“For more than a generation Western governments have been borrowing on a large scale from their own citizens but increasingly also from foreigners in much poorer countries. The cost of these promises will be piled onto taxpayers as yet unborn or too young to vote.”

At the moment, we appear to be leaving future generations a rather bad hand. Public debt seems to verge on the unsustainable, and the number of things they’ll to pay for, whether cleaning the environment or reducing inequality, seem to be increasing. Axel Weber, previously president of Germany’s Bundesbank, once joked that in face of spiraling debt, future generations “are doing the only thing they can. They’re avoiding being born.” One of the less common explanations for Europe’s demographic crisis.

A fairly basic law says that what cannot go on forever will stop. Whether it is climate change, public borrowing, inequality, or deteriorating social capital, says Coyle, we’re in the midst of a number of unsustainable trends, ones that can and must change. That means measuring things properly (as she discusses in depth in another book, GDP: A Short History), and making decisions as if the future matters, indeed as if we should leave the next generation with at least as much capital as we inherited.

In the end, Coyle is hopeful: by curbing our instinct to demand ever more, and making sure we think about the consequences for the future of our decisions today, she says, we can do a lot to leave future generations in a good position. This also means facing basic trade-offs, though, instead of pretending they don’t exist and borrowing to avoid them: she suggests, for example, that we should pick any two of efficiency, fairness, and freedom, but that not all three can be achieved simultaneously.

It’s not a new message, perhaps, but it is an important message. We could do a lot more to care for future generations (some days, it might be fair doing anything would be an improvement, Elon Musk excepted). Coyne mixes some practical suggestions with philosophical discussion, and if it doesn’t quite feel like she’s cracked the problem, she’s at least thinking about the right things.