First published in 1973, Sir Anthony Kenny’s classic introduction to Wittgenstein was widely praised for offering a lucid and historically informed account of the philosopher’s core concerns. Kenny's study is also remarkable for demonstrating the continuity between Wittgenstein’s early and late writings. Focusing on Wittgenstein’s philosophy of mind and language, Kenny closely examines the works of the middle years. He exposes apparent conflicts and then goes on to reconcile them, providing a persuasive argument for the unity of (...) Wittgenstein’s thought. This revised edition includes an extensive new introduction in which Kenny outlines developments in Wittgenstein scholarship since the book was first published and assesses Wittgenstein’s influence in the latter part of the twentieth century. (shrink)

We introduce a family of rules for adjusting one's credences in response to learning the credences of others. These rules have a number of desirable features. 1. They yield the posterior credences that would result from updating by standard Bayesian conditionalization on one's peers' reported credences if one's likelihood function takes a particular simple form. 2. In the simplest form, they are symmetric among the agents in the group. 3. They map neatly onto the familiar Condorcet voting results. 4. They (...) preserve shared agreement about independence in a wide range of cases. 5. They commute with conditionalization and with multiple peer updates. Importantly, these rules have a surprising property that we call synergy - peer testimony of credences can provide mutually supporting evidence raising an individual's credence higher than any peer's initial prior report. At first, this may seem to be a strike against them. We argue, however, that synergy is actually a desirable feature and the failure of other updating rules to yield synergy is a strike against them. (shrink)

Sir Anthony Kenny's engaging new multi-volume history of Western philosophy now advances into the modern era. The Rise of Modern Philosophy captures the fascinating story of the emergence, from the early sixteenth to the early nineteenth century, of the great ideas and intellectual systems that shaped modern thought. Kenny introduces us to some of the world's most original and influential thinkers and helps us gain an understanding of their famous works. The great minds we meet include Rene Descartes, (...) traditionally seen as the founder of modern philosophy; the great British philosophers Hobbes, Locke, and Hume; continental thinkers such as Spinoza, Liebniz, and Hegel; and the towering figure of Immanuel Kant, who perhaps more than any other made philosophy what it is today. Kenny first tells the story of modern philosophy chronologically: his lively, accessible narrative brings the philosophers to life and fills in the historical and intellectual background to their work. It is ideal as the first thing to read for someone new to this wonderfully creative period. Kenny then backtracks to look closely at each of the main areas of philosophical exploration in this period: knowledge and understanding; the nature of the physical universe; metaphysics (the most fundamental questions there are about existence); mind and soul; the nature and content of morality; political philosophy; and God. The book also features many intriguing and beautiful illustrations which evoke the human and social side of philosophy. Anyone who is interested in the evolution of modern thought will find this a book a treasure. (shrink)

Many philosophers have argued that "degree of belief" or "credence" is a more fundamental state grounding belief. Many other philosophers have been skeptical about the notion of "degree of belief", and take belief to be the only meaningful notion in the vicinity. This paper shows that one can take belief to be fundamental, and ground a notion of "degree of belief" in the patterns of belief, assuming that an agent has a collection of beliefs that isn't dominated by some other (...) collection in terms of the overall balance of truth and falsity that it could contain. (shrink)

According to proper functionalist theories of warrant, a belief is warranted only if it is formed by cognitive faculties that are properly functioning according to a good, truth-aimed design plan, one that is often thought to be specified either by intentional design or by natural selection. A formidable challenge to proper functionalist theories is the Swampman objection, according to which there are scenarios involving creatures who have warranted beliefs but whose cognitive faculties are not properly functioning, or are poorly designed, (...) or are not aimed at truth. In this paper, we draw lessons from cognitive science in order to develop a novel argument for the conclusion that the Swampman objection fails against proper functionalist theories of warrant. Our argument not only shows that the underlying, central intuition motivating Swampman-like scenarios is false but also motivates proper function as a necessary condition for warrant, thereby lending support to the claim that any theory of knowledge that lacks a proper function requirement is false. (shrink)

