Bayesians often confuse insistence that probability judgment ought to be indeterminate (which is incompatible with Bayesian ideals) with recognition of the presence of imprecision in the determination or measurement of personal probabilities (which is compatible with these ideals). The confusion is discussed and illustrated by remarks in a recent essay by R. C. Jeffrey.

R.A.Fisher introduced the fiducial argument as a means for obtaining something from nothing. He thought that on some occasions it was legitimate to obtain a posterior probability distribution over a range of simple statistical hypotheses without commitment to a prior distribution [4].H.Jeffreys thought he could tame Fisher by casting his argument in a Bayesian mold through a derivation of the fiducial posterior from a suitably constructed ignorance prior via Bayes’ theorem and conditionalization on the data of experimentation. According to Jeffreys, (...) Fisher was using something to obtain something after all ([7],pp.381-383).D.V.Lindley furthered the process of taming by specifying allegedly necessary and sufficient conditions for the consistency of fiducial reasoning in contexts of one parameter estimation with Bayesian requirements [14]. I. Hacking exploited Lindley’s result to supply his own ingenious method for taming Fisher([5],ch. 9).T.Seidenfeld has recently demonstrated that Lindley’s conditions are insufficient for consistency and that reconstructions like Jeffreys’ or Hacking’s lead to contradiction ([15], PP. 721-727). (shrink)

Dynamic systems theory (DS) provides tools for exploring how simpler elements can interact to produce complex psychological configurations. It may, as Lewis demonstrates, provide means for explicating relationships between two reductionist approaches to overlapping sets of phenomena. The result is a description of psychological phenomena at a level that begins to achieve the richness we would hope to achieve in examining psychological life as it is experienced and explored in psychoanalysis.

Naturalism is widely regarded as the dominant philosophical worldview in the West. The prestige of science and the power of technology have driven naturalism to prominence, even as deep questions mount on all sides. In this volume of all new essays, prominent philosophers consider a wide variety of challenges to naturalism, proposing improved defenses and novel developments in this influential worldview. Some essays question whether naturalism is a unified philosophy, and try to determine how one or another variety of naturalism (...) has an advantage. Other essays defend naturalism's approaches to religion, the mind, experience, morality, and society. To ensure that naturalism has a strong future, this volume's authors are determined to help reformulate its principles for the 21st century. Among the contributors are Mario Bunge, Paul Kurtz, John Lachs, Isaac Levi, Joseph Margolis, Nicholas Rescher, John R. Shook, and other leading philosophers. (shrink)

Papers collected in this volume were originally presented at a symposium held at the University of Pennsylvania in December, 1968 and revised in the light of discussion at the symposium for publication. The contributors hold different views about the role played by induction in theories of knowledge and rational belief but many of the papers are conciliatory, reflecting no doubt a good deal of helpful communication at the symposium. For example, Frederic Schick's clearly written and informative lead article considers subjectivist, (...) empiricist, and pragmatist theories of rational belief, arguing that they are compatible theories relevant to different types of issues. Marshall Swain follows with an article which presents a general framework within which rules of rational acceptance can be constructed. An exchange between Isaac Levi and Richard Jeffrey shows that advocates of theories of acceptance and theories of partial belief may be defending complementary and not mutually exclusive theories. In the remaining three essays Henry Kyburg Jr., Gilbert Harman, and Keith Lehrer defend their own distinctive views about the nature of inductive inference and rational belief. Kyburg traces difficulties in some theories to the acceptance of the principle of conjunction which he rejects. Harman and Lehrer both see the relation of inductive inference to explanation as crucial to understanding the former and they develop theories along different lines which make use of this relation. A long and useful bibliography was prepared for the symposium by Ralph L. Slaght and revised for publication in the volume.--R. H. K. (shrink)

Plant protection problems are simulated by a system of ordinary differential equations with given initial conditions. The sensitivity and resistance of pathogen subpopulations to fungicide mixtures, fungicide weathering, plant growth, etc. are taken into consideration. The system of equations is solved numerically for each set of initial conditions and parameters of the disease and fungicide applications. Optimization algorithms were investigated and a computer program was developed for optimization of these solutions. 14 typical cases of the disease were simulated and optimized (...) in order to determine optimal fungicide treatments. The optimized strategy for fungicide application differs considerably from the commonly used method and seems to be an important new principle in plant protection. The approach developed in this study may be useful for a wide spectrum of purposes in the simulation of leaf diseases. It may also help the biologist to decrease or pinpoint experimental work and analyze its results and is perspective for plant disease control. (shrink)

