Akrasia is the tendency to act against your own long-term interests, and is a problem doubtless only too familiar to us all. In his book "Breakdown of Will", psychologist George C Ainslie sets out a theory of how akrasia arises and why we do the things we do to fight it. His extraordinary proposal takes insights given us by economics into how conflict is resolved and extends them to conflicts of different agencies within a single person, an approach he terms "picoeconomics". The foundation is a curious discovery from experiments on animals and people: the phenomenon of hyperbolic discounting.
We all instinctively assign a lower weight to a reward further in the future than one close at hand; this is "discounting the future". We don't just account for a slightly lower probability of recieving a more distant award, we value it at inherently less for being further away. It's been an active debate on overcomingbias.com whether such discounting can be rational at all. However, even if we allow that discounting can be rational, the way that we and other animals do it has a structure which is inherently irrational: the weighting we give to a future event is, roughly, inversely proportional to how far away it is. This is hyperbolic discounting, and it is an empirically very well confirmed result.
I say "inherently irrational" because it is inconsistent over time: the relative cost of a day's wait is considered differently whether that day's wait is near or far. Looking at a day a month from now, I'd sooner feel awake and alive in the morning than stay up all night reading comments on lesswrong.com. But when that evening comes, it's likely my preferences will reverse; the distance to the morning will be relatively greater, and so my happiness then will be discounted more strongly compared to my present enjoyment, and another groggy morning will await me. To my horror, my future self has different interests to my present self, as surely as if I knew the day a murder pill would be forced upon me.
If I knew that a murder pill really would be forced upon me on a certain date, after which I would want nothing more than to kill as many people as possible as gruesomly as possible, I could not sit idly by waiting for that day to come; I would want to do something now to prevent future carnage, because it is not what the me of today desires. I might attempt to frame myself for a crime, hoping that in prison my ability to go on a killing spree would be contained. And this is exactly the behavour we see in people fighting akrasia: consider the alcoholic who moves to a town in which alcohol is not sold, anticipating a change in desires and deliberately constraining their own future self. Ainslie describes this as "a relationship of limited warfare among successive selves".
And it is this warfare which Ainslie analyses with the tools of behavioural economics. His analysis accounts for the importance of making resolutions in defeating akrasia, and the reasons why a resolution is easier to keep when it represents a "bright clear line" that we cannot fool ourselves into thinking we haven't crossed when we have. It also discusses the dangers of willpower, and the ways in which our intertemporal bargaining can leave us acting against both our short-term and our long-term interests.
I can't really do more than scratch the surface on how this analysis works in this short article; you can read more about the analysis and the book on Ainslie's website, picoeconomics.org. I have the impression that defeating akrasia is the number one priority for many lesswrong.com readers, and this work is the first I've read that really sets out a mechanism that underlies the strange battles that go on between our shorter and longer term interests.
I haven't worked out the mathematical details, but qualitatively it seems to me that we discount the future more than expected because we don't know what our desires will be like in the future (but nevertheless want to maximize the happiness of our future selves, whatever that may consist in). This means whatever action I take now to benefit my future self has an extra decrement in (present) utility because of my uncertainty in how much the future self will be benefited. And then there's the higher-order effect that the future self may have turned into someone the present self doesn't want to benefit (maybe they want to gruesomely murder many people).
For example, I might pay less for tickets to the Bayreuth festival five years from now than I would for this year's tickets not only because of the loss of interest income, chance that the festival won't be around in five years, etc., but also because of the chance that I simply won't like Wagner as well in five years as I do now. (Of course, theater tickets are easily resalable, which should ameliorate the effect somewhat in that case.)
Therefore, since the murder pill is an example where you know exactly what your values will be at a future point, it may not be relevant to many more common instances of akrasia.
There are many different ways in which we could discount the future. The problem with almost all of them -- including the "hyperbolic" discounting Ainslie describes -- is not (necessarily) the mere fact that they discount, nor that they discount too much, but that they discount inconsistently: given times t1,t2,t3,t4, the relative importance of times t3 and t4 as seen from t1 is not the same as their relative importance as seen from t4. Or, to put it differently: if I apply t2-as-seen-from-t1 discounting together with t3-as-seen-from-t2 discounti... (read more)