There was a long tradition in philosophy according to which good reasoning had to be deductively valid. However, that tradition began to be questioned in the 1960’s, and is now thoroughly discredited. What caused its downfall was the recognition that many familiar kinds of reasoning are not deductively valid, but clearly confer justification on their conclusions. Here are some simple examples.

Pollock describes an exciting theory of rationality and its partial implementation in OSCAR, a computer system whose descendants will literally be persons.

Presenting an analytical and critical study of the contemporary adult educator, Paulo Freire, this book deals with all aspects of his thought, placing at the centre of consideration his educational philosophy.

This third edition, now available in paperback, is a follow up to the author's classic Boolean-Valued Models and Independence Proofs in Set Theory. It provides an exposition of some of the most important results in set theory obtained in the 20th century: the independence of the continuum hypothesis and the axiom of choice.

Practical reasoning aims at deciding what actions to perform in light of the goals a rational agent possesses. This has been a topic of interest in both philosophy and artificial intelligence, but these two disciplines have produced very different models of practical reasoning. The purpose of this paper is to examine each model in light of the other and produce a unified model adequate for the purposes of both disciplines and superior to the standard models employed by either.The philosophical (decision-theoretic) (...) model directs activity by evaluating acts one at a time in terms of their expected utilities. It is argued that, except in certain special cases, this constitutes an inadequate theory of practical reasoning leading to intuitively incorrect action prescriptions. Acts must be viewed as parts of plans, and plans evaluated as coherent units rather than piecemenal in terms of the acts comprising them. Rationality dictates choosing acts by first choosing the plans prescribing them. Plans, in turn, are compared by looking at their expected values. However, because plans can be embedded in one another, we cannot select plans just by maximizing expected values. Instead, we must employ a more complex criterion here named coextendability. (shrink)

When your word processor or email program is running on your computer, this creates a "virtual machine” that manipulates windows, files, text, etc. What is this virtual machine, and what are the virtual objects it manipulates? Many standard arguments in the philosophy of mind have exact analogues for virtual machines and virtual objects, but we do not want to draw the wild metaphysical conclusions that have sometimes tempted philosophers in the philosophy of mind. A computer file is not made of (...) epiphenomenal ectoplasm. I argue instead that virtual objects are "supervenient objects". The stereotypical example of supervenient objects is the statue and the lump of clay. To this end I propose a theory of supervenient objects. Then I turn to persons and mental states. I argue that my mental states are virtual states of a cognitive virtual machine implemented on my body, and a person is a supervenient object supervening on his cognitive virtual machine. (shrink)

If we imagine a chess-board with alternate blue and red squares, then this is something in which the individual red and blue areas allow themselves to be distinguished from each other in juxtaposition, and something similar holds also if we imagine each of the squares divided into four smaller squares also alternating between these two colours. If, however, we were to continue with such divisions until we had exceeded the boundary of noticeability for the individual small squares which result, then (...) it would no longer be possible to apprehend the individual red and blue areas in their respective positions. But would we then see nothing at all? Not in the least; rather we would see the whole chessboard as violet, i.e. apprehend it as something that participates simultaneously in red and blue. (shrink)

As his editor John L. Stanley points out, Georges Sorel was "that fascinating polymath." This volume, the third in his selected works in the English language published by Transaction, emphasizes Sorel's extraordinary writings in the philosophy of science, religion, culture, and art. For those who know Sorel only as author of Reflections on Violence, the present volume will come as a forceful reminder of the range and depth of Sorelian efforts to construct a world view. Sorel is throughout concerned (...) with the moral development of human beings. In this sense, his writings on politics are of a piece with his writings on religion, "facticity" of human history and society. Sorel's earliest writings were on religion, and key portions of that period are reflected in selections here. And he went on from there to study the sociology of science, the ways in which science fits into the cultural history of civilization and present day social relationships of industrial society. Stanley provides a profound framework based on two decades of close study and translation of Sorel's texts. He helps to explain how the partial theories of Sorel lead to holistic intellectual consequences, how the psychological method does not foreclose political activism, and how historical limits can be transformed against a background of aesthetics or considerations of taste. He shows that Sorel comes as a close as Manheim and Simmel and Durkheim to the creation of a modern social science--albeit he lacks the overall philosophical theorems of people like Marx and Weber. In Sorel we have a first-class mind at work. And in Stanley, we have a first-class analyst at work. Together, the volume adds up to something special for the political scientist, sociologist, art historian, theologian--in short for those to whom the ideal of a human science endures. John L. Stanley is professor of political science at the University of California at Riverside. He is the author of The Sociology of Virtue: The Political and Social Theories of Georges Sorel. He has written many articles and reviews on the history of European political theory. With his wife, Charlotte Stanley, he has been long engaged in the translation of the works of Georges Sorel. (shrink)

