However, in the euro area, all the available evidence so far points to the existence of a stable relationship between M3 and price developments over the medium term. M3 and other monetary and credit aggregates also demonstrate leading indicator properties for future price developments. In the end, it is this evidence which makes us confident that monetary and credit aggregates are an important indicator for assessing risks to price stability. The second pillar of the strategy is associated with a complementary, but more eclectic, approach, which implies that a wide range of indicators is of relevance for monetary policy. While inflation is a 3  BIS Review 44/2000  monetary phenomenon over the medium term, at shorter horizons it will be influenced by many other variables. Changes in international commodity prices, such as the price of oil, will influence developments in consumer price inflation. Demand and cost pressures can also influence price developments in the shorter term. Moreover, policymakers will generally need to tailor their actions to the prevailing economic circumstances, since the impact of monetary policy on the future evolution of the price level at any specific time will depend on a host of factors which are not captured by monetary data. Analysis under the second pillar is intended to reveal this information, giving policymakers greater insight into shorter-run price dynamics and their implications for monetary policy. Monetary policymaking in the euro area has to reflect the complexities and uncertainties which surround the transmission mechanism of monetary policy in a wholly new economic entity.
These uncertainties imply that no single approach is likely to be entirely reliable. The inherent uncertainty faced by the central bank cannot simply be wished away. Reliance on a single indicator or forecast, or a single model of the economy or view of the world, would, in these circumstances, be extremely unwise. The strategy needs to incorporate the full range of relevant indicators and assess them in the context of a variety of different models. In this respect, the two pillars complement one another. They allow for a structured cross-checking of the evidence and analysis underlying policy decisions, encompass all information and allow for various views of the structure of the economy. The academic literature and other external commentators are slowly coming to recognise the importance of “robustness” in monetary policymaking - something which I believe has been understood by central bankers for some time. A successful monetary policy is not one that performs “optimally” in the context of a specific model or given a particular view of the world. In the light of our limited understanding of how the economy works, no single model is reliable enough. Rather given the great uncertainty faced by central banks - a successful monetary policy should perform well in a broad range of possible situations and across a variety of models or views of the world, each one of which may capture important aspects of actual economic behaviour or may, ex post, turn out to be close to reality. Monetary policymaking is therefore complex.