One response to the problem of logical omniscience in standard possible worlds models of belief is to extend the space of worlds so as to include impossible worlds. It is natural to think that essentially the same strategy can be applied to probabilistic models of partial belief, for which parallel problems also arise. In this paper, I note a difficulty with the inclusion of impossible worlds into probabilistic models. Under weak assumptions about the space of worlds, most of (...) the propositions which can be constructed from possible and impossible worlds are in an important sense inexpressible; leaving the probabilistic model committed to saying that agents in general have at least as many attitudes towards inexpressible propositions as they do towards expressible propositions. If it is reasonable to think that our attitudes are generally expressible, then a model with such commitments looks problematic. (shrink)

There are two ways of representing rational belief: qualitatively as yes-or-no belief, and quantitatively as degrees of belief. Standard rationality conditions are: consistency and logical closure, for qualitative belief, satisfaction of the probability axioms, for quantitative belief, and a relationship between qualitative and quantitative beliefs in accordance with the Lockean thesis. In this paper, it is shown that these conditions are inconsistent with each of three further rationality conditions: fallibilism, open-mindedness, and invariance under independent conceptual expansions. Restrictions of the (...) Lockean thesis that have been suggested in the literature cannot remove the inconsistency. In the outlook we discuss two alternative ways of dealing with this problem: restricting conjunctive closure or going for a dual system account. (shrink)

We present a theory of truth in fiction that improves on Lewis's [1978] ‘Analysis 2’ in two ways. First, we expand Lewis's possible worlds apparatus by adding non-normal or impossible worlds. Second, we model truth in fiction as belief revision via ideas from dynamic epistemic logic. We explain the major objections raised against Lewis's original view and show that our theory overcomes them.

A paradox of self-reference in beliefs in games is identified, which yields a game-theoretic impossibility theorem akin to Russell’s Paradox. An informal version of the paradox is that the following configuration of beliefs is impossible:Ann believes that Bob assumes that.

Epistemological accounts that make use of a safety condition on knowledge, historically, face serious problems regarding beliefs that are necessarily true. This is because necessary truths are true in all possible worlds, so such beliefs can be safe even when the bases for the beliefs are epistemically problematic. The existence of such problematically safe beliefs would undermine a major motivation for the condition itself: the ability to evaluate how well a belief tracks the truth. In this (...) paper, we’ll argue that incorporating impossible worlds into the evaluation of beliefs solves this problem, but only if the relevant account of impossible worlds entails that many impossible worlds are incredibly similar to the actual world. Further, we’ll argue that, as a result of including impossible worlds, some philosophical beliefs are unsafe, and many more are potentially unsafe. But, we argue, even if this is the case, we can still make philosophical progress. (shrink)

Peter G¨ ardenfors proved a theorem purporting to show that it is impossible to adjoin to the AGM -postulates for belief-revision a principle of monotonicity for revisions. The principle of monotonicity in question is implied by the Ramsey test for conditionals. So G¨.

In this paper, I develop an algorithmic impossible-worlds model of belief and knowledge that provides a middle ground between models that entail that everyone is logically omniscient and those that are compatible with even the most egregious kinds of logical incompetence. In outline, the model entails that an agent believes (knows) φ just in case she can easily (and correctly) compute that φ is true and thus has the capacity to make her actions depend on whether φ. The model (...) thereby captures the standard view that belief and knowledge ground are constitutively connected to dispositions to act. As I explain, the model improves upon standard algorithmic models developed by Parikh, Halpern, Moses, Vardi, and Duc, among other ways, by integrating them into an impossible-worlds framework. The model also avoids some important disadvantages of recent candidate middle-ground models based on dynamic epistemic logic or step logic, and it can subsume their most important advantages. (shrink)

In ‘The Turning Point in Philosophy’ Moritz Schlick expressed the following view: ‘Everything is knowable which can be expressed, and this is the total subject matter concerning which meaningful questions can be raised. There are consequently no questions which are in principle unanswerable, no problems which are in principle insoluble.’ I will refer to this as Schlick's principle, although it is shared by many others. What it amounts to is the view that all meaningful questions can be answered by rational (...) procedures, that is by logical argument or appeal to evidence. It is this view which I wish to challenge, at the same time relating what I have to say to belief in God. For it follows from Schlick's principle that provided the question ‘Does God exist?’ can be meaningfully asked, it is in principle possible to answer it either affirmatively or negatively. Having done so, we would then know, and not merely believe, that God does or does not exist. I will try to show that provided the question ‘Does God exist?’ can be meaningfully asked, no such consequence need be taken to follow. (shrink)

It is commonly assumed that if one's beliefs are epistemically rational, then those beliefs must at least be consistent with one another. I argue that this assumption is false. I argue that it can be epistemically rational for a person to believe an inconsistent set of statements. I argue further that while one can rationally believe an inconsistent set of statements, one cannot rationally believe a set of statements that she or he knows to be inconsistent. ;In opposition, (...) versions of the "Preface Paradox" and the "Lottery Paradox" seem to show that one can be epistemically rational in believing a set of statements that she or he knows is inconsistent. More specifically, these paradoxes seem to show that one can be epistemically rational in believing a set of statements of the form . ;I carefully examine both paradoxes and argue for solutions that preserve all of the epistemic principles that generate these paradoxes and the assumption that it is not rational to believe a set of statements that is known to be inconsistent. (shrink)

I review but don’t endorse Marcus’ arguments that impossible beliefs are impossible. I defend her claim that belief’s objects are, in some important sense, not the bearers of truth and falsity, discuss her disposition- alism about belief, and argue it’s a good fit with the idea that belief’s objects are Russellian states of affairs.