Stuart Russell [14] describes rational agents as --œthose that do the right thing--�. The problem of designing a rational agent then becomes the problem of figuring out what the right thing is. There are two approaches to the latter problem, depending upon the kind of agent we want to build. On the one hand, anthropomorphic agents are those that can help human beings rather directly in their intellectual endeavors. These endeavors consist of decision making and data processing. An agent that (...) can help humans in these enterprises must make decisions and draw conclusions that are rational by human standards of rationality. Anthropomorphic agents can be contrasted with goal-oriented agents --” those that can carry out certain narrowly-defined tasks in the world. Here the objective is to get the job done, and it makes little difference how the agent achieves its design goal. (shrink)

For this second edition, the editors have returned to Austin's original lecture notes, amending the printed text where it seemed necessary.

Princeton University Press, 1982. This book is out of print, but can be downloaded as a pdf file (5 MB).

This exceptionally successful survey text introduces the teachings and practice of Islam from its earliest origins up to its contemporary practice. John L. Esposito, an internationally renowned expert on Islam, traces the development of Islam and its impact on world history and politics.Lucidly written and expansive in scope, Islam: The Straight Path, Updated Fifth Edition, provides keen insight into one of the world's least understood religions. It is ideally suited for use in courses on Islam, world religions, comparative religions, (...) and Middle East history and culture.A FREE 6-month subscription to Oxford Islamic Studies Online, edited by John L. Esposito, is included with the purchase of every new copy of this text. (shrink)

Two seemingly complementary trends stand out currently in school science education in the United States: one is the increased emphasis on inquiry activities in classrooms, and the other is the high level of attention given to student understanding of the nature of science. This essay looks at the range of activities that fall within the first trend, noting, in particular, the growing popularity of inquiry activities that engage students in engineering-type tasks. The potential for public disengagement from science and technology (...) issues is described as a result of the continued juxtaposition of these sorts of inquiry activities with our current, idealized portrayals of the nature of science—the emphasis of the second trend. Drawing on Dewey's instrumental theory of knowledge, an alternative way of thinking about science is offered that would not only provide for a more authentic understanding of science, but also invite much needed public participation in the broad governance of science in modern-day democratic societies. (shrink)

Imagine yourself sitting on your front porch, sipping your morning coffee and admiring the scene before you. You see trees, houses, people, automobiles; you see a cat running across the road, and a bee buzzing among the flowers. You see that the flowers are yellow, and blowing in the wind. You see that the people are moving about, many of them on bicycles. You see that the houses are painted different colors, mostly earth tones, and most are one-story but a (...) few are two-story. It is a beautiful morning. Thus the world interfaces with your mind through your senses. There is a strong intuition that we are not disconnected from the world. We and the other things we see around us are part of a continuous whole, and we have direct access to them through vision, touch, etc. However, the philosophical tradition tries to drive a wedge between us and the world by insisting that the information we get from perception is the result of inference from indirect evidence that is about how things look and feel to us. The philosophical problem of perception is then to explain what justifies these inferences. We will focus on visual perception. Figure one presents a crude diagram of the cognitive system of an agent capable of forming beliefs on the basis of visual perception. Cognition begins with the stimulation of the rods and cones on the retina. From that physical input, some kind of visual processing produces an introspectible visual image. In response to the production of the visual image, the cognizer forms beliefs about his or her surroundings. Some beliefs the perceptual beliefs are formed as direct responses to the visual input, and other beliefs are inferred from the perceptual beliefs. The perceptual beliefs are, at the very least, caused or causally influenced by having the image. This is signified by the dashed arrow marked with a large question mark. We will refer to this as the mystery link. Figure one makes it apparent that in order to fully understand how knowledge is based on perception, we need three different theories.. (shrink)

subsets X of A for which ∃x (x ∈ A). The set of functions from A to B is denoted by BA.

The principle of set theory known as the Axiom of Choice has been hailed as “probably the most interesting and, in spite of its late appearance, the most discussed axiom of mathematics, second only to Euclid's axiom of parallels which was introduced more than two thousand years ago” (Fraenkel, Bar-Hillel & Levy 1973, §II.4). The fulsomeness of this description might lead those unfamiliar with the axiom to expect it to be as startling as, say, the Principle of the Constancy of (...) the Velocity of Light or the Heisenberg Uncertainty Principle. But in fact the Axiom of Choice as it is usually stated appears humdrum, even self-evident. For it amounts to nothing more than the claim that, given any collection of mutually disjoint nonempty sets, it is possible to assemble a new set — a transversal or choice set — containing exactly one element from each member of the given collection. Nevertheless, this seemingly innocuous principle has far-reaching mathematical consequences — many indispensable, some startling — and has come to figure prominently in discussions on the foundations of mathematics. It (or its equivalents) have been employed in countless mathematical papers, and a number of monographs have been exclusively devoted to it. (shrink)

The question addressed in this paper is how the degree of justification of a belief is determined. A conclusion may be supported by several different arguments, the arguments typically being defeasible, and there may also be arguments of varying strengths for defeaters for some of the supporting arguments. What is sought is a way of computing the “on sum” degree of justification of a conclusion in terms of the degrees of justification of all relevant premises and the strengths of all (...) relevant reasons. (shrink)

IN THEIR WELL-KNOWN PAPER, Kochen and Specker (1967) introduce the concept of partial Boolean algebra (pBa) and show that certain (finitely generated) partial Boolean algebras arising in quantum theory fail to possess morphisms to any Boolean algebra (we call such pBa's intractable in the sequel). In this note we begin by discussing partial..

