Why Singapore Chooses Exchange-Rate Policy, and the Impact of a Fall in World Interest Rates

Answer

Part (a)

Internal stability refers to the achievement of Singapore’s domestic macroeconomic goals — price stability, low unemployment, and economic growth. Singapore’s choice of the exchange-rate-centred monetary policy as its main instrument follows from the structural nature of its economy and the limits the policy trilemma places on alternatives.

Import-reliant nature. With negligible natural resources, Singapore imports the bulk of its raw materials and essential goods, so a root cause of inflation is high imported cost of production. An appreciating exchange rate lowers the domestic-currency price of imported inputs, reducing firms’ unit costs and shifting SRAS rightward — directly targeting the source of cost-push inflation. Because the exchange rate acts on the actual root of price instability, it is the effective instrument for price stability.

Export-oriented nature. As a small, open economy, Singapore is export-led, so depressed net-export revenue is a root cause of slow growth. A depreciating exchange rate makes exports cheaper in foreign currency and imports dearer at home; provided the Marshall-Lerner condition holds, net exports rise, aggregate demand rises, and national income rises more than proportionately through the multiplier. The exchange rate thus operates on both of Singapore’s principal macroeconomic levers — costs and external demand.

The policy trilemma and Singapore as an interest-rate taker. Under the policy trilemma, an economy can have at most two of: free capital mobility, a managed exchange rate, and an independent interest rate. Singapore, a global financial centre, chooses free capital flows and exchange-rate control — and therefore forgoes interest-rate independence. Were the Monetary Authority to raise domestic interest rates above world rates, short-term capital would flood in to exploit the differential, raising internal liquidity and the money supply until interest rates fell back to the world level. Singapore is thus an interest-rate taker, so an independent interest-rate-based monetary policy is ineffective. The exchange rate is chosen as the main instrument precisely because the conventional monetary lever is closed off.

In sum, Singapore’s import-reliant, export-led structure makes the exchange rate the instrument that targets the true roots of its macroeconomic problems, while the trilemma and its interest-rate-taker status render domestic monetary policy ineffective.

Part (b)

A fall in world interest rates affects Singapore both externally, through its trading partners, and internally, because Singapore is an interest-rate taker so domestic rates fall too. My thesis is that the impact is positive on balance in the short run — supporting growth and the external balance — but carries inflationary and external risks in the longer run that qualify the verdict.

Positive: stronger external demand and improved balance of payments. Lower interest rates in Singapore’s major trading partners reduce their cost of borrowing, raising their consumption and investment and hence their AD and national income. Higher partner income raises demand for Singapore’s exports, raising export revenue $X$ and improving the current account and the overall balance of payments.

Positive: higher domestic AD, actual and potential growth. Because Singapore is an interest-rate taker, its domestic rates fall in step, raising domestic $C$ and $I$. Combined with the rise in $X$ — which is a large share of Singapore’s AD — aggregate demand rises significantly, lifting actual growth and lowering cyclical unemployment.

The higher investment also raises the capital stock, shifting LRAS rightward and supporting potential growth, so that growth can be sustained and non-inflationary.

Negative: demand-pull and imported inflation. If Singapore is already near full employment, the rise in AD generates demand-pull inflation. Trading partners, similarly stimulated, also face demand-pull inflation, raising global prices; since Singapore is import-reliant, this raises imported input costs and generates cost-push inflation at home.

Negative: hot-money inflows and an unwanted appreciation. With world rates lower, Singapore’s relatively higher short-term rates attract hot money. The inflow raises demand for the SGD, appreciating it (supply held constant). Given the Marshall-Lerner condition, the appreciation lowers net exports, dragging down AD and national income and raising cyclical unemployment — significant because $X$ is so large a share of Singapore’s AD.

Judgement. Whether the impact is positive depends on the state of the economy and on confidence. With substantial spare capacity, the demand-pull risk is small and the growth and external-balance gains dominate, so the impact is positive. Near full employment, the inflationary and appreciation risks bite, and the verdict weakens. Much also depends on whether Singapore’s existing policy mix — exchange-rate management to contain imported inflation and any appreciation pressure — can capture the benefits while offsetting the costs. On balance, with appropriate policy and given the present prevalence of spare capacity, a fall in world interest rates is more likely positive than negative for Singapore.