Sir Boyle Roche was an Irish parliamentarian of the 18th century who achieved a reputation for remarks stupid even by the standards of politicians. “How could I be in two places at once unless I were a bird?” was his excuse for an absence that few of his contemporaries regretted. But another observation — “Why we should put ourselves out of our way to do anything for posterity, for what has posterity ever done for us?” — is the one he bequeathed to, well, posterity.
Public debt, which in Britain is fast approaching 100 per cent of national income, is the method by which we snub posterity today. If we run a deficit of 5 per cent of gross domestic product, we enrich ourselves by 5 per cent at the expense of future generations — at least, relative to how we would have done if we had not run a deficit and everything else had remained the same. I have phrased that sentence carefully to illustrate how many assumptions are needed to interpret the effects of such a policy. There are many concepts of deficit (which more intelligent politicians than Roche readily confuse), inflation is eroding the real value of outstanding debt, and it is unlikely (indeed impossible) that everything else would have remained the same. Still, those of us who do care for posterity cannot but be concerned by our legacy of debt.
But public debt is not the only, or necessarily the most important, means by which we make transfers between generations. If public debt is the liability of posterity, public infrastructure is the asset of posterity. A glance around London leaves one impressed by and grateful for the legacy of our Victorian forebears — the embankments, the rail links into the city, the tube tunnels beneath it, the Houses of Parliament. By comparison, Crossrail, the Millennium bridge, the Shard and the lowest rate of new housebuilding for decades are our rather meagre contributions today.