Agents are often assumed to have degrees of belief (“credences”) and also binary beliefs (“beliefs simpliciter”). How are these related to each other? A much-discussed answer asserts that it is rational to believe a proposition if and only if one has a high enough degree of belief in it. But this answer runs into the “lottery paradox”: the set of believed propositions may violate the key rationality conditions of consistency and deductive closure. In earlier work, we showed that (...) this problem generalizes: there exists no local function from degrees of belief to binary beliefs that satisfies some minimal conditions of rationality and non-triviality. “Locality” means that the binary belief in each proposition depends only on the degree of belief in that proposition, not on the degrees of belief in others. One might think that the impossibility can be avoided by dropping the assumption that binary beliefs are a function of degrees of belief. We prove that, even if we drop the “functionality” restriction, there still exists no local relation between degrees of belief and binary beliefs that satisfies some minimal conditions. Thus functionality is not the source of the impossibility; its source is the condition of locality. If there is any non-trivial relation between degrees of belief and binary beliefs at all, it must be a “holistic” one. We explore several concrete forms this “holistic” relation could take. (shrink)

This paper argues that modal realism has a problem with mathematical impossibilities. Due to the peculiar way it treats both propositions and mathematical objects, modal realism cannot distinguish the content of different mathematically impossible beliefs. While one might be happy to identify all logically impossible beliefs, there are many different mathematically impossible beliefs, none of which is a belief in a logical contradiction. The fact that it cannot distinguish these beliefs speaks against adopting (...) modal realism. (shrink)

This paper addresses how multiple individual credences on logically related issues should be aggregated into collective binary beliefs. We call this binarizing belief aggregation. It is vulnerable to dilemmas such as the discursive dilemma or the lottery paradox: proposition-wise independent aggregation can generate inconsistent or not deductively closed collective judgments. Addressing this challenge using the familiar axiomatic approach, we introduce general conditions on a binarizing belief aggregation rule, including rationality conditions on individual inputs and collective outputs, and determine which (...) rules (if any) satisfy different combinations of these conditions. Furthermore, we analyze similarities and differences between our proofs and other related proofs in the literature and conclude that the problem of binarizing belief aggregation is a free-standing aggregation problem not reducible to judgment aggregation or probabilistic opinion pooling. (shrink)

Impossible Worlds focuses on an exciting new theory in philosophy, with applications in metaphysics, logic, and the theory of meaning. Its central topic is: how do we meaningfully talk and reason about situations which, unbeknownst to us, are impossible? This issue emerges as a central problem in contemporary philosophical accounts of meaning, information, knowledge, belief, fiction, conditionality, and counterfactual supposition. The book is written bytwo of the leading philosophers in the area and contains original research of relevance to (...) professional philosophers and logicians working in metaphysics, philosophy of language, formal logic, and adjacentareas. (shrink)

Impossible worlds are representations of impossible things and impossible happenings. They earn their keep in a semantic or metaphysical theory if they do the right theoretical work for us. As it happens, a worlds-based account provides the best philosophical story about semantic content, knowledge and belief states, cognitive significance and cognitive information, and informative deductive reasoning. A worlds-based story may also provide the best semantics for counterfactuals. But to function well, all these accounts need use of (...) class='Hi'>impossible and as well as possible worlds. So what are impossible worlds? Graham Priest claims that any of the usual stories about possible worlds can be told about impossible worlds, too. But far from it. I'll argue that impossible worlds cannot be genuine worlds, of the kind proposed by Lewis, McDaniel or Yagisawa. Nor can they be ersatz worlds on the model proposed by Melia or Sider. Constructing impossible worlds, it turns out, requires novel metaphysical resources. (shrink)

We need to understand the impossible. Francesco Berto and Mark Jago start by considering what the concepts of meaning, information, knowledge, belief, fiction, conditionality, and counterfactual supposition have in common. They are all concepts which divide the world up more finely than logic does. Logically equivalent sentences may carry different meanings and information and may differ in how they're believed. Fictions can be inconsistent yet meaningful. We can suppose impossible things without collapsing into total incoherence. Yet for the (...) leading philosophical theories of meaning, these phenomena are an unfathomable mystery. To understand these concepts, we need a metaphysical, logical, and conceptual grasp of situations that could not possibly exist: Impossible Worlds. This book discusses the metaphysics of impossible worlds and applies the concept to a range of central topics and open issues in logic, semantics, and philosophy. It considers problems in the logic of knowledge, the meaning of alternative logics, models of imagination and mental simulation, the theory of information, truth in fiction, the meaning of conditional statements, and reasoning about the impossible. In all these cases, impossible worlds have an essential role to play. (shrink)

