LONDON — This is a tough time to be a decision-maker. We live in an era of low predictability. The world appears in constant flux. The challenges are immense. And most of all, there is in many instances a clash between the correct short-term politics and the correct long-term policy.

On the economy, the climate debate and security, the immediate pressures pretty much run one way: increase the role of government in the economy; put the climate deal off to more congenial financial times; and get out of substantial military commitment to fighting global terrorism. Yet in each case the right long-term policy almost certainly points to the opposite course.

What is the way to bridge this gap between short and long term? To decide how to do that is to decide fundamentally what we believe in and what we want from our future. In deciding this, only the head can guide us in how to do it; but the heart must tell us what it is we truly believe in doing.