Cross-situational learning is a mechanism for learning the meaning of words across multiple exposures, despite exposure-by-exposure uncertainty as to the word's true meaning. We present experimental evidence showing that humans learn words effectively using cross-situational learning, even at high levels of referential uncertainty. Both overall success rates and the time taken to learn words are affected by the degree of referential uncertainty, with greater referential uncertainty leading to less reliable, slower learning. Words are also learned less successfully and more slowly (...) if they are presented interleaved with occurrences of other words, although this effect is relatively weak. We present additional analyses of participants’ trial-by-trial behavior showing that participants make use of various cross-situational learning strategies, depending on the difficulty of the word-learning task. When referential uncertainty is low, participants generally apply a rigorous eliminative approach to cross-situational learning. When referential uncertainty is high, or exposures to different words are interleaved, participants apply a frequentist approximation to this eliminative approach. We further suggest that these two ways of exploiting cross-situational information reside on a continuum of learning strategies, underpinned by a single simple associative learning mechanism. (shrink)

Zenon Pylyshyn argues that cognitively driven attentional effects do not amount to cognitive penetration of early vision because such effects occur either before or after early vision. Critics object that in fact such effects occur at all levels of perceptual processing. We argue that Pylyshyn’s claim is correct—but not for the reason he emphasizes. Even if his critics are correct that attentional effects are not external to early vision, these effects do not satisfy Pylyshyn’s requirements that the effects be direct (...) and exhibit semantic coherence. In addition, we distinguish our defense from those found in recent work by Raftopoulos and by Firestone and Scholl, argue that attention should not be assimilated to expectation, and discuss alternative characterizations of cognitive penetrability, advocating a kind of pluralism. (shrink)

Many philosophers have become worried about the use of standard real numbers for the probability function that represents an agent's credences. They point out that real numbers can't capture the distinction between certain extremely unlikely events and genuinely impossible ones—they are both represented by credence 0, which violates a principle known as “regularity.” Following Skyrms 1980 and Lewis 1980, they recommend that we should instead use a much richer set of numbers, called the “hyperreals.” This essay argues that this popular (...) view is the result of two mistakes. The first mistake, which this essay calls the “numerical fallacy,” is to assume that a distinction that isn't represented by different numbers isn't represented at all in a mathematical representation. In this case, the essay claims that although the real numbers do not make all relevant distinctions, the full mathematical structure of a probability function does. The second mistake is that the hyperreals make too many distinctions. They have a much more complex structure than credences in ordinary propositions can have, so they make distinctions that don't exist among credences. While they might be useful for generating certain mathematical models, they will not appear in a faithful mathematical representation of credences of ordinary propositions. (shrink)

Expected accuracy arguments have been used by several authors (Leitgeb and Pettigrew, and Greaves and Wallace) to support the diachronic principle of conditionalization, in updates where there are only finitely many possible propositions to learn. I show that these arguments can be extended to infinite cases, giving an argument not just for conditionalization but also for principles known as ‘conglomerability’ and ‘reflection’. This shows that the expected accuracy approach is stronger than has been realized. I also argue that we should (...) be careful to distinguish diachronic update principles from related synchronic principles for conditional probability. (shrink)

Anthony Kenny on his personal struggles with belief.

Smith gives an excellent overview on research in language evolution, in which he discusses several recent models of how linguistic systems and the cognitive capacities involved in language learning may have co‐evolved. He illustrates how combined pressures on language learning and communication/use produce compositionally structured languages. Once in place, a (culturally transmitted) communication system creates new selection pressures on the capacity for acquiring these systems.