I want to model a finite, fallible cognitive agent who imagines that p in the sense of mentally representing a scenario—a configuration of objects and properties—correctly described by p. I propose to capture imagination, so understood, via variably strict world quantifiers, in a modal framework including both possible and so-called impossible worlds. The latter secure lack of classical logical closure for the relevant mental states, while the variability of strictness captures how the agent imports information from actuality in the (...) imagined non-actual scenarios. Imagination turns out to be highly hyperintensional, but not logically anarchic. Section 1 sets the stage and impossible worlds are quickly introduced in Sect. 2. Section 3 proposes to model imagination via variably strict world quantifiers. Section 4 introduces the formal semantics. Section 5 argues that imagination has a minimal mereological structure validating some logical inferences. Section 6 deals with how imagination under-determines the represented contents. Section 7 proposes additional constraints on the semantics, validating further inferences. Section 8 describes some welcome invalidities. Section 9 examines the effects of importing false beliefs into the imagined scenarios. Finally, Sect. 10 hints at possible developments of the theory in the direction of two-dimensional semantics. (shrink)

Mark Jago presents an original philosophical account of meaningful thought: in particular, how it is meaningful to think about things that are impossible. We think about impossible things all the time. We can think about alchemists trying to turn base metal to gold, and about unfortunate mathematicians trying to square the circle. We may ponder whether God exists; and philosophers frequently debate whether properties, numbers, sets, moral and aesthetic qualities, and qualia exist. In many philosophical or mathematical debates, (...) when one side of the argument gets things wrong, it necessarily gets them wrong. As we consider both sides of one of these philosophical arguments, we will at some point think about something that’s impossible. Yet most philosophical accounts of meaning and content hold that we can’t meaningfully think or reason about the impossible. -/- In The Impossible, Jago argues that we often gain new information, new beliefs, and, sometimes, fresh knowledge through logic, mathematics, and philosophy. That is why logic, mathematics, and philosophy are useful. We therefore require accounts of knowledge and belief, of information and content, and of meaning which allow space for the impossible. Jago’s aim in this book is to provide such accounts. He gives a detailed analysis of the concept of hyperintensionality, whereby logically equivalent contents may be distinct, and develops a theory in terms of possible and impossible worlds. Along the way, he provides a theory of what those worlds are and how they feature in our analysis of normative epistemic concepts: knowledge, belief, information, and content. (shrink)

“There is no use in trying,” said Alice; “one can’t believe impossible things.” “I dare say you haven’t had much practice,” said the Queen. “When I was your age, I always did it for half an hour a day. Why, sometimes I’ve believed as many as six impossible things before breakfast”. Lewis Carroll, Through the Looking Glass. -/- It is a rather common view among philosophers that one cannot, properly speaking, be said to believe, conceive, imagine, hope for, (...) or seek what is impossible. -/- Some philosophers, for instance George Berkeley and the early Wittgenstein, thought that logically contradictory propositions lack cognitive meaning (informational content) and cannot, therefore, be thought or believed. Philosophers who do not go as far as Berkeley and Wittgenstein in denying that impossible propositions or states of affairs are thinkable, may still claim that it is impossible to rationally believe an impossible proposition. On a classical “Cartesian” view of belief, belief is a purely mental state of the agent holding true a proposition p that she “grasps” and is directly acquainted with. But if the agent is directly acquainted with an impossible proposition, then, presumably, she must know that it is impossible. But surely no rational agent can hold true a proposition that she knows is impossible. Hence, no rational agent can believe an impossible proposition. Thus it seems that on the Cartesian view of propositional attitudes as inner mental states in which proposition are immediately apprehended by the mind, it is impossible for a rational agent to believe, imagine or conceive an impossible proposition. -/- Ruth Barcan Marcus (1983) has suggested that a belief attribution is defeated once it is discovered that the proposition, or state of affairs that is believed is impossible. According to her intuition, just as knowledge implies truth, belief implies possibility. -/- It is commonplace that people claim to believe propositions that later turn out to be impossible. According to Barcan Marcus, the correct thing to say in such a situation is not: I once believed that A but I don’t believe it any longer since I have come to realize that it is impossible that A. What one should say is instead: It once appeared to me that I believed that A, but I did not, since it is impossible that A. Thus, Barcan Marcus defends what we might call Alice’s thesis: Necessarily, for any proposition p and any subject x, if x believes p, then p is possible. -/- Alice’s thesis that it is impossible to hold impossible beliefs, seems to come into conflict with our ordinary practices of attributing beliefs. Consider a mathematical example. Some mathematicians believe that CH (the continuum hypothesis) is true and others believe that it is false. But if CH is true, then it is necessarily true; and if it is false, then it is necessarily false. Regardless of whether CH is true or false, the conclusion seems to be that there are mathematicians who believe impossible propositions. -/- Examples of apparent beliefs in impossible propositions outside of mathematics are also easy to come by. Consider, for example, Kripke’s (1999) story of the Frenchman Pierre who without realizing it has two different names ‘London’ and ‘Londres’ for the same city, London. After having arrived in London, Pierre may assent to ‘Londres is beautiful and London is not beautiful’ without being in any way irrational. It seems reasonably to infer from this that Pierre believes that Londres is beautiful and London is not beautiful. But since ‘Londres’ and ‘London’ are rigid designators for the same city, it seems to follow from this that Pierre believes the inconsistent proposition that we may express as ‘London is both beautiful and not beautiful’. (shrink)

