Take the simple example of a precipitous decline in oil prices. In the case of Trinidad and Tobago, this could lead to a decline in growth and employment and perhaps call for a lowering of interest rates to boost domestic demand.
We could have acted differently and reduced the interest rate drastically to bring inflation back within the target much more quickly, but then we could have created an unstable process of overshooting in the opposite direction, with inflation exceeding the target.