Bayesianism is a collection of positions in several related fields, centered on the interpretation of probability as something like degree of belief, as contrasted with relative frequency, or objective chance. However, Bayesianism is far from a unified movement. Bayesians are divided about the nature of the probability functions they discuss; about the normative force of this probability function for ordinary and scientific reasoning and decision making; and about what relation (if any) holds between Bayesian and non-Bayesian concepts.

To the extent that we have reasons to avoid these “bad B -properties”, these arguments provide reasons not to have an incoherent credence function b — and perhaps even reasons to have a coherent one. But, note that these two traditional arguments for probabilism involve what might be called “pragmatic” reasons (not) to be (in)coherent. In the case of the Dutch Book argument, the “bad” property is pragmatically bad (to the extent that one values money). But, it is not clear (...) whether the DBA pinpoints any epistemic defect of incoherent agents. The same can be said for Representation Theorem arguments, since they involve the structure of an agent’s preferences. (shrink)

Bill D'Alessandro talks to Kenny Easwaran about fractal music, Zoom conferences, being a good referee, teaching in math and philosophy, the rationalist community and its relationship to academia, decision-theoretic pluralism, and the city of Manhattan, Kansas.

Naive versions of decision theory take probabilities and utilities as primitive and use expected value to give norms on rational decision. However, standard decision theory takes rational preference as primitive and uses it to construct probability and utility. This paper shows how to justify a version of the naive theory, by taking dominance as the most basic normatively required preference relation, and then extending it by various conditions under which agents should be indifferent between acts. The resulting theory can make (...) all the decisions of classical expected utility theory, plus more in cases where expected utilities are infinite or undefined. Although the theory requires similarly strong assumptions to classical expected utility theory, versions of the theory can be developed with slightly weaker assumptions, without having to prove a new representation theorem for the weaker theory. This alternate foundation is particularly useful if probability is prior to preference, as suggested by the recent program to base probabilism on accuracy and alethic considerations rather than pragmatic ones. (shrink)

In the first paper, I discussed the basic claims of Bayesianism (that degrees of belief are important, that they obey the axioms of probability theory, and that they are rationally updated by either standard or Jeffrey conditionalization) and the arguments that are often used to support them. In this paper, I will discuss some applications these ideas have had in confirmation theory, epistemol- ogy, and statistics, and criticisms of these applications.

In lieu of an abstract, here is a brief excerpt of the content:Philosophy and Rhetoric 36.4 (2003) 379-383 [Access article in PDF] Husserl at the Limits of Phenomenology: Including Texts by Edmund Husserl. Maurice Merleau-Ponty. Ed. Leonard Lawlor with Bettina Bergo. Trans. Leonard Lawlor. Evanston, IL: Northwestern University Press, 2002. Pp. 192. $19.95 pbk. The most striking characteristic of this volume is the manner that it presents layers of interpretation to the reader, particularly in that the writing is not intended (...) as a postmodern fête, and has limited value as a hermeneutic enterprise. Ultimately the book's true contribution is the seventy-nine pages devoted to the translation and printing of lecture notes used by [End Page 379] Merleau-Ponty in a class he gave at College de France, shortly before his death. However, the explanation of why this is so will have to be withheld until the end of this review.The course that Merleau-Ponty gave was organized around three essays published by Edmund Husserl. These essays are included in the volume reviewed here and must be briefly dealt with, as they are the core of whatever thinking occurs within and around this book. Interesting essays all, they deal with three longstanding issues of philosophical debate. The first essay challenges the classical notion of a transcendent ideal. Husserl attempts to show, through an examination of geometry, that an ideal is first called into existence when it is called into the realm of human experience, and he does this without ever resorting to the quality of detached being that Plato attributes to ideals. Then, in his second essay, Husserl attempts to defeat modernist cosmology, arguing, against Galileo, that the earth is a fixed point in the universe. Finally, his third essay hearkens back to Heraclitus and Parmenides, examining how human experience is able to extract a sense of atemporal quiddity in a world that is constantly falling into a past. A reader might be baffled that an intellectual could make such claims, but they are made from within the framework of phenomenology, and, within this paradigm as Husserl explains it, the claims he makes do not seem ridiculous at all. "The Origins of Geometry," "The Originary Ark, The Earth, Does Not Move," and "The World of the Living Present,"— these are the three essays that Merleau-Ponty forms his lecture course around. At sixty pages within this volume, they constitute one third of the text itself. For intellectual worth, I would say that these essays are the finest contribution in the text, but that claim is discounted because much of the essay material was already available in English translation. Nevertheless, it only makes sense to have it included in this volume in order to conveniently work back and forth between Merleau-Ponty's notes and Husserl's actual essays.However, that brings us to a significant problem within the text itself. If readers are like me, they will realize that it is often difficult to draw conclusions from the notes of others. Like secretarial shorthand, notes rely on a reader's ability to read both what has been written and what has been withheld in an expressive passage. There is no code that will allow us to recover what Merleau-Ponty recovered as he looked down on his podium at these notes and then raised his head to speak to his class. All that we have are the fragments, and they do not make a coherent argument, lacking both the clarity and the painstaking thoroughness that we find in books [End Page 380] such as The Phenomenology of Perception and The Visible and the Invisible. Certainly one cannot fault Merleau-Ponty for this—he did not write these notes for us, but for himself. His course might have been magnificent, even transcendent, but we will not know that from these fragments.I suppose it could be argued that the ambiguity inherent in such fragments liberates the text and opens it for some sort of radical hermeneutic exegesis; however, I sigh at the very thought of such an argument. Unless we intend to transform... (shrink)

