The degree to which information is encoded explicitly in a representation is related to the computational cost of recovering or using the information. Knowledge that is implicit in a system need not be represented at all, even implicitly, if the cost of recurring it is prohibitive.

Are people rational? This question was central to Greek thought and has been at the heart of psychology and philosophy for millennia. This book provides a radical and controversial reappraisal of conventional wisdom in the psychology of reasoning, proposing that the Western conception of the mind as a logical system is flawed at the very outset. It argues that cognition should be understood in terms of probability theory, the calculus of uncertain reasoning, rather than in terms of logic, the calculus (...) of certain reasoning. (shrink)

What exactly is reasoning? Like many other philosophers, I shall endorse a broadly causal conception of reasoning. Reasoning is a causal process, in which one mental event (say, one’s accepting the conclusion of a certain argument) is caused by an antecedent mental event (say, one’s considering the premises of the argument). Just like causal accounts of action and causal accounts of perception, causal accounts of reasoning have to confront a version of what has come to be known as the problem (...) of deviant causal chains. In this paper, I shall propose an account of the nature of reasoning, incorporating a solution to the specific version of the deviant causal chains problem that arises for accounts of reasoning. One striking feature of my solution is that it requires that certain normative facts are causally efficacious. It might be thought that this feature will make my account incompatible with any plausibly naturalistic approach to understanding the mind. I shall argue that this is not so: my account of the nature of reasoning is quite compatible with plausible versions of naturalism. (shrink)

It is sometimes suggested that there are two kinds of reasoning: inferential reasoning and non-inferential reasoning. However, it is not entirely clear what the difference between these two kinds of reasoning is. In this paper, I try to answer the question what this difference is. I first discuss three answers to this question that I argue are unsatisfactory. I then give a different answer to this question, and I argue that this answer is satisfactory. I end by showing that this (...) answer can help to resolve some disagreements in which the difference between inferential and noninferential reasoning plays a role. (shrink)

The thirty-five chapters in this book describe various judgmental heuristics and the biases they produce, not only in laboratory experiments but in important...

Change in View offers an entirely original approach to the philosophical study of reasoning by identifying principles of reasoning with principles for revising one's beliefs and intentions and not with principles of logic. This crucial observation leads to a number of important and interesting consequences that impinge on psychology and artificial intelligence as well as on various branches of philosophy, from epistemology to ethics and action theory. Gilbert Harman is Professor of Philosophy at Princeton University. A Bradford Book.

The degree to which information is encoded explicitly in a representation is related to the computational cost of recovering or using the information. Knowledge that is implicit in a system need not be represented at all, even implicitly, if the cost of recovering it is prohibitive.

What role, if any, does formal logic play in characterizing epistemically rational belief? Traditionally, belief is seen in a binary way - either one believes a proposition, or one doesn't. Given this picture, it is attractive to impose certain deductive constraints on rational belief: that one's beliefs be logically consistent, and that one believe the logical consequences of one's beliefs. A less popular picture sees belief as a graded phenomenon.

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)

Mind and Supermind offers an alternative perspective on the nature of belief and the structure of the human mind. Keith Frankish argues that the folk-psychological term 'belief' refers to two distinct types of mental state, which have different properties and support different kinds of mental explanation. Building on this claim, he develops a picture of the human mind as a two-level structure, consisting of a basic mind and a supermind, and shows how the resulting account sheds light on a number (...) of puzzling phenomena and helps to vindicate folk psychology. Topics discussed include the function of conscious thought, the cognitive role of natural language, the relation between partial and flat-out belief, the possibility of active belief formation, and the nature of akrasia, self-deception and first-person authority. This book will be valuable for philosophers, psychologists and cognitive scientists. (shrink)

Scientific reasoning is—and ought to be—conducted in accordance with the axioms of probability. This Bayesian view—so called because of the central role it accords to a theorem first proved by Thomas Bayes in the late eighteenth ...

What theory should we accept from the practical point of view, or accept as a basis for guiding our actions, if we don’t know which theory is true, and if there are too many plausible alternative theories for us to take them all into consideration? This question is the theme of the first three parts of this dissertation. I argue that the problem of theory acceptance, so understood, is a problem of practical rationality, and hence that the appropriate grounds for (...) theory acceptance are practical considerations. I argue for a number of principles of theory acceptance, and I explore the implications of these principles for the acceptance both of descriptive theories and evaluative theories. (shrink)

About the book: This book explores the idea that we have two minds - automatic, unconscious, and fast, the other controlled, conscious, and slow. In recent years there has been great interest in so-called dual-process theories of reasoning and rationality. According to such theories, there are two distinct systems underlying human reasoning - an evolutionarily old system that is associative, automatic, unconscious, parallel, and fast, and a more recent, distinctively human system that is rule-based, controlled, conscious, serial, and slow. Within (...) the former, processes the former, processes are held to be innate and to use heuristics that evolved to solve specific adaptive problems. In the latter, processes are taken to be learned, flexible, and responsive to rational norms. (shrink)

Is our case strong enough to go to trial? Will interest rates go up? Can I trust this person? Such questions - and the judgments required to answer them - are woven into the fabric of everyday experience. This book, first published in 2002, examines how people make such judgments. The study of human judgment was transformed in the 1970s, when Kahneman and Tversky introduced their 'heuristics and biases' approach and challenged the dominance of strictly rational models. Their work highlighted (...) the reflexive mental operations used to make complex problems manageable and illuminated how the same processes can lead to both accurate and dangerously flawed judgments. The heuristics and biases framework generated a torrent of influential research in psychology - research that reverberated widely and affected scholarship in economics, law, medicine, management, and political science. This book compiles the most influential research in the heuristics and biases tradition since the initial collection of 1982. (shrink)

Reasons and reasoning were central to the work of Paul Grice, one of the most influential and admired philosophers of the late twentieth century. In the John Locke Lectures that Grice delivered in Oxford at the end of the 1970s, he set out his fundamental thoughts about these topics; Aspects of Reason is the long-awaited publication of those lectures. This immensely rich work, powerfully evocative of the mind of its author, will refresh and illuminate discussions in many areas of contemporary (...) philosophy. (shrink)