This new edition of the classic Contemporary Theories of Knowledge has been significantly updated to include analyses of the recent literature in epistemology.

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.

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

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)

A rational agent has beliefs reflecting the state of its environment, and likes or dislikes Its situation. When it finds the world not entirely to Its liking, it tries to change that. We can, accordingly, evaluate a system of cognition in terms of its probable success in bringing about situations that are to the agent's liking. In doing this we are viewing practical reasoning from “the design stance.” It is argued that a considerable amount of the structure of rationality can (...) be elicited as providing the only apporant solutions to various logical and feasibility problems that arise in the course of trying to design a rational agent that satisfies this design specification. (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)

The strategy of this paper is to throw light on rational cognition and epistemic justification by examining irrationality. Epistemic irrationality is possible because we are reflexive cognizers, able to reason about and redirect some aspects of our own cognition. One consequence of this is that one cannot give a theory of epistemic rationality or epistemic justification without simultaneously giving a theory of practical rationality. A further consequence is that practical irrationality can affect our epistemic cognition. I argue that practical irrationality (...) derives from a general difficulty we have in overriding built-in shortcut modules aimed at making cognition more efficient, and all epistemic irrationality can be traced to this same source. A consequence of this account is that a theory of rationality is a descriptive theory, describing contingent features of a cognitive architecture, and it forms the core of a general theory of “voluntary” cognition — those aspects of cognition that are under voluntary control. It also follows that most of the so-called “rules for rationality” that philosophers have proposed are really just rules describing default (non- reflexive) cognition. It can be perfectly rational for a reflexive cognizer to break these rules. The “normativity” of rationality is a reflection of a built-in feature of reflexive cognition — when we detect violations of rationality, we have a tendency to desire to correct them. This is just another part of the descriptive theory of rationality. Although theories of rationality are descriptive, the structure of reflexive cognition gives philosophers, as human cognizers, privileged access to certain aspects of rational cognition. Philosophical theories of rationality are really scientific theories, based on inference to the best explanation, that take contingent introspective data as the evidence to be explained. (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)

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)

It has long been claimed that Homo sapiens is the only species that has language, but only recently has it been recognized that humans also have an unusual pattern of growth and development. Social mammals have two stages of pre-adult development: infancy and juvenility. Humans have two additional prolonged and pronounced life history stages: childhood, an interval of four years extending between infancy and the juvenile period that follows, and adolescence, a stage of about eight years that stretches from juvenility (...) to adulthood. We begin by reviewing the primary biological and linguistic changes occurring in each of the four pre-adult ontogenetic stages in human life history. Then we attempt to trace the evolution of childhood and juvenility in our hominin ancestors. We propose that several different forms of selection applied in infancy and childhood; and that, in adolescence, elaborated vocal behaviors played a role in courtship and intrasexual competition, enhancing fitness and ultimately integrating performative and pragmatic skills with linguistic knowledge in a broad faculty of language. A theoretical consequence of our proposal is that fossil evidence of the uniquely human stages may be used, with other findings, to date the emergence of language. If important aspects of language cannot appear until sexual maturity, as we propose, then a second consequence is that the development of language requires the whole of modern human ontogeny. Our life history model thus offers new ways of investigating, and thinking about, the evolution, development, and ultimately the nature of human language. (shrink)

Summary The Copernican system was condemned as heretical by a decree of the Roman Inquisition in 1633. This decree was effectively, though not officially, withdrawn in 1757, after which date Catholic astronomers felt themselves free to accept and propagate the system without reserve. Between these dates their attitudes varied greatly. In France the decree was never promulgated and was legally unenforceable. Astronomers could be Copernican without any fear of consequences and most of them were, though some, out of respect for (...) the Church, refrained from declaring themselves publicly. In Italy the possible risks were greater, but a few Copernican or near-Copernican works were published without hostile reactions. The ecclesiastical authorities were tolerant and made little positive effort to enforce conformity. By 1744, the system was being freely propagated in Rome itself. (shrink)

The strategy of this paper is to throw light on rational cognition and epistemic justification by examining irrationality. Epistemic irrationality is possible because we are reflexive cognizers, able to reason about and redirect some aspects of our own cognition. One consequence of this is that one cannot give a theory of epistemic rationality or epistemic justification without simultaneously giving a theory of practical rationality. A further consequence is that practical irrationality can affect our epistemic cognition. I argue that practical irrationality (...) derives from a general difficulty we have in overriding built-in shortcut modules aimed at making cognition more efficient, and all epistemic irrationality can be traced to this same source. A consequence of this account is that a theory of rationality is a descriptive theory, describing contingent features of a cognitive architecture, and it forms the core of a general theory of “voluntary” cognition — those aspects of cognition that are under voluntary control. It also follows that most of the so-called “rules for rationality” that philosophers have proposed are really just rules describing default (non- reflexive) cognition. It can be perfectly rational for a reflexive cognizer to break these rules. The “normativity” of rationality is a reflection of a built-in feature of reflexive cognition — when we detect violations of rationality, we have a tendency to desire to correct them. This is just another part of the descriptive theory of rationality. Although theories of rationality are descriptive, the structure of reflexive cognition gives philosophers, as human cognizers, privileged access to certain aspects of rational cognition. Philosophical theories of rationality are really scientific theories, based on inference to the best explanation, that take contingent introspective data as the evidence to be explained. (shrink)

This path-breaking book reconceptualizes our understanding of political tolerance as well as of its foundations.

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)

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

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)

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.