In a series of papers, Don Fallis points out that although mathematicians are generally unwilling to accept merely probabilistic proofs, they do accept proofs that are incomplete, long and complicated, or partly carried out by computers. He argues that there are no epistemic grounds on which probabilistic proofs can be rejected while these other proofs are accepted. I defend the practice by presenting a property I call ‘transferability’, which probabilistic proofs lack and acceptable proofs have. I also consider what this (...) says about the similarities between mathematics and, on the one hand natural sciences, and on the other hand philosophy. (shrink)

Mental or computer simulation of cause and effect of certain behaviors is a recognized approach to changing one’s attitude or triggering an action. Meanwhile, psychology research results suggest that frequency of simulation may affect the corresponding persuasiveness. This paper argues that with always-on sensing and data-driven visualization technologies, interactive tangible systems can be designed to simulate hypothetical outcomes of real-life behaviors in everyday contexts, which repeatedly stimulate users’ imagination of behavioral consequences and thereby behavioral intentions. To investigate the effect, a (...) working prototype of Incingarette, including a smart ashtray in connection with a digital picture frame, was built. When the ashtray is used for smoking, the digital picture is incrementally covered by virtual dust. Field trials involved participants in five daily smoking sessions. Post-session surveys show increasingly stronger perceived causality between smoking and the simulated outcomes, increasingly more vivid mental imagery of consequences, and increasingly intense intention to reduce smoking. Results suggest that repeatedly presenting simulated outcomes cognitively linked to real-life behaviors can increase behavioral intentions. (shrink)

It is sometimes alleged that arguments that probability functions should be countably additive show too much, and that they motivate uncountable additivity as well. I show this is false by giving two naturally motivated arguments for countable additivity that do not motivate uncountable additivity.

Fine has shown that assigning any value to the Pasadena game is consistent with a certain standard set of axioms for decision theory. However, I suggest that it might be reasonable to believe that the value of an individual game is constrained by the long-run payout of repeated plays of the game. Although there is no value that repeated plays of the Pasadena game converges to in the standard strong sense, I show that there is a weaker sort of convergence (...) it exhibits, and use this to define a notion of ‘weak expectation’ that can give values to the Pasadena game and many others, though not to all games that fail to have a strong expectation in the standard sense. CiteULike Connotea Del.icio.us What's this? (shrink)

