Ninety years ago, in his A Tract on Monetary Reform Keynes famously wrote “In the long run we are all dead”. That observation recently stirred a lot of debate for all the wrong reasons, after Niall Ferguson obnoxiously claimed that Keynes did not care about the future because he was childless. Whether Keynes cared about the long-term future or not (and whether he had children or not) is completely irrelevant in this context, as many (e.g. Brad DeLong and Paul Krugman) have pointed out.
The actual context in which Keynes wrote this observation was a discussion about the quantity theory of money, which states that doubling the supply of money will only double the prices, but will have no consequences for other parts of the economy. This is the classical dichotomy between real and nominal variables. Keynes argued: “Now in the long run this is probably true”. But “In the long run we are all dead. Economists set themselves too easy, too useless a task if in tempestuous seasons they can only tell us that when the storm is long past the ocean is flat again.” So, Keynes’ point was obviously not that the future doesn’t matter. His point was that simple theories that might describe long-term relationships are just not good enough to deal with current issues. In the short run, changes in money supply can have all kinds of important consequences beyond the price levels. Economists will have to make their hands dirty and delve into the complicated dynamics of the here and now.