The problem of akrasia (weakness of will)
Weakness of the will (akrasia) has remained an unsolved philosophical problem since articulated by the ancients. Why do we accord the present moment more importance than the future, when rationality demands an Archimedean impartiality between our “present and future selves”? Why would you judge an action rational, as in your interest all things considered, yet not perform it?
The problem of akrasia is one of reconciliation with our commonsense introspective knowledge that, despite our failings, we clearly can (sometimes) make ourselves do things that we believe are the better choices. We make (some) rational choices and conform our behavior accordingly. What stops us from doing so consistently and biases us for the immediate? Something limits our ability to decide, but only Freud previously formulated that the limitation consists of the leaden weight of decisions recently made.
Decision theory redefines rewardingness as including, as a feature, the time its utility is experienced. The utility function describes the decreased value of the same object enjoyed later, but it doesn’t render it rational. To the extent the timing of experience is relevant in no other respect, it isn’t rational to discount time. Why does the rational-choice assumption, that we will do what’s best for ourselves, fail so miserably when the rewards happen to occur later?
I can recollect only a single theory of why we discount future selves: Derek Parfit takes the language of “future selves” literally to maintain that they present to us as the same, in principle, as other persons’ selves, with which we identify only according to the degree of their relatedness. The cost of Parfit’s move is the concept of personhood. But while personhood doesn’t deserve to be part of our ontology, it’s a useful fiction over most of our personal transactions, failing conspicuously with regard to time discounting. We should aim to discover why.
Notice seems not to have been taken by philosophers of what would seem a scientific solution to the problem of why somewhat rational beings are so akrasic. The simple empirical answer offered is that we have a tiny daily ration of willpower. Rational beings can overcome the tendency to discount time by exerting will power, but they can only do it a few times a day. Our rationality is limited by our ability to exercise willpower, which is based on a measurable physical energy source—partly replenished by consuming glucose. The toll decision fatigue takes on people is shown by the declining performances on real-life judicial issues, resulting in a change from 70% to 10% favorable decisions between the beginning and end of the day.
Ego depletion and free will
Why is there resistance to recognizing that decisions become harder the more of them you make? While decision fatigue comports with the introspection that we can make ourselves do some things, it conflicts with our intuition that we can always do what we want. Ego-depletion phenomena present yet another breakdown of the concept of compatibilist free will.
Next essay in series: Implications for the structure of government, welfare economics, and even psychotherapy.