Distinctions have been proposed between systems of reasoning for centuries. This article distills properties shared by many of these distinctions and characterizes the resulting systems in light of recent findings and theoretical developments. One system is associative because its computations reflect similarity structure and relations of temporal contiguity. The other is "rule based" because it operates on symbolic structures that have logical content and variables and because its computations have the properties that are normally assigned to rules. The systems serve (...) complementary functions and can simultaneously generate different solutions to a reasoning problem. The rule-based system can suppress the associative system but not completely inhibit it. The article reviews evidence in favor of the distinction and its characterization. (shrink)

This target article presents a new computational theory of explanatory coherence that applies to the acceptance and rejection of scientific hypotheses as well as to reasoning in everyday life, The theory consists of seven principles that establish relations of local coherence between a hypothesis and other propositions. A hypothesis coheres with propositions that it explains, or that explain it, or that participate with it in explaining other propositions, or that offer analogous explanations. Propositions are incoherent with each other if they (...) are contradictory, Propositions that describe the results of observation have a degree of acceptability on their own. An explanatory hypothesis is acccpted if it coheres better overall than its competitors. The power of the seven principles is shown by their implementation in a connectionist program called ECHO, which treats hypothesis evaluation as a constraint satisfaction problem. Inputs about the explanatory relations are used to create a network of units representing propositions, while coherende and incoherence relations are encoded by excitatory and inbihitory links. ECHO provides an algorithm for smoothly integrating theory evaluation based on considerations of explanatory breadth, simplicity, and analogy. It has been applied to such important scientific cases as Lovoisier's argument for oxygen against the phlogiston theory and Darwin's argument for evolution against creationism, and also to cases of legal reasoning. The theory of explanatory coherence has implications for artificial intelligence, psychology, and philosophy. (shrink)

Self-control, so important in the theory and practice of psychology, has usually been understood introspectively. This target article adopts a behavioral view of the self (as an abstract class of behavioral actions) and of self-control (as an abstract behavioral pattern dominating a particular act) according to which the development of self-control is a molar/molecular conflict in the development of behavioral patterns. This subsumes the more typical view of self-control as a now/later conflict in which an act of self-control is a (...) choice of a larger but later reinforcer over a smaller but sooner reinforcer. If at some future time the smaller-sooner reinforcer will be more valuable than the larger-later reinforcer, self-control may be achieved through a commitment to the largerlater reinforcer prior to that point. According to some, there is a progressive internalization of commitment in the development of self-control. This presents theoretical and empirical problems. In two experiments temporal patterning of choices increased self-control. (shrink)