A weak form of intuitionistic set theory WST lacking the axiom of extensionality is introduced. While WST is too weak to support the derivation of the law of excluded middle from the axiom of choice, we show that beefing up WST with moderate extensionality principles or quotient sets enables the derivation to go through.

Logical Options introduces the extensions and alternatives to classical logic which are most discussed in the philosophical literature: many-sorted logic, second-order logic, modal logics, intuitionistic logic, three-valued logic, fuzzy logic, and free logic. Each logic is introduced with a brief description of some aspect of its philosophical significance, and wherever possible semantic and proof methods are employed to facilitate comparison of the various systems. The book is designed to be useful for philosophy students and professional philosophers who have learned some (...) classical first-order logic and would like to learn about other logics important to their philosophical work. (shrink)

5.5. Every topos is linguistic: the equivalence theorem.

ABSTRACT: It is characteristic of a continuum that it be “all of one piece”, in the sense of being inseparable into two (or more) disjoint nonempty parts. By taking “part” to mean open (or closed) subset of the space, one obtains the usual topological concept of connectedness . Thus a space S is defined to be connected if it cannot be partitioned into two disjoint nonempty open (or closed) subsets – or equivalently, given any partition of S into two open (...) (or closed) subsets, one of the members of the partition must be empty. This holds, for example, for the space R of real numbers and for all of its open or closed intervals. Now a truly radical condition results from taking the idea of being “all of one piece” literally, that is, if it is taken to mean inseparability into any disjoint nonempty parts, or subsets, whatsoever . A space S satisfying this condition is called cohesive or indecomposable. While the law of excluded middle of classical logic reduces indecomposable spaces to the trivial empty space and one-point spaces, the use of intuitionistic logic makes it possible not only for nontrivial cohesive spaces to exist, but for every connected space to be cohesive.In this paper I describe the philosophical background to cohesiveness as well as some of the ways in which the idea is modelled in contemporary mathematics. (shrink)

This Element is an exposition of second- and higher-order logic and type theory. It begins with a presentation of the syntax and semantics of classical second-order logic, pointing up the contrasts with first-order logic. This leads to a discussion of higher-order logic based on the concept of a type. The second Section contains an account of the origins and nature of type theory, and its relationship to set theory. Section 3 introduces Local Set Theory, an important form of type theory (...) based on intuitionistic logic. In Section 4 number of contemporary forms of type theory are described, all of which are based on the so-called 'doctrine of propositions as types'. We conclude with an Appendix in which the semantics for Local Set Theory - based on category theory - is outlined. (shrink)

Princeton University Press, 984. This book is out of print, but can be downloaded as a pdf file (3.9 MB).

This essay is an attempt to sketch the evolution of type theory from its beginnings early in the last century to the present day. Central to the development of the type concept has been its close relationship with set theory to begin with and later its even more intimate relationship with category theory. Since it is effectively impossible to describe these relationships (especially in regard to the latter) with any pretensions to completeness within the space of a comparatively short article, (...) I have elected to offer detailed technical presentations of just a few important instances. (shrink)

The practice of personal autonomy is a dynamic event that consists of a vital interplay between the self, socio-cultural reality, meaning, and being epistemically responsible. Autonomy is not static, something that we simply possess by virtue of a status as 'rational beings'. Therefore, in this dissertation, I examine the traditional notion of autonomy as it has been developed by Kant and subsequently influenced the current debate between 'liberals' and 'communitarians'. Primarily from the standpoint of the critiques developed by Charles Taylor, (...) I argue that the fundamental disagreement between these two camps is over the concept of the self. While this landscape stands divided, some middle ground can be found in the work of Joseph Raz, who postulated the need for a combination of individual abilities and an autonomy-supporting environment as necessary conditions for practicing personal autonomy. His characterization of 'personal autonomy', distinct from Kantian autonomy, forms the underlying paradigm for this work. (shrink)

As a preliminary to the modern theory of measurement with which this paper is chiefly concerned, it is desirable to review a few of the characteristics and implications of classical physics to illustrate the far reaching changes that have taken place in our conception of nature as the result of the development of quantum mechanics.