An important debate among economists in the second half of the twentieth century concerned the central bank's ability to predict how much money should be in circulation, given current employment rates and inflation rates. Economists such as Milton Friedman believed that the central bank would always get it wrong, leading to wider swings in the economy than if it were just left alone. This is why they advocated a non-interventionist approach—one of targeting a pre-specified path for the money supply independent of current economic conditions—even though in practice this might involve regular intervention with open market operations (or other monetary-policy tools) to keep the money supply on target.