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)

Language, like other human traits, could only have evolved during one or more stages of development. We enlist the theoretical framework of human life history to account for certain aspects of linguistic evolution, with special reference to initial phases in the process. It is hypothesized that selection operated at several developmental stages, the earlier ones producing new behaviors that were reinforced by additional, and possibly more powerful, forms of selection during later stages, especially adolescence and early adulthood. Peer commentaries have (...) provided opportunities to explain human life history more comprehensively, and to add details to our account of spoken language. We made no attempt to explain syntax in the target article, but we propose here that selection for “vocal plumage” may have increased our species’ capacity for utterance complexity, a development that would have benefited all levels of language. (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..

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.

A four-dimensional operator is shown to contain the operator-generators for rotation, scale, reflections, and boosts. The hypothesis is advanced that a physical system changes under this operator by at most a complex phase factor due to invariance against the choice of menial frame. A canonical transform gives a simple relation between space-time and energy-momentum. The basic conserved quantity is a four-dimensional angular momentum and/or coupling constant. The differential of this function contains a second-order differential product which is constrained as a (...) power series in the independent variable. The analysis explores the consequences of the model and shows its degree of correspondence to the standard models. (shrink)

Why should one believe that conscious awareness is solely the result of organizational complexity? What is the connection between consciousness and combinatorics: transformation of quantity into quality? The claim that the former is reducible to the other seems unconvincing—as unlike as chalk and cheese! In his book1 Penrose is at least attempting to compare like with like: the enigma of consciousness with the progress of physics.

In lieu of an abstract, here is a brief excerpt of the content:POMPONAZZI'S CRITIQUE OF AQUCNAS'S ARGUMENTS FOR THE :IMMORTALITY OF THE SOUL JOHN L. TRELOAR, S.J. Marquette University Milwaukee, Wisconsin I. lntJroWi.wtion IN 'JiHE COURSE of hls discussion on the immortality of the soul, Pietro Pomponazzi systematically critiques the Pfatonic, Avel'IJ'IOist, and Thomistic positions concerning this perennial problem iin the philosophy of human nature. Pomponiazzi's Tractatrus de irnrmortalitate animae 1 is inteirestin!g from three methodological standpoints: (1) the criteria (...) Pomponazzi uses to ev:aluate the various positions, (2) Pomponazzi 's attempt to redefine the probtlem of immortality in fo:gica;l terms, and (8) his analysis of previous positions. In this Renaissance treatise one finds an excellent example of the infliuence of method on the dev:elopment of an idea. This article wiihl eX'amine and ev:aluate Pomponazzi's analy,s:i.s of Thomas A:quiinas's aJ.'gument for the immortality of the soul showing how Pomponazzi''S irefo:rnnula;bion puts the Thomistic argument in a context completely differoort fmm whait Thomas himself intended. Although this ipaper treats a historical pr01blem, its mai:i.n oibject is to show how the fo:tmulation of phifosophical critema and,questions influences how one handles a topic 1 and 1 The standard Latin text of the Tractatus is: Petrus Pomponatus, Tractatus de immortalitate animae, ed. Gianfranco Morra (Bologna: Nanni and Fiammeghi, 1954). The English translations used in this article are from Ernst Cassirer et al., eds. The Renaissance Philosophy of Man (Chicago: University of Chicago Press, 1948). A complete translation of the Tractatus by William Henry Hay II, revised by John Herman Randall, Jr., and annotated by Paul Oskar Kristeller, appears on pp. 280-381. 458 454 JOHN L. TRELOAR, S.J, what one says about prewous solutions to a problem. This article, then, studies a rphi1osophica1l methodology as much as it arppraises Pomrponazzi and Aquinas.2 Eady in the Tractatus de immortalitate animae Pomponazzi 'es'tia;bJishes the dual cr1iter:ia for judging the adequacy of au p!i.'evious arguments ]or the immortaJl~ty of the,soul. First, "Leaving aside revefaition and miracles, and remaining entirely within natmal limits," 3 what can be said concerrning the immortality of the soul? Second, "what... was Aristotle's opin~on on the same question "?4 These criteria function as the limiting conditions that determine the adequacy of any argument :for immortality; Pomponazzi employs these criteria riJgm~ously to test whether previious a1rguments are adeqU'ate. Pomponazzi's attempt to l'edefine immo:rtality in strictly 1ogicail terms also influences his critique of pl'evious authoi's :and his own generail condusions. He picks u:p Fieino'.s notion that the human being is of an ambiguous nature, that is, part spirit 1and pa:rt oorpore1 al.5 This, of course, is new neither with Ficino nor with Pomponazzi, for the concept of a twofold nature goes hack at least as ia1· as Plwto. Plomponazzi',s use of 1this concept of a twofold nature, however, is unique. He casts the whole 2 In his book Renaissance Thought and Its Sources (New York: Columbia University Press, 1979), Paul Oskar Kristeller says, "Among the many problems and concepts that have occupied the thinkers of the past, and especially those of the Renaissance, the doctrine of immortality seems especially remote from the discussions and concerns of our time" (p. 181). He argues in this essay that, "The problem is still with us, and we may hope that it may yet lead to new answers that are more in accordance with our knowledge and our sensibilities than those transmitted to us by the thinkers of the past, especially those of the fifteenth and sixteenth centuries" (p. 196). s "Primum scilicet, quid, revelationibus et miraculis semotis, persistendoque pure infra limites naturales, hac in re sentis." Immortalitate, p. 36 (p. 281). All references to the Traatatus de immortalitate animae will appear in this form. The first page reference is to the Latin text and the page number in parentheses is to the English translation cited above. 4 "Alterum vero, quamnam sententiam Aristotelis in eadem materiam fuisse censes." Imrnortalitate, p. 36 (p. 281). 5 See Marsilius Ficino, " Five Questions Concerning the... (shrink)