“Mad belief” (in analogy with Lewisian “mad pain”) would be a belief state with none of the causal role characteristic of belief—a state not caused or apt to have been caused by any of the sorts of events that usually cause belief and involving no disposition toward the usual behavioral or other manifestations of belief. On token-functionalist views of belief, mad belief in this sense is conceptually impossible. Cases of delusion—or at least some cases of delusion—might be cases of (...) belief gone half-mad, cases in which enough of the functional role characteristic of belief is absent that the subject is in an “in-between” state regarding the delusive content, such that it is neither quite right to say the subject determinately believes the delusive content nor quite right to say that she determinately fails to believe that content. Although Bortolotti (2010) briefly mentions such “sliding scale” approaches to the relationship of delusion and belief, she dismisses such approaches on rather thin grounds and then later makes some remarks that seem consonant with sliding scale approaches. (shrink)

The fundamental question of the ethics of belief is "What ought one to believe?" According to the traditional view of evidentialism, the strength of one's beliefs should be proportionate to the evidence. Conventional ways of defending and challenging evidentialism rely on the idea that what one ought to believe is a matter of what it is rational, prudent, ethical, or personally fulfilling to believe. Common to all these approaches is that they look outside of belief itself to determine what (...) one ought to believe. In this book Jonathan Adler offers a strengthened version of evidentialism, arguing that the ethics of belief should be rooted in the concept of belief—that evidentialism is belief's own ethics. A key observation is that it is not merely that one ought not, but that one cannot, believe, for example, that the number of stars is even. The "cannot" represents a conceptual barrier, not just an inability. Therefore belief in defiance of one's evidence (or evidentialism) is impossible. Adler addresses such questions as irrational beliefs, reasonableness, control over beliefs, and whether justifying beliefs requires a foundation. Although he treats the ethics of belief as a central topic in epistemology, his ideas also bear on rationality, argument and pragmatics, philosophy of religion, ethics, and social cognitive psychology. (shrink)

It's often said that it is impossible to respond to non-evidential considerations in belief-formation, at least not directly and consciously. Many philosophers think that this provides grounds for accepting a normative thesis: typically, some kind of evidentialism about reasons for belief, or what one ought to believe. Some also think it supports thinking that evidentialist norms are constitutive of belief. There are a variety of ways in which one might try to support such theses by appeal to the impossibility-claim. (...) In this paper, I put pressure on these various attempts by raising a simple yet overlooked problem for them. In brief, the problem is that it isn't true that one cannot (directly and consciously) respond, in belief-formation to considerations that don't actually constitute (good) evidence for the proposition under consideration; what is true, at most, is that one cannot (directly and consciously) respond, in belief-formation to considerations that one oneself takes to be evidentially irrelevant to that proposition. While this point is obvious once stated, its significance hasn't been appreciated, or so I'll argue. Once we take full account of it, the standard arguments from the impossibility-claim to evidentialism don't go through. (shrink)

It is impossible to hold patently contradictory beliefs in mind together at once. Why? Because we know that it is impossible for both to be true. This impossibility is a species of rational necessity, a phenomenon that uniquely characterizes the relation between one person's beliefs. Here, Eric Marcus argues that the unity of the rational mind--what makes it one mind--is what explains why, given what we already believe, we can't believe certain things and must believe certain (...) others in this special sense. What explains this is that beliefs, and the inferences by which we acquire them, are constituted by a particular kind of endorsement of those very states and acts. This, in turn, entails that belief and inference are essentially self-conscious: to hold a belief or to make an inference is at the same time to know that one does. An examination of the nature of belief and inference, in light of the phenomenon of rational necessity, reveals how the unity of the rational mind is a function of our knowledge of ourselves as bound to believe the true. Rational self-consciousness is the form of mental togetherness. (shrink)

Epistemologists and philosophers of mind both ask questions about belief. Epistemologists ask normative questions about belief—which beliefs ought we to have? Philosophers of mind ask metaphysical questions about belief—what are beliefs, and what does it take to have them? While these issues might seem independent of one another, there is potential for an interesting sort of conflict: the epistemologist might think we ought to have beliefs that, according to the philosopher of mind, it is impossible to (...) have. This essay argues that this conflict does arise and that it creates problems for traditional skeptical views in epistemology. In particular, it argues that on certain popular views about the nature of belief, it is impossible to adopt the near-global agnosticism recommended by the skeptical epistemologist. On other plausible views, it is possible only in special circumstances, and this limitation undermines skeptical epistemological claims. The only views about the nature of belief on which there are no metaphysical hurdles to adopting the agnosticism recommended by the skeptic are views that face powerful objections—objections that are completely independent of antiskeptical epistemological considerations. (shrink)

An extraordinary, if circumscribed, positive shift has occurred since the mid-twentieth century in the perceived status of Hugh Everett III's 1956 theory of the universal wave function of quantum mechanics, now widely called the Many-Worlds Interpretation (MWI). Everett's starkly new interpretation denied the existence of a separate classical realm, contending that the experimental data can be seen as presenting a state vector for the whole universe. Since there is no state vector collapse, reality as a whole is strictly deterministic. Explained (...) jointly by the dynamical variables and the state vector, “this reality is not the reality we customarily think of, but is a reality composed of many worlds,” wrote Everett's colleague Bryce DeWitt. In this essay, I account briefly for the change of status in conventional scientific terms, yet chiefly in extended terms of three sets of ideas that I argue can be understood to affect believability in both scientific and religious contexts, illuminating helpfully the MWI phenomenon, and its engagement with theology: orthodoxy and heresy, language and reference, and faith and agnosticism. One's orientation relative to the variable content of these dynamic, socially oriented categories helps to make belief in ideas as metaphysically challenging as Everettian Quantum Mechanics, or particular ideas about God, either more or less believable. The categories will have the same function in a theology engaging Everett's theory, and in any theology at all written in a society deeply marked by what I further argue is a subtle, powerful, and pervasive mode of quasi-scientific thinking we can call societal constructive agnosticism, of which anyone doing theology today must be aware. (shrink)