Principles of rationality are invoked for several purposes: they are often deployed in explanation and prediction; they are also used to set standards for rational health for deliberating agents or to furnish blueprints for rational automata; and they are intended as guides to perplexed decision makers seeking to regulate their own attitudes and conduct. These purposes are quite different. It is far from obvious that what serves well in one capacity will do so in another. Indeed, I shall argue later (...) on in this essay that when principles of rationality are intended for use as norms for self-criticism, they cannot also serve as laws in explanation and prediction or as blueprints for rational automata. (shrink)

Isaac Levi's new book is concerned with how one can justify changing one's beliefs. The discussion is deeply informed by the belief-doubt model advocated by C. S. Peirce and John Dewey, of which the book provides a substantial analysis. Professor Levi then addresses the conceptual framework of potential changes available to an inquirer. A structural approach to propositional attitudes is proposed, which rejects the conventional view that a propositional attitude involves a relation between an agent and either a linguistic (...) entity or some other intentional object such as a proposition or set of possible worlds. The last two chapters offer an account of change in states of full belief understood as changes in commitments rather than changes in performance; one chapter deals with adding new information to a belief state, the other with giving up information. The book builds upon topics discussed in some of Levi's earlier work. It will be of particular interest to discussion theorists, epistemologists, philosophers of science, computer scientists, and cognitive psychologists. (shrink)

This major work challenges some widely held positions in epistemology - those of Peirce and Popper on the one hand and those of Quine and Kuhn on the other.

This comprehensive discussion of the problem of rational belief develops the subject on the pattern of Bayesian decision theory. The analogy with decision theory introduces philosophical issues not usually encountered in logical studies and suggests some promising new approaches to old problems."We owe Professor Levi a debt of gratitude for producing a book of such excellence. His own approach to inductive inference is not only original and profound, it also clarifies and transforms the work of his predecessors. In short, the (...) book deserves to become a classic....There is a great deal of interest in the book besides these basic matters [forumlating rules of acceptance]. Some of the most interesting chapters are those that examine the implications of such rules. The discussions of probability, generalization, and various forms of inference are brilliant and enlightening. Indeed, the problems and methods elaborated by Professor Levi in his book serve as a new foundation for the study of inductive inference."--Keith Lehrer, Nous"Levi's book is an extremely interesting report on 'tentative and speculative first steps' toward a decision-theoretic approach to inductive inference....Professor Levi is to be congratulated on his ingenious development and application of this approach...."--Richard C. Jeffrey, The Journal of Philosophy. (shrink)

Isaac Levi is one of the preeminent philosophers in the areas of pragmatic rationality and epistemology. This collection of essays constitutes an important presentation of his original and influential ideas about rational choice and belief. A wide range of topics is covered, including consequentialism and sequential choice, consensus, voluntarism of belief, and the tolerance of the opinions of others. The essays elaborate on the idea that principles of rationality are norms that regulate the coherence of our beliefs and values (...) with our rational choices. The norms impose minimal constraints on deliberation and inquiry, but they also impose demands well beyond the capacities of deliberating agents. This major collection will be eagerly sought out by a wide range of philosophers in epistemology, logic, and philosophy of science, as well as economists, decision theorists, and statisticians. (shrink)

Isaac Levi's new book develops further his pioneering work in formal epistemology, focusing on the problem of belief contraction, or how rationally to relinquish old beliefs. Levi offers the most penetrating analysis to date of this key question in epistemology, offering a completely new solution and explaining its relation to his earlier proposals. He mounts an argument in favor of the thesis that contracting a state of belief by giving up specific beliefs is to be evaluated in terms of (...) the value of the information lost by doing so. The rationale aims to be thoroughly decision theoretic. Levi spells out his goals and shows that certain types of recommendations are obtained if one seeks to promote these goals. He compares his approach to his earlier account of inductive expansion. The recommendations are for "mild contractions." These are formally the same as the "severe withdrawals" considered by Pagnucco and Rott. The rationale, however, is different. A critical part of the book concerns the elaboration of these differences. The results are relevant to accounts of the conditions under which it is legitimate to cease believing and to accounts of conditionals. Mild Contraction will be of great interest to all specialists in belief revision theory and to many students of formal epistemology, philosophy of science, and pragmatism. (shrink)

