Behavioral science has long been puzzled by the experience of temptation, the resulting impulsiveness, and the variably successful control of this impulsiveness. In conventional theories, a governing faculty like the ego evaluates future choices consistently over time, discounting their value for delay exponentially, that is, by a constant rate; impulses arise when this ego is confronted by a conditioned appetite. Breakdown of Will (Ainslie 2001) presents evidence that contradicts this model. Both people and nonhuman animals spontaneously discount the value of expected events in a curve where value is divided approximately by expected delay, a hyperbolic form that is more bowed than the rational, exponential curve.

With hyperbolic discounting, options that pay off quickly will be temporarily preferred to richer but slower-paying alternatives, a phenomenon that, over periods from minutes to days, can account for impulsive behaviors, and over periods of fractional seconds can account for involuntary behaviors. Contradictory reward-getting processes can in effect bargain with each other, and stable preferences can be established by the perception of recurrent choices as test cases (precedents) in recurrent intertemporal prisoner's dilemmas. The resulting motivational pattern resembles traditional descriptions of the will, as well as of compulsive phenomena that can now be seen as side-effects of will: over-concern with precedent, intractable but circumscribed failures of self-control, a motivated (“dynamic”) unconscious, and an inability to exploit emotional rewards. Hyperbolic curves also suggest a means of reducing classical conditioning to motivated choice, the last necessary step for modeling many involuntary processes like emotion and appetite as reward-seeking behaviors; such modeling, in turn, provides a rationale for empathic reward and the “construction” of reality.

One of the reasons for adopting hyperbolic discounting is to explain preference reversals. Another is that this value structure suggests an elegant theory of the will. I examine the capacity of the theory to solve Newcomb's problem. In addition, I compare Ainslie's account with other procedural theories of choice that seem at least equally capable of accommodating reversals of preference.

Ainslie uses his hyperbolic discount model to explain a dazzling array of puzzling motivational phenomena. In so doing, he assumes that the motivational force of a given option at a given time is directly proportional to its discount-adjusted reward as assessed at that time. He overlooks three other factors which, independently of the perceived reward, can affect motivational force.

Hyperbolic theories have the fatal flaw that because of their vertical asymptote they predict irresistible choice of immediate rewards, regardless of future contingencies. They work only for simple situations. Theories incorporating intermediate unconscious choices are more flexible, but are neither exponential nor hyperbolic in their predictions. They don't solve the free will paradox, which may be just a consistent illusion.

Regret is often symptomatic of the defective decisions associated with “temporary preference” problems. It may also help overcome these defects. Outcome regret can modify the relative utilities of different payoffs. Process regret can motivate search for better decision processes or trap-evading strategies. Heightened regret may thus be functional for control of these self-defeating choices.

Ainslie is correct in arguing that the force of commitments partly depends on the predictive role of present action, but this claim can be supported independently of the analogy with interpersonal bargaining. No matter whether we conceive of the parties involved in the bargaining as interests or transient selves, the picture of the will as a competitive interaction among these parties is unconvincing.

Ainslie's insightful treatment of dynamically inconsistent choice stands in contrast to traditional views in psychology, economics, and philosophy. We comment on the form of the discounting function and on new findings regarding choice between delayed rewards. Finally, we argue that the positive correlation between temporal and probability discounting is inconsistent with the view that impulsivity represents a unitary trait.

The idea of “bundling” lesser later rewards so they outweigh smaller sooner rewards is compelling, but the sophisticated cognitive activity involved in this bundling is not yet modeled; in particular the role of language is hard to assess.

We question the behavioral premise underlying Ainslie's claims about hyperbolic discounting theory. The alleged evidence for humans can be easily explained as an artefact of experimental procedures that do not control for the credibility of payment over different time horizons. In appropriately controlled and financially motivated settings, human behavior is consistent with conventional exponential preferences.

I propose to complement Ainslie's idea of “bargaining with your future selves” with that of “shaping your past selves.” The result of such a complementation is that an action can work in two ways: (1) as a predecent for future behavior and (2) as a shaper of past behavior. I argue that this diminishes the unwanted effects of hyperbolic discounting even further.

Ainslie's Breakdown of Will contains important insights into real world self-control problems, but it loses testability to the extent that it internalizes concepts whose meaning lies in overt behavior and its consequences.

Supporters of Ainslie's model face questions about its integration with neuroscience. Although processes of value estimation may well turn out to be locally implemented, methodological reasons suggest this is less likely in the case of subpersonal “interests.”

Ainslie advances Freud's and Skinner's theories of homunculi by basing their emergent complexity on the interaction of simple algorithms. The rules of competition and cooperation of these interests are underspecified, but they provide a new way of thinking about the basic elements of conditioning, particularly conditioned stimuli (CSs).

Although Ainslie rejects cognitivism as providing an explanation of willpower, a type of nonhomuncular cognitivism is hiding in his own proposal. The key mental mechanism of aggregating individual decisions (bundled reframings) involves representation and decoupling operations encompassed within the analytic system of dual-process mental architectures.

The author of this fascinating book explores the problem of decision-making. As a basis, he uses hyperbolic discounting theory to discuss many basic assumptions related to self-control. In an accessible conversational tone, he succeeds in capturing many current problems in decision science and presents a rational framework for further work.

We agree with Ainslie's general approach to intertemporal choices and self-control. However, we argue that a concept of “will” is superfluous in explaining tradeoffs between SS (smaller and sooner) and LL (larger and later) rewards in a framework of temporal goal setting and goal aggregation. We provide an alternative framework of reference point-dependent tradeoffs between SS and LL options.

The will has generated a wider range of opinions than most phenomena, lacking as it does both an animal model and consistent behavioral correlates. It has even been held not to exist. The commentators approached my intertemporal bargaining (picoeconomic) model from many angles. Doubts about the existence of the underlying phenomenon, hyperbolic discounting, were still raised by some, but other commentators added to the evidence for it, which I regard now as overwhelming. Where mechanisms of self-control were specified, I found it possible to place them within a picoeconomic framework.

We propose that the crucial difference between human cognition and that of other species is the ability to participate with others in collaborative activities with shared goals and intentions: shared intentionality. Participation in such activities requires not only especially powerful forms of intention reading and cultural learning, but also a unique motivation to share psychological states with others and unique forms of cognitive representation for doing so. The result of participating in these activities is species-unique forms of cultural cognition and evolution, enabling everything from the creation and use of linguistic symbols to the construction of social norms and individual beliefs to the establishment of social institutions. In support of this proposal we argue and present evidence that great apes (and some children with autism) understand the basics of intentional action, but they still do not participate in activities involving joint intentions and attention (shared intentionality). Human children's skills of shared intentionality develop gradually during the first 14 months of life as two ontogenetic pathways intertwine: (1) the general ape line of understanding others as animate, goal-directed, and intentional agents; and (2) a species-unique motivation to share emotions, experience, and activities with other persons. The developmental outcome is children's ability to construct dialogic cognitive representations, which enable them to participate in earnest in the collectivity that is human cognition.

Tomasello et al. give a good account of how shared intentionality develops in children, but a much weaker one of how it might have evolved. They are unduly hasty in dismissing the emergence of language as a triggering factor. An alternative account is suggested in which language provided the spark, but thereafter language and shared intentionality coevolved.

Ignoring most published evidence on wild chimpanzees, Tomasello et al.'s claim that shared goals and intentions are uniquely human amounts to a faith statement. A brief survey of chimpanzee hunting tactics shows that group hunts are compatible with a shared goals and intentions hypothesis. The disdain of observational data in experimental psychology leads some to ignore the reality of animal cognitive achievements.