Population axiology concerns how to evaluate populations in regard to their goodness, that is, how to order populations by the relations \is better than" and \is as good as". This eld has been riddled with para- doxes and impossibility results which seem to show that our considered beliefs are inconsistent in cases where the number of people and their welfare varies. All of these results have one thing in common, however. They all involve an adequacy condition that rules out (...) Derek Par t's Repugnant Conclusion. Moreover, some theorists have argued that we should accept the Repugnant Conclusion and hence that avoidance of this conclusion is not a convincing adequacy condition for a population axiology. As I shall show in this chapter, however, one can replace avoid- ance of the Repugnant Conclusion with a logically weaker and intuitively more convincing condition. The resulting theorem involves, to the best of my knowledge, logically weaker and intuitively more compelling con- ditions than the other theorems presented in the literature. As such, it challenges the very existence of a satisfactory population ethics. (shrink)

Population axiology concerns how to evaluate populations in regard to their goodness, that is, how to order populations by the relations “is better than ” and “is as good as”. This field has been riddled with paradoxes and impossibility results which seem to show that our considered beliefs are inconsistent in cases where the number of people and their welfare varies. All of these results have one thing in common, however. They all involve an adequacy condition that rules out (...) Derek Parfit’s Repugnant Conclusion. Moreover, some theorists have argued that we should accept the Repugnant Conclusion and hence that avoidance of this conclusion is not a convincing adequacy condition for a population axiology. As I shall show in this chapter, however, one can replace avoidance of the Repugnant Conclusion with a logically weaker and intuitively more convincing condition. The resulting theorem involves, to the best of my knowledge, logically weaker and intuitively more compelling conditions than the other theorems presented in the literature. As such, it. (shrink)

Modal knowledge accounts that are based on standards possible-worlds semantics face well-known problems when it comes to knowledge of necessities. Beliefs in necessities are trivially sensitive and safe and, therefore, trivially constitute knowledge according to these accounts. In this paper, I will first argue that existing solutions to this necessity problem, which accept standard possible-worlds semantics, are unsatisfactory. In order to solve the necessity problem, I will utilize an unorthodox account of counterfactuals, as proposed by Nolan, on which we (...) also consider impossible worlds. Nolan’s account for counterpossibles delivers the intuitively correct result for sensitivity i.e. S’s belief is sensitive in intuitive cases of knowledge of necessities and insensitive in intuitive cases of knowledge failure. However, we acquire the same plausible result for safety only if we reject his strangeness of impossibility condition and accept the modal closeness of impossible worlds. In this case, the necessity problem can be analogously solved for sensitivity and safety. For some, such non-moderate accounts might come at too high a cost. In this respect, sensitivity is better off than safety when it comes to knowing necessities. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy, Psychiatry, & Psychology 8.1 (2001) 33-37 [Access article in PDF] "Impossible Things before Breakfast":A Commentary on Burman and Richmond Gwen Adshead "Why sometimes, I've believed as many as six impossible things before breakfast." --Lewis Carroll, Through the Looking GlassBoth Burman and Richmond discuss how a feminist critique or take on a body of theory helps to illuminate or confuse further theoretical development. Burman applies such a (...) critique to False Memory Syndrome (FMS); Richmond to psychoanalytic accounts of eating disorders. In this commentary, I want to discuss the application of a feminist critique to two vital concepts for psychiatry: the recording and measurement of data, and truthful accounts of experience. These concepts are of course related, and I want to explore their connections, not only with each other, but with specific areas of mental health practice, namely, mental health research, psychodynamic psychotherapy, and expert psychiatric testimony. The Recording Angel: Subjectivity and Objectivity, Measurement and Truth Most feminist critiques of measurement begin with an attack on the traditional theoretical distinction between objective and subjective worlds (for example, Fox Keller 1985). Classical accounts of Western scientific practice have assumed that it is possible to divide external physical experience in this way, and this assumption generates two further beliefs: first, that it is possible for an observer to, as it were, stand apart or outside the events observed, and second, that objective accounts of events are somehow real-er or true-er than subjective accounts. This account contains some very old ideas about natural experience: first, that a fixed reality exists that is external to those who have experienced an event, and second, that this reality is observable by others, that is, there is a space between the observer and the observed. This notion of objectivity has been thought to be crucial to valid measurement.In contrast, a feminist critique counterargues that every observer is influenced and influences what he is studying; that he is himself "positioned" in the subject of his interest, in Rom Harré's term. Further, feminist theory argues that because the objective-subjective split is artificial, subjective accounts of experience may be just as "true" as objective accounts. Overarching is the notion that all social behavior is socially constructed and affected by social context, including "science" in all its forms.Such doubts about the exact nature of science have been fueled by two sets of theory within [End Page 33] "science"--the claims of quantum theory in the 1920s and Thomas Kuhn's account of shifting scientific paradigms in the 1960s--and both of these theories have been important for feminism and feminist critique of scientific practice. Despite many odd features, quantum theory has produced research with considerable explanatory power (Hawking 1988, Barrow 1991, Smollin 1997), and some of its claims provide indirect support for the feminist position described above. For example, one claim of quantum theory is that, at the micro-level of events, what is being observed is influenced by the position of the observer. If true, then the notion of an easy divide between internal and external space, in which observer and observed are separately located, is undermined; rather, every position taken by the observer influences the observed in a dynamic relationship. There is no objectivity but rather a developing matrix of positions that are not externally fixed, but changing and uncertain. Similarly, in relation to social construction of theory, Kuhn's description of the changing nature of scientific paradigms also emphasizes the importance of social and community influences on scientific theories and how "true" accounts of events can change. Internal and External Worlds: Implications for Mental Health Research and Psychotherapy Practice Arguably, feminist claims about the social positioning of science are now unremarkable; no one involved in research (especially mental health research) could dispute that what is studied, what is funded, and what is published is hugely influenced by many social and political processes. Even if only to a limited extent, quantum theory and Kuhn do support the doubt thrown on classic notions of objectivity by feminist theory; if only by suggesting that reality... (shrink)