It is a commonplace that in making decisions agents often have to juggle competing values, and that no choice will maximise satisfaction of them all. However, the prevailing account of these cases assumes that there is always a single ranking of the agent's values, and therefore no unresolvable conflict between them. Isaac Levi denies this assumption, arguing that agents often must choose without having balanced their different values and that to be rational, an act does not have to be (...) optimal, only what Levi terms 'admissible'. This book explores the consequences of denying the assumption and develops a general approach to decision-making under unresolved conflict. Professor Levi discusses conflicts of value in several domains - those arising in moral dilemmas, the drawing of scientific inferences, decisions taken under uncertainty, and in social choice. In each of these he adapts his theoretical framework, showing how conflict may often be reduced though not always altogether eliminated. (shrink)

In The Enterprise of Knowledge, I proposed a general theory of rational choice which I intended as a characterization of a prescriptive theory of ideal rationality. A cardinal tenet of this theory is that assessments of expected value or expected utility in the Bayesian sense may not be representable by a numerical indicator or indeed induce an ordering of feasible options in a context of deliberation. My reasons for taking this position are related to my commitment to the inquiry-oriented approach (...) to human knowledge and valuation favored by the American pragmatists, Charles Peirce and John Dewey. A feature of any acceptable view of inquiry ought to be that during an inquiry points under dispute ought to be kept in suspense pending resolution through inquiry. (shrink)

This comprehensive discussion of the problem of rational belief develops the subject on the pattern of Bayesian decision theory. The analogy with decision theory introduces philosophical issues not usually encountered in logical studies and suggests some promising new approaches to old problems."We owe Professor Levi a debt of gratitude for producing a book of such excellence. His own approach to inductive inference is not only original and profound, it also clarifies and transforms the work of his predecessors. In short, the (...) book deserves to become a classic....There is a great deal of interest in the book besides these basic matters [forumlating rules of acceptance]. Some of the most interesting chapters are those that examine the implications of such rules. The discussions of probability, generalization, and various forms of inference are brilliant and enlightening. Indeed, the problems and methods elaborated by Professor Levi in his book serve as a new foundation for the study of inductive inference."--Keith Lehrer, Nous"Levi's book is an extremely interesting report on 'tentative and speculative first steps' toward a decision-theoretic approach to inductive inference....Professor Levi is to be congratulated on his ingenious development and application of this approach...."--Richard C. Jeffrey, The Journal of Philosophy. (shrink)

This book by one of the world's foremost philosophers in the fields of epistemology and logic offers an account of suppositional reasoning relevant to practical deliberation, explanation, prediction and hypothesis testing. Suppositions made 'for the sake of argument' sometimes conflict with our beliefs, and when they do, some beliefs are rejected and others retained. Thanks to such belief contravention, adding content to a supposition can undermine conclusions reached without it. Subversion can also arise because suppositional reasoning is ampliative. These two (...) types of nonmonotonic logic are the focus of this book. A detailed comparison of nonmonotonicity appropriate to both belief contravening and ampliative suppositional reasoning reveals important differences that have been overlooked. (shrink)

This volume presents a series of essays which investigate the nature of intellectual inquiry: what its aims are and how it operates. The startingpoint is the work of the American pragmatists C.S. Peirce and John Dewey. Inquiry according to Peirce is a struggle to replace doubt by true belief. Dewey insisted that the transformation was from an indeterminate situation to a determinate or non-problematic one. So Isaac Levi's subject is changes in doxastic commitments, which may involve changes in attitudes (...) or changes in situations in which attitudes are entangled. The question of what justifies modification of doxastic commitments is a normative one, and so may not be understandable in purely naturalistic terms."--Dust jacket. (shrink)

From one end of his philosophical work to the other, Gilles Deleuze consistently described his position as a transcendental empiricism. But just what is transcendental about Deleuze’s transcendental empiricism? And how does his position fit with the traditional empiricism articulated by Hume? In Difference and Givenness , Levi Bryant addresses these long-neglected questions so critical to an understanding of Deleuze’s thinking. Through a close examination of Deleuze’s independent work--focusing especially on Difference and Repetition-- as well as his engagement with thinkers (...) such as Kant, Mai;mon, Bergson, and Simondon, Bryant sets out to unearth Deleuze’s transcendental empiricism and to show how it differs from transcendental idealism, absolute idealism, and traditional empiricism. What emerges from these efforts is a metaphysics that strives to articulate the conditions for real existence, capable of accounting for the individual itself without falling into conceptual or essentialist abstraction. In Bryant’s analysis, Deleuze’s metaphysics articulates an account of being as process or creative individuation based on difference, as well as a challenging critique--and explanation--of essentialist substance ontologies. A clear and powerful discussion of how Deleuze’s project relates to two of the most influential strains in the history of philosophy, this book will prove essential to anyone seeking to understand Deleuze’s thought and its specific contribution to metaphysics and epistemology. (shrink)