The present volume collects some of Barwise's papers written since then, those directly concerned with relations among logic, situation theory, and situation semantics. Several papers appear here for the first time.

Presents a mathematically rigorous, philosophically sound foundation for a science of information.

Is it true that if zombies---creatures who are behaviorally indistinguishable from us, but no more conscious than a rock-are logically possible, the computational conception of mind is false? Are zombies logically possible? Are they physically possible? This paper is a careful, sustained argument for affirmative answers to these three questions.

Reasoning About Knowledge is the first book to provide a general discussion of approaches to reasoning about knowledge and its applications to distributed ...

A Theory of Truth and Semantic Representation Hans Kamp. INTRODUCTION Two conceptions of meaning have dominated formal semantics of natural language. ...

Copyright © 2010–2015 All rights reserved. Jonathan Bennett [Brackets] enclose editorial explanations. Small ·dots· enclose material that has been added, but can be read as though it were part of the original text. Occasional •bullets, and also indenting of passages that are not quotations, are meant as aids to grasping the structure of a sentence or a thought. Every four-point ellipsis . . . . indicates the omission of a brief passage that seems to present more difficulty than it is (...) worth. (shrink)

I urge return by the lights of logic and commonsense to a dialectical tabula rasa – according to which: (1) consciousness, in the ordinary pre-analytic sense of the term, is identified with P-consciousness, and “A-consciousness” is supplanted by suitably configured terms from its Blockian definition; (2) the supposedly fallacious Searlean argument for the view that a function of P-consciousness is to allow flexible and creative cognition is enthymematic and, when charitably specified, quite formidable.

Artificial agents (AAs), particularly but not only those in Cyberspace, extend the class of entities that can be involved in moral situations. For they can be conceived of as moral patients (as entities that can be acted upon for good or evil) and also as moral agents (as entities that can perform actions, again for good or evil). In this paper, we clarify the concept of agent and go on to separate the concerns of morality and responsibility of agents (most (...) interestingly for us, of AAs). We conclude that there is substantial and important scope, particularly in Computer Ethics, for the concept of moral agent not necessarily exhibiting free will, mental states or responsibility. This complements the more traditional approach, common at least since Montaigne and Descartes, which considers whether or not (artificial) agents have mental states, feelings, emotions and so on. By focussing directly on mind-less morality we are able to avoid that question and also many of the concerns of Artificial Intelligence. A vital component in our approach is the Method of Abstraction for analysing the level of abstraction (LoA) at which an agent is considered to act. The LoA is determined by the way in which one chooses to describe, analyse and discuss a system and its context. The Method of Abstraction is explained in terms of an interface or set of features or observables at a given LoA. Agenthood, and in particular moral agenthood, depends on a LoA. Our guidelines for agenthood are: interactivity (response to stimulus by change of state), autonomy (ability to change state without stimulus) and adaptability (ability to change the transition rules by which state is changed) at a given LoA. Morality may be thought of as a threshold defined on the observables in the interface determining the LoA under consideration. An agent is morally good if its actions all respect that threshold; and it is morally evil if some action violates it. That view is particularly informative when the agent constitutes a software or digital system, and the observables are numerical. Finally we review the consequences for Computer Ethics of our approach. In conclusion, this approach facilitates the discussion of the morality of agents not only in Cyberspace but also in the biosphere, where animals can be considered moral agents without their having to display free will, emotions or mental states, and in social contexts, where systems like organizations can play the role of moral agents. The primary cost of this facility is the extension of the class of agents and moral agents to embrace AAs. (shrink)

I propose to consider the question, "Can machines think?" This should begin with definitions of the meaning of the terms "machine" and "think." The definitions might be framed so as to reflect so far as possible the normal use of the words, but this attitude is dangerous, If the meaning of the words "machine" and "think" are to be found by examining how they are commonly used it is difficult to escape the conclusion that the meaning and the answer to (...) the question, "Can machines think?" is to be sought in a statistical survey such as a Gallup poll. But this is absurd. Instead of attempting such a definition I shall replace the question by another, which is closely related to it and is expressed in relatively unambiguous words. The new form of the problem can be described in terms of a game which we call the 'imitation game." It is played with three people, a man (A), a woman (B), and an interrogator (C) who may be of either sex. The interrogator stays in a room apart front the other two. The object of the game for the interrogator is to determine which of the other two is the man and which is the woman. He knows them by labels X and Y, and at the end of the game he says either "X is A and Y is B" or "X is B and Y is A." The interrogator is allowed to put questions to A and B. We now ask the question, "What will happen when a machine takes the part of A in this game?" Will the interrogator decide wrongly as often when the game is played like this as he does when the game is played between a man and a woman? These questions replace our original, "Can machines think?". (shrink)

Consciousness is a mongrel concept: there are a number of very different "consciousnesses." Phenomenal consciousness is experience; the phenomenally conscious aspect of a state is what it is like to be in that state. The mark of access-consciousness, by contrast, is availability for use in reasoning and rationally guiding speech and action. These concepts are often partly or totally conflated, with bad results. This target article uses as an example a form of reasoning about a function of "consciousness" based on (...) the phenomenon of blindsight. Some information about stimuli in the blind field is represented in the brains of blindsight patients, as shown by their correct "guesses," but they cannot harness this information in the service of action, and this is said to show that a function of phenomenal consciousness is somehow to enable information represented in the brain to guide action. But stimuli in the blind field are BOTH access-unconscious and phenomenally unconscious. The fallacy is: an obvious function of the machinery of access-consciousness is illicitly transferred to phenomenal consciousness. (shrink)