If we receive information from multiple independent and partially reliable information sources, then whether we are justified to believe these information items is affected by how reliable the sources are, by how well the information coheres with our background beliefs and by how internally coherent the information is. We consider the following question. Is coherence a separable determinant of our degree of belief, i.e. is it the case that the more coherent the new information is, the more justified we (...) are in believing the new information, ceteris paribus? We show that if we consider sets of information items of any size (Holism), and if we assume that there exists a coherence Ordering over such sets and that coherence is a function of the probability distribution over the propositions in such sets (Probabilism), then Separability fails to hold. (shrink)

On the basis of impossibility results on probability, belief revision, and conditionals, it is argued that conditional beliefs differ from beliefs in conditionals qua mental states. Once this is established, it will be pointed out in what sense conditional beliefs are still conditional, even though they may lack conditional contents, and why it is permissible to still regard them as beliefs, although they are not beliefs in conditionals. Along the way, the main logical, dispositional, representational, (...) and normative properties of conditional beliefs are studied, and it is explained how the failure of not distinguishing conditional beliefs from beliefs in conditionals can lead philosophical and empirical theories astray. (shrink)

According to Niklas Luhmann, causality is both an impossibility and a necessity in education. On the one hand, the task of the teacher is an impossible one, because teaching as communication is a closed system that cannot determine the learning of pupils' psychical system in any causal sense. On the other hand, one cannot practice as a teacher without a belief in causality, i.e., in a causal connection between teaching and learning. In his article “The Child as the Medium (...) of Education,” Luhmann focuses on the enablement of education, despite its impossibility. His answer is that one thing that makes education possible is the emergence of the symbolically generalized medium “the child.” In this article, Lars Qvortrup focuses on Luhmann's understanding of causality. According to Luhmann, causality is not a simple, ontological fact, but the result of the attribution of certain causes to certain effects. The conclusion is that causality as an attribution category — and not causality as an ontological fact — is another thing that makes education possible. Qvortrup also concludes, however, that Luhmann is not alone in criticizing the traditional, mechanical concept of causality. Other contemporary philosophers and sociologists have pointed out that in order to analyze causality in complex social systems, one has to select some causal factors and ignore others. While others do this based on seemingly pure scientific and statistical criteria, Luhmann focuses on attribution as a social construction of causality. (shrink)

Belief has a special connection to truth, a connection not shared by mental states like imagination. One way of capturing this connection is by the claim that belief aims at truth. Normativists argue that we should understand this claim as a normative claim about belief – beliefs ought to be true. A second important connection between belief and truth is revealed by the transparency of belief, i.e. the fact that, when I deliberate about what to believe, I can settle (...) this deliberation only by appeal to considerations I take to show p to be true. It is natural to think that there is a connection between these two features of belief, that the fact that believing for non-evidential considerations would be irrational can help to explain why it is impossible, and Shah and Velleman make exactly this argument. However, as I shall argue, we cannot explain transparency on the basis of a normative requirement on belief. For this explanation to work non-evidential considerations would have to fail to be reasons for belief, and we would have to be able to explain why we are unable to form beliefs on the basis of non-evidential considerations by appealing to the fact that they fail to be reasons for belief. However, while it is plausible that non-evidential considerations are not in fact reasons for belief, the explanatory picture is the other way around. Such considerations only fail to be reasons for belief because we are unable to form beliefs on their basis. (shrink)

In this paper, I argue for a particular conception of impossible worlds. Possible worlds, as traditionally understood, can be used in the analysis of propositions, the content of belief, the truth of counterfactuals, and so on. Yet possible worlds are not capable of differentiating propositions that are necessarily equivalent, making sense of the beliefs of agents who are not ideally rational, or giving truth values to counterfactuals with necessarily false antecedents. The addition of impossible worlds addresses these (...) issues. The kinds of impossible worlds capable of performing this task are not mysterious sui generis entities, but sets of structured propositions that are themselves constructed out of possible worlds and relations. I also respond to a worry that these impossible worlds are unable to represent claims about the shape of modal space itself. (shrink)