I defend a causal reductionist account of the nature of rates of change like velocity and acceleration. This account identifies velocity with the past derivative of position and acceleration with the future derivative of velocity. Unlike most reductionist accounts, it can preserve the role of velocity as a cause of future positions and acceleration as the effect of current forces. I show that this is possible only if all the fundamental laws are expressed by differential equations of the same order. (...) Consideration of the continuity of time explains why the differential equations are all second order. This explanation is not available on non-causal or non-reductionist accounts of rates of change. Finally, I argue that alleged counterexamples to the reductionist account involving physically impossible worlds are irrelevant to an analysis of the properties that play a causal role in the actual world. 1 Background2 Grounding3 Causation4 The Proposal5 Why No Third Derivatives?6 Why Any Derivatives?7 Counterexamples? (shrink)

To answer the question of whether mathematics needs new axioms, it seems necessary to say what role axioms actually play in mathematics. A first guess is that they are inherently obvious statements that are used to guarantee the truth of theorems proved from them. However, this may neither be possible nor necessary, and it doesn’t seem to fit the historical facts. Instead, I argue that the role of axioms is to systematize uncontroversial facts that mathematicians can accept from a wide (...) variety of philosophical positions. Once the axioms are generally accepted, mathematicians can expend their energies on proving theorems instead of arguing philosophy. Given this account of the role of axioms, I give four criteria that axioms must meet in order to be accepted. Penelope Maddy has proposed a similar view in Naturalism in Mathematics, but she suggests that the philosophical questions bracketed by adopting the axioms can in fact be ignored forever. I contend that these philosophical arguments are in fact important, and should ideally be resolved at some point, but I concede that their resolution is unlikely to affect the ordinary practice of mathematics. However, they may have effects in the margins of mathematics, including with regards to the controversial “large cardinal axioms” Maddy would like to support. (shrink)

Taking Joyce’s (1998; 2009) recent argument(s) for probabilism as our point of departure, we propose a new way of grounding formal, synchronic, epistemic coherence requirements for (opinionated) full belief. Our approach yields principled alternatives to deductive consistency, sheds new light on the preface and lottery paradoxes, and reveals novel conceptual connections between alethic and evidential epistemic norms.

Bayesians standardly claim that there is rational pressure for agents’ credences to cohere across time because they face bad (epistemic or practical) consequences if they fail to diachronically cohere. But as David Christensen has pointed out, groups of individual agents also face bad consequences if they fail to interpersonally cohere, and there is no general rational pressure for one agent's credences to cohere with another’s. So it seems that standard Bayesian arguments may prove too much. Here, we agree with Christensen (...) that there is no general rational pressure to diachronically cohere, but we argue that there are particular cases in which there is rational pressure to diachronically cohere, as well as particular cases in which interpersonal probabilistic coherence is rationally required. More generally, we suggest that Bayesian arguments for coherence apply whenever a collection (of agents or time slices) has a shared dimension of value and an ability to coordinate their actions in a range of cases relevant to that value. Typically, this shared value and ability to coordinate is very strong across the time slices of one human being, and very weak across different human beings, but there are special cases where these can switch—i.e., some groups of humans will have as much reason for their beliefs to cohere across a particular range of cases as the time slices of one human usually do, but some time slices of a human will have as much freedom to differ in their beliefs from the others as the members of a group usually do. (shrink)

This popular selection of Wittgenstein’s key writings has now been updated to include new material relevant to recent debates about the philosopher. Follows the evolution of Wittgenstein’s philosophical thought from the Tractatus Logico-Philosophicus through to the Philosophical Investigations. Excerpts are arranged by topic and introduce readers to all the central concerns of Wittgenstein’s philosophy. Now includes a new chapter on ‘Sense, Nonsense and Philosophy’ incorporating material relevant to recent debates about Wittgenstein.