When a mental state is conscious – in the sense that there is something it is like for the subject to have it – it instantiates a certain property F in virtue of which it is a conscious state. It is customary to suppose that F is the property of having sensory quality. The paper argues that this supposition is false. The first part of the paper discusses reasons for thinking that unconscious mental states can have a sensory quality, for (...) example in cases of absent-minded perception. If unconscious mental states can have a sensory quality, then sensory quality is an insufficient condition for consciousness. The second part of the paper argues that there are even better reasons to think that sensory quality is an unnecessary condition for consciousness. The idea is that mental states can be conscious even when they lack sensory quality, for example, in the case of certain conscious propositional attitudes. In the third part of the paper, an alternative to the rejected supposition, drawn from the phenomenological tradition, is offered: that consciousness is a matter of implicit self-awareness, rather than of sensory quality. According to this alternative, a mental state is conscious when, and only when, it involves implicit self-awareness. (shrink)

The title of The Rediscovery of the Mind suggests the question "When was the mind lost?" Since most people may not be aware that it ever was lost, we must also then ask "Who lost it?" It was lost, of course, only by philosophers, by certain philosophers. This passed unnoticed by society at large. The "rediscovery" is also likely to pass unnoticed. But has the mind been rediscovered by the same philosophers who "lost" it? Probably not. John Searle is an (...) analytic philosopher, with some of the same notions as the positivists and behaviorists who rejected consciousness and "lost" the mind in the first place, but he also does not sound like the kind of reductionist who would have joined that crowd. His views, indeed, are sensible enough, and some of his insights so important, that it is a shame to find his thought profoundly limited by some of the same mistakes and prejudices that ruined philosophy, and not just philosophy of mind, under the influence of those positivists and behaviorists. There is enough of genuine value in his treatment, that it can easily be taken up and, with relatively slight modification, added to what is of permanent value in the history of philosophy. (shrink)

The problem of `conscious inessentialism' is examined in the literature, and an argument is presented that the presence of consciousness is indeed marked by a behavioural difference, but that this should be looked for at the cultural level of speech communities.

Bringing together powerful new tools from set theory and the philosophy of language, this book proposes a solution to one of the few unresolved paradoxes from antiquity, the Paradox of the Liar. Treating truth as a property of propositions, not sentences, the authors model two distinct conceptions of propositions: one based on the standard notion used by Bertrand Russell, among others, and the other based on J.L. Austin's work on truth. Comparing these two accounts, the authors show that while the (...) Russellian conception of the relation between sentences, propositions, and truth is crucially flawed in limiting cases, the Austinian perspective has fruitful applications to the analysis of semantic paradox. In the course of their study of a language admitting circular reference and containing its own truth predicate, Barwise and Etchemendy also develop a wide range of model-theoretic techniques--based on a new set-theoretic tool, Peter Aczel's theory of hypersets--that open up new avenues in logical and formal semantics. (shrink)

‘[I]ntrospection’ is just a convenient word to describe our way of knowing what is going on in our own mind, and anyone convinced that we know—at least sometimes—what is going on in our own mind and therefore, that we have a mind and, therefore, that we are not zombies, must believe that introspection is the answer we are looking for. I, too, believe in introspection.

In recent philosophy of mind, it is often assumed that consciousness and self-consciousness are two separate phenomena. In this paper, I argue that this is not quite right. The argument proceeds in two phases. First, I draw a distinction between (i) being self-conscious of a thought that p and (ii) self-consciously thinking that p. I call the former transitive self-consciousness and the latter intransitive self-consciousness. I then argue that consciousness does depend on intransitive self-consciousness, and that the common reasons for (...) denying the dependence of consciousness upon self-consciousness apply only to transitive self-consciousness. (shrink)

This paper distinguishes and interrelates a number of respects in which persons have been thought to be in a specially favorable epistemic position vis-A-Vis their own mental states. The most important distinction is a six-Fold one between infallibility, Omniscience, Indubitability, Incorrigibility, Truth-Sufficiency, And self-Warrant. Each of these varieties can then be sub-Divided as the kind of modality, If any, Involved. It is also argued that discussions of self-Knowledge have been hampered by a failure to recognize these distinctions.

Can knowledge provide its own justification? This sceptical challenge - known as the problem of the criterion - is one of the major issues in the history of epistemology, and this volume provides its first comprehensive study, in a span of time that goes from Sextus Empiricus to Quine. After an essential introduction to the notions of knowledge and of philosophy of knowledge, the book provides a detailed reconstruction of the history of the problem. There follows a conceptual analysis of (...) its logical features, and a comparative examination of a phenomenology of solutions that have been suggested in the course of the history of philosophy in order to overcome it, from Descartes to Popper. In this context, an indirect approach to the problem of the criterion is defended as the most successful strategy against the sceptical challenge. (shrink)