Mental content and the problem of De Se belief -- Cognitive attitudes and content -- The doctrine of propositions -- The problem of De Se belief -- The property theory of content -- In favor of the property theory -- Perry's messy shopper and the argument from explanation -- Lewis's case of the two Gods -- Arguments from internalism and physicalism -- An inference to the best explanation -- Alternatives to the property theory -- The triadic view of belief -- (...) How the property theory and the triadic view are rivals -- Dyadic propositionalism reconsidered -- Arguments against the property theory -- Self-ascription and self-awareness -- Nonexistence and impossible contents -- Stalnaker's argument -- Propositionalist arguments from inference -- The property theory and De Re belief -- Lewis's account of De Re belief -- McKay's objection to Lewis -- Mistaken identity and the case of the shy secret admirer -- Some other worries and concluding remarks -- The property theory, rationality, and Kripke's puzzle about belief -- Kripke's puzzle about belief -- The puzzle argument -- A solution to the puzzle -- Puzzles with empty names and kind terms -- The property theory, twin earth, and belief about kinds -- Twin earth and two kinds of internalism -- The twin earth argument -- An internalist response (stage one) -- An internalist response (stage two) -- Self-ascription and belief about kinds. (shrink)

Population axiology concerns how to evaluate populations in regard to their goodness, that is, how to order populations by the relations “is better than” and “is as good as”. This field has been riddled with impossibility results which seem to show that our considered beliefs are inconsistent in cases where the number of people and their welfare varies.1 All of these results have one thing in common, however. They all involve an adequacy condition that rules out Derek Parfit’s Repugnant (...) Conclusion: The Repugnant Conclusion: For any perfectly equal population with very high positive welfare, there is a population with very low positive welfare which is better, other things being equal.2 1 The informal Mere Addition Paradox in Parfit (1984), pp. 419ff is the locus classicus. For an informal proof of a similar result with stronger assumptions, see Ng (1989), p. 240. A formal proof with slightly stronger assumptions than Ng’s can be found in Blackorby and Donaldson (1991). For theorems with much weaker assumptions, see my (1999), (2000b), and especially (2000a), (2001), and (2009). 2 See Parfit (1984), p. 388. My formulation is more general than Parfit’s apart from that he doesn’t demand that the people with very high welfare are equally well off. Expressions such as “a population with very high positive welfare”, “a population with very low positive welfare”, etc., are elliptical for the more cumbersome phrases “a population consisting only of lives with.. (shrink)

I present a possible worlds semantics for a hyperintensional belief revision operator, which reduces the logical idealization of cognitive agents affecting similar operators in doxastic and epistemic logics, as well as in standard AGM belief revision theory. (Revised) belief states are not closed under classical logical consequence; revising by inconsistent information does not perforce lead to trivialization; and revision can be subject to ‘framing effects’: logically or necessarily equivalent contents can lead to different revisions. Such results are obtained without resorting (...) to non-classical logics, or to non-normal or impossible worlds semantics. The framework combines, instead, a standard semantics for propositional S5 with a simple mereology of contents. (shrink)

This essay discusses the difficulty to reconcile two paradigms about beliefs: the binary or categorical paradigm of yes/no beliefs and the probabilistic paradigm of degrees of belief. The possibility for someone to hold both types of belief simultaneously is challenged by the lottery paradox, and more recently by a general impossibility theorem by Dietrich and List (2018, 2021). The nature, relevance, and implications of the tension are explained and assessed.

Inspired by the work of Wilfrid Sellars, Michael Williams launches an all-out attack on what he calls "phenomenalism," the idea that our knowledge of the world rests on a perceptual or experiential foundation. The point of this wider-than-normal usage of the term "phenomenalism," according to which even some forms of direct realism deserve to be called phenomenalistic, is to call attention to important continuities of thought between theories often thought to be competitors. Williams's target is not phenomenalism in its classical (...) sense-datum and reductionist form but empiricism generally. Williams examines and rejects the idea that, unless our beliefs are answerable to a "given" element in experience, objective knowledge will be impossible. Groundless Belief was first published in 1977. This second edition contains a new afterword in which Williams places his arguments in the context of some current discussions of coherentism versus the Myth of the Given and explains their relation to subsequent developments in his own epistemological views. (shrink)

It is now well known that, on pain of triviality, the probability of a conditional cannot be identified with the corresponding conditional probability [25]. This surprising impossibility result has a qualitative counterpart. In fact, Peter Gärdenfors showed in [13] that believing ‘If A then B’ cannot be equated with the act of believing B on the supposition that A — as long as supposing obeys minimal Bayesian constraints. Recent work has shown that in spite of these negative results, the question (...) ‘how to accept a conditional?’ has a clear answer. Even if conditionals are not truth-carriers, they do have precise acceptability conditions. Nevertheless most epistemic models of conditionals do not provide acceptance conditions for iterated conditionals. One of the main goals of this essay is to provide a comprehensive account of the notion of epistemic conditionality covering all forms of iteration. First we propose an account of the basic idea of epistemic conditionality, by studying the conditionals validated by epistemic models where iteration is permitted but not constrained by special axioms. Our modeling does not presuppose that epistemic states should be represented by belief sets (we only assume that to each epistemic state corresponds an associated belief state). A full encoding of the basic epistemic conditionals (encompassing all forms of iteration) is presented and a representation result is proved. In the second part of the essay we argue that the notion of change involved in the evaluation of conditionals is suppositional, and that such notion should be distinguished from the notion of updating (modelled by AGM and other methods). We conclude by considering how some of the recent modellings of iterated change fare as methods for iterated supposing. (shrink)