Frankfurt gave an account of “bullshit” as a statement made without regard to truth or falsity. Austin argued that a large amount of language consists of speech acts aimed at goals other than truth or falsity. We don't want our account of bullshit to include all performatives. I develop a modification of Frankfurt's account that makes interesting and useful categorizations of various speech acts as bullshit or not and show that this account generalizes to many other kinds of act as (...) well. I show that this illuminates some of Graeber's classification of “bullshit jobs,” though it doesn't fully agree with it. (shrink)

In my () I argued that a central component of mathematical practice is that published proofs must be “transferable” — that is, they must be such that the author's reasons for believing the conclusion are shared directly with the reader, rather than requiring the reader to essentially rely on testimony. The goal of this paper is to explain this requirement of transferability in terms of a more general norm on defeat in mathematical reasoning that I will call “convertibility”. I begin (...) by discussing two types of epistemic defeat: “rebutting” and “undercutting”. I give examples of both of these kinds of defeat from the history of mathematics. I then argue that an important requirement in mathematics is that published proofs be detailed enough to allow the conversion of rebutting defeat into undercutting defeat. Finally, I show how this sort of convertibility explains the requirement of transferability, and contributes to the way mathematics develops by the pattern referred to by Lakatos () as “lemma incorporation”. (shrink)

Doxastic TheoriesThe application of formal tools to questions related to epistemology is of course not at all new. However, there has been a surge of interest in the field now known as “formal epistemology” over the past decade, with two annual conference series and an annual summer school at Carnegie Mellon University, in addition to many one-off events devoted to the field. A glance at the programs of these series illustrates the wide-ranging set of topics that have been grouped under (...) this name, ranging from rational choice theory and the foundations of statistics, to logics of knowledge and formal measures of coherence, with much more besides.In this paper I will ignore most of these topics, and just trace some parts of the history of two ideas about belief whose current interaction may lead to future progress. One idea is the idea of belief, disbelief, and suspension of judgment as a meaningful tripartite dis .. (shrink)

In three respects, ethics can be marked by the category of the ‘priceless’. Its key reference point, ‘human dignity’, was described by Kant as the exact opposite to what can be priced in equivalents. As an enterprise, ethics is ‘priceless’ as a commitment of the human spirit which goes beyond and against the attitude of success calculation. Yet, an understanding of ethics as unconditional recognition and the anticipatory, asymmetric, innovative praxis (Helmut Peukert) that expresses it have a cost. Where does (...) the motivation to forego, for example, ethically problematic therapies, originate? How can respect for what is priceless be sustained in the face of the relentless spread of market categories diagnosed, among others, by Jürgen Habermas and Paul Ricoeur, against which religions may raise a delaying veto? Only a Christology that can adequately conceptualise the experience of the graciousness and superabundance of God’s gift is able to support the increasingly counter-cultural conviction of something beyond our disposition. (shrink)

Ten new graduate speech pathologists recounted their experiences in managing workplace ethical dilemmas in semi-structured interviews. Their stories were analysed for elements that described the nature and management of the ethical dilemmas. Ethical reasoning themes were generated to reflect the participants’ approaches to managing these dilemmas. Finally, a conceptual model, the Dynamic Model of Ethical Reasoning, was developed. This model incorporates the elements of awareness, independent problem solving, supported problem solving, and decision and outcome evaluation. Features of the model demonstrate (...) the complexity of ethical reasoning and the challenges that new graduates encounter when managing ethical dilemmas. The results have implications for preparing new graduates to manage ethical dilemmas in the workplace. (shrink)

Newcomb-like problems are classified by the payoff table of their act-state pairs, and the causal structure that gives rise to the act-state correlation. Decision theories are classified by the one or more points of intervention whose causal role is taken to be relevant to rationality in various problems. Some decision theories suggest an inherent conflict between different notions of rationality that are all relevant. Some issues with causal modeling raise problems for decision theories in the contexts where Newcomb problems arise.

