In the Asterix stories, Chief Vitalstatistix is afraid that the sky will fall on his head tomorrow. Fortunately for him, tomorrow never comes. But the reliable fact of tomorrow never coming is bad news when it comes to planning - and, in particular, to financial affairs. The Turner commission on pensions ranked the common inability to make "rational long-term savings decisions without encouragement" as the top barrier to better pensions provision. Turner drew on the growing field of behavioural economics to argue that people rank today's consumption irration ally highly, and so put off starting a pension until "tomorrow". This phenomenon is dubbed financial myopia, and it is the most important reason why the state has to intervene to encourage, or even compel, higher pensions savings.

Neuroscientists such as Colin Camerer and Brian Knutson have shown that when we make a decision relating to the immediate future, the "emotional" bits of our brain get fired up. When we make decisions with longer-term consequences, the "rational" parts are in the lead. Which pizza is a gut decision, which pension a cerebral one. The trouble is that few of us are the dessicated, calculating machines who populate economics textbooks: financial myopia is in part about the difficulty of controlling emotionally stirred desires for something right now, in favour of a conceptually constructed benefit in the future. There are other kinds of myopia at work, too: young people all over the country are deciding whether to revise for exams or go out partying. Exam revision is a test of the ability to rank the future ahead of the present.

Everybody suffers from financial myopia, and the extraordinary increases in life expectancy in recent decades can only make it worse. Barring state compulsion, the only defence against it is for people to learn self-control. The Oxford economist and historian Avner Offer describes how successful people learn to build "commitment strategies" to help them defer their gratification. But, like all skills, the crucial ability to delay gratification is unevenly and regressively distributed through the population.

Gloria Steinem got it close to right 25 years ago when she wrote: "Planning ahead is a measure of class. The rich and even the middle class plan for future generations, but the poor can plan ahead only a few weeks or days." In theory, rising affluence should make it easier for everyone to set aside money for the future. But with this affluence have come growing expectations, and blanket advertising: Because You're Worth It.

In the 1970s, a psychologist called Walter Mischel tested the ability of four-year-olds to control their desires: they could have either one marshmallow immediately, or two in a few minutes' time. The ones who held out for two were from more affluent homes; and, in the long term, they were more likely to get a college degree, stay out of jail and secure a good adult income than the ones who caved in immediately. In an age of hyperconsumption and instant gratification, it is harder, but even more important, to acquire the skills of self-control and deferred gratification. The political challenge is to help everyone, not just the middle class, fight their own myopia.