Our relative overvaluation of nearer experiences does a lot more than make us prone to addictions. It literally throws a curve into many experiences for which our norms are linear. In a culture where one of the basic properties of rationality is consistency, it makes us irrational at the outset.

I've discussed how the seemingly mystical idea of a will – free, more or less powerful, and somewhat brittle – describes the crux of our strategic response to temptation. The elusiveness of the will as a concept has historically come from the fact that it isn't an organ but a bargaining situation. Its brittleness comes from the often perverse inventiveness of sequential negotiators – each one the self, evaluating prospects from a shifting perspective – who are trying to maximize their prospects in a never-ending prisoner's dilemma. But however complicated the mechanism of willpower may seem, it's a neat little package compared to the other expectable consequences of intertemporal bargaining.

The most important departures from conventional utility accounting probably don't come from preference in the addiction range of durations – the urges that last for minutes to days and create the need for personal rules – and they don't come from the side effects of those personal rules themselves, even though these are considerable.