We agree that language adapts to the brain, but we note that language also has to adapt to brain-external constraints, such as those arising from properties of the cultural transmission medium. The hypothesis that Christiansen & Chater (C&C) raise in the target article not only has profound consequences for our understanding of language, but also for our understanding of the biological evolution of the language faculty.

The central aim of this paper is to argue that there is a meaningful sense in which a concept of rationality can apply to a city. The idea will be that a city is rational to the extent that the collective practices of its people enable diverse inhabitants to simultaneously live the kinds of life they are each trying to live. This has significant implications for the varieties of social practices that constitute being more or less rational. Some of these (...) implications may be welcome to a theorist that wants to identify collective rationality with a notion of justice, while others are unwelcome. There are some significant challenges to this use of the concept of rationality, but I claim that these challenges at the city level have parallels at the individual level, and may thus help deepen our understanding of rationality at all levels. (shrink)

Six essential genes located near the mouse albino locus have been identified as required during specific periods of development. Amongst these six, each is required either during the preimplantation stages of development, at specific times during gastrulation, within 12 hrs after birth or during juvenile development. These genes were identified as a result of extensive genetic complementation analysis using embryos homozygous for the albino deletions. Although, in principal, the associated developmental abnormalities could result from loss of multiple genes, the deletion (...) phenotype in one case is identical to that induced by chemical mutagenesis. These results indicate that the abnormalities observed in deletion homozygotes may result from single gene loss. The deletions have proven useful not only as genetic tools to localize the position of the genes, but also as molecular entry points to the regions containing these genes. The current methodology being used to isolate candidate genes from the albino region is also reviewed here. (shrink)

I consider the notions of logical probability, degree of belief, and objective chance, and argue that a different formalism for conditional probability is appropriate for each.

Pascal’s Wager holds that one has pragmatic reason to believe in God, since that course of action has infinite expected utility. The mixed strategy objection holds that one could just as well follow a course of action that has infinite expected utility but is unlikely to end with one believing in God. Monton (2011. Mixed strategies can’t evade Pascal’s Wager. Analysis 71: 642–45.) has argued that mixed strategies can’t evade Pascal’s Wager, while Robertson (2012. Some mixed strategies can evade Pascal’s (...) Wager: a reply to Monton. Analysis 72: 295–98.) has argued that Monton is mistaken. We show that Monton is correct, highlight the crucial assumptions that he relies on, and shed some light on the role of mixed strategies in decision theory. (shrink)

Elevations in brain stimulation reward (BSR) thresholds have been observed in rats undergoing nicotine withdrawal and have been proposed as a sensitive measure of the negative affective state associated with nicotine withdrawal. mGluR are presynaptic autoreceptors that decrease glutamate release when stimulated. The aim of this study was to examine the role of glutamate neurotransmission in nicotine dependence. The mGluR agonist LY314582 (2.5–7.5 mg/kg) precipitated nicotine withdrawal as measured by elevations in BSR thresholds in nicotine-treated rats but not in controls. (...) It was hypothesized that LY314582 precipitated nicotine withdrawal by decreasing glutamatergic tone at postsynaptic glutamate receptors. Therefore, the effects of MPEP (0.5–2 mg/kg), an mGluR antagonist, and MK-801 (0.01–1 mg/kg), an NMDA receptor antagonist, were examined. MPEP elevated BSR thresholds by an equal magnitude in control and nicotine-treated rats. At low doses, MK-801 (0.01–0.2 mg/kg) lowered BSR thresholds to a similar extent in control and nicotine-treated rats. At higher doses, MK-801 (0.25–1 mg/kg) disrupted performance in nicotine-treated and control rats. These data indicate that mGluR and NMDA receptors regulate BSR in opposite directions in non-dependent animals, and chronic nicotine treatment does not alter these effects. Most importantly, the data demonstrate that the mGluR is involved in nicotine dependence, but mGluR and NMDA receptors do not mediate mGluR actions in nicotine dependence. (shrink)