily available to balance payments of the country, influence the foreign exchange rate of its currency, and to maintain confidence in financial markets. Reserves are held in one or more reserve currencies, nowadays mostly the United States dollar and to a lesser extent the euro.

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In macroeconomics and economic policy, a floating exchange rate is a type of exchange rate regime in which a currency's value is allowed to fluctuate in response to foreign exchange market events. A currency that uses a floating exchange rate is known as a floating currency, in contrast to a fixed currency, the value of which is instead specified in terms of material goods, another currency, or a set of currencies.

In macroeconomics and international finance, the capital account, also known as the capital and financial account, records the net flow of investment into an economy. It is one of the two primary components of the balance of payments, the other being the current account. Whereas the current account reflects a nation's net income, the capital account reflects net change in ownership of national assets.

A currency crisis is a type of financial crisis, and is often associated with a real economic crisis. A currency crisis raises the probability of a banking crisis or a default crisis. During a currency crisis the value of foreign denominated debt will rise drastically relative to the declining value of the home currency. Generally doubt exists as to whether a country's central bank has sufficient foreign exchange reserves to maintain the country's fixed exchange rate, if it has any.

The Mundell–Fleming model, also known as the IS-LM-BoP model, is an economic model first set forth (independently) by Robert Mundell and Marcus Fleming. The model is an extension of the IS–LM model. Whereas the traditional IS-LM model deals with economy under autarky, the Mundell–Fleming model describes a small open economy.

Capital controls are residency-based measures such as transaction taxes, other limits, or outright prohibitions that a nation's government can use to regulate flows from capital markets into and out of the country's capital account. These measures may be economy-wide, sector-specific, or industry specific. They may apply to all flows, or may differentiate by type or duration of the flow.

Currency intervention, also known as foreign exchange market intervention or currency manipulation, is a monetary policy operation. It occurs when a government or central bank buys or sells foreign currency in exchange for its own domestic currency, generally with the intention of influencing the exchange rate and trade policy.

A fixed exchange rate, often called a pegged exchange rate, is a type of exchange rate regime in which a currency's value is fixed or pegged by a monetary authority against the value of another currency, a basket of other currencies, or another measure of value, such as gold.

In macroeconomics, sterilization is action taken by a country's central bank to counter the effects on the money supply caused by a balance of payments surplus or deficit. This can involve open market operations undertaken by the central bank whose aim is to neutralize the impact of associated foreign exchange operations. The opposite is unsterilized intervention, where monetary authorities have not insulated their country's domestic money supply and internal balance against foreign exchange intervention.

Self-fulfilling crisis refers to a situation that a financial crisis is not directly caused by the unhealthy economic fundamental conditions or improper government policies, but a consequence of pessimistic expectations of investors. In other words, investors' fear of the crisis makes the crisis inevitable, which justified their initial expectations.

Fear of floating refers to situations where a country prefers a fixed exchange rate to a floating exchange rate regime. This is more relevant in emerging economies, especially when they suffered from financial crisis in the last two decades. In foreign exchange markets of the emerging market economies, there is evidence showing that countries who claim they are floating their currency, are actually reluctant to let the nominal exchange rate fluctuate in response to macroeconomic shocks. In the literature, this is first convincingly documented by Calvo and Reinhart with "fear of floating" as the title of one of their papers in 2000. Since then, this widespread phenomenon of reluctance to adjust exchange rates in emerging markets is usually called "fear of floating". Most of the studies on "fear of floating" are closely related to literature on costs and benefits of different exchange rate regimes.

References

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↑ Obstfeld, Maurice; Taylor, Alan M. (1998). "The Great Depression as a Watershed: International Capital Mobility in the Long Run". In Bordo, Michael D.; Goldin, Claudia; White, Eugene N. (eds.). The Defining Moment: The Great Depression and the American Economy in the Twentieth Century. Chicago: University of Chicago Press. pp. 353–402. doi:10.3386/w5960. ISBN 978-0-226-06589-2. S2CID 152881930.
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↑ Bazot, Guillaume; Monnet, Eric; Morys, Matthias (2022). "Taming the Global Financial Cycle: Central Banks as Shock Absorbers in the First Era of Globalization". The Journal of Economic History. 82 (3): 801–839. doi:10.1017/S0022050722000274. ISSN 0022-0507. S2CID 251268787.
↑ Dani Rodrik (2010-03-11). "The End of an Era in Finance". Project Syndicate . Retrieved 2010-05-24.
↑ Kevin Gallagher (2010-03-01). "Capital controls back in IMF toolkit". The Guardian . Retrieved 2010-05-24.
↑ Subramanian, Arvind (2009-11-18). "Time For Coordinated Capital Account Controls?". The Baseline Scenario. Retrieved 2009-12-15.
↑ Paul Krugman (1999-10-10). "O Canada – a neglected nation gets its Nobel". Slate . Retrieved 2010-06-01.
↑ Aizenman, Joshua (2010), The Impossible Trinity (aka The Policy Trilemma), University of California, Santa Cruz: Department of Economics, p. 11
1 2 Patnaik, Ila; Shah, Ajay (2010), "Asia confronts the impossible trinity" (PDF), Working Paper 2010-64, New Delhi: National Institute of Public Finance and Policy, archived from the original (PDF) on 2017-09-22, retrieved 2014-08-06
↑ Garnaut, R. (1999). Southeast Asia's Economic Crisis: Origins, Lessons, and the Way Forward. Heinz Wolfgang Arndt and Hal Hill, Institute of Southeast Asian Studies. ISBN 9789813055896.
↑ Obstfeld, Maurice; Rogoff, Kenneth (December 1995). "The Mirage of Fixed Exchange Rates". Journal of Economic Perspectives. 9 (4): 73–96. doi: 10.1257/jep.9.4.73 . ISSN 0895-3309.