What is the relationship between degrees of belief and binary beliefs? Can the latter be expressed as a function of the former—a so-called “belief-binarization rule”—without running into difficulties such as the lottery paradox? We show that this problem can be usefully analyzed from the perspective of judgment-aggregation theory. Although some formal similarities between belief binarization and judgment aggregation have been noted before, the connection between the two problems has not yet been studied in full generality. In this paper, we (...) seek to fill this gap. The paper is organized around a baseline impossibility theorem, which we use to map out the space of possible solutions to the belief-binarization problem. Our theorem shows that, except in limiting cases, there exists no belief-binarization rule satisfying four initially plausible desiderata. Surprisingly, this result is a direct corollary of the judgment-aggregation variant of Arrow’s classic impossibility theorem in social choice theory. (shrink)

Akratic belief, or belief one believes one should not have, has often been thought to be impossible. I argue that the possibility of akratic belief should be accepted as a pre-theoretical datum. I distinguish intuitive, defensive, systematic, and diagnostic ways of arguing for this view, and offer an argument that combines them. After offering intuitive examples of akratic belief, I defend those examples against a common argument against the possibility of akratic belief, which I call the Nullification Argument. I (...) then offer an Argument from Belief Attribution, using a discussion of the marks by which we typically attribute belief to defend attributions of akratic belief. I conclude by offering a way to explain what is puzzling about akratic belief, while allowing that it is possible. (shrink)

In recent years Russell´s view that there are singular propositions, namely propositions that contain the individuals they are about, has gained followers. As a response to a number of puzzles about attitude ascriptions several Russellians (as I will call those who accept the view that proper names and indexicals only contribute their referents to the propositions expressed by the sentences in which they occur), including David Kaplan and Nathan Salmon, have drawn a distinction between what proposition is believed and how (...) it is believed.1 While it is generally agreed upon among Russellians that this distinction needs to be drawn there is considerable disagreement as to what exactly the distinction amounts to and what role the what and the how should play. The most plausible option seems to be to not assign a semantic value to the cognitive role played by the name or indexical in the sentence assented to. But recently Mark Richard2 has attempted to make the cognitive role affect truth values by building it into the truth conditions of belief reports.3 I will argue that Richard’s attempt fails to satisfy our pretheoretical intuitions about the sharing of beliefs. Furthermore, and more surprisingly, I will argue that Richard’s theory makes it virtually impossible for us to judge whether or not most belief reports are true or false, since doing so would involve what I call RAM probing, which would require viewing elements that are essentially private. (shrink)

Inspired by the work of Wilfrid Sellars, Michael Williams launches an all-out attack on what he calls "phenomenalism," the idea that our knowledge of the world rests on a perceptual or experiential foundation. The point of this wider-than-normal usage of the term "phenomenalism," according to which even some forms of direct realism deserve to be called phenomenalistic, is to call attention to important continuities of thought between theories often thought to be competitors. Williams's target is not phenomenalism in its classical (...) sense-datum and reductionist form but empiricism generally. Williams examines and rejects the idea that, unless our beliefs are answerable to a "given" element in experience, objective knowledge will be impossible. Groundless Belief was first published in 1977. This second edition contains a new afterword in which Williams places his arguments in the context of some current discussions of coherentism versus the Myth of the Given and explains their relation to subsequent developments in his own epistemological views. (shrink)

In this paper, I defend the view that truth is a constitutive norm of belief formation, argue in favour of a virtue-theoretic account of epistemic evaluation and respond to possible objections. In §1, I argue that belief necessarily aims at truth. In §2, I defend a virtue-theoretic approach to epistemic evaluation in response to concerns about epistemic luck and doxastic control. In §3, I distinguish between evaluative and deontic norms in order to avoid the charge that we are subject to (...) impossible epistemic demands. In §4, I study the relationship between epistemic norms, practical interests and ascriptions of knowledge. (shrink)

It is shown that the axioms Cubitt and Sugden (1994; Economic J. 104: 798) impose on a theory of rationally justifiable play (TRJP) do not prevent the possibility that two players necessarily disagree concerning the probability they ascribe to the choice of a third player. This appears to indicate that those axioms are not sufficient for defining a `reasonable' TRJP. In addition, for the case in which a player's beliefs are statistically independent, conditions for a TRJP are suggested under (...) which the existence of a quasi-strict equilibrium is sufficient, but the existence of a consistent n-pair is not, for defining a TRJP meeting those requirements. (shrink)

We must change our beliefs, and change them in particular ways, in response to new information. But not all changes are created equal: some are rational changes, some not. The Problem of Epistemic Change is the problem of specifying the rational constraints on how the epistemic state of an agent ought to change in the face of new information. This dissertation is about the philosophical and logical investigation of rational belief change. I start by arguing that the familiar foundations---coherence (...) distinction from static epistemology does not adequately carve up the logical space of theories of epistemic change. It is better to think of theories as being loosely ordered along a continuum from more to less foundational. The ordering, however, is "clumpy" in the sense that there are large regions in the ordering which remain unexplored. I then present and develop GDEC which is a new foundations model of belief revision that fills a gap in this ordering of theories of epistemic change. The key insight in GDEC is that belief that...is ambiguous between the attitudes of accept that...and expect that... GDEC respects the difference and how it matters for epistemic change. I show that GDEC is a genuine competitor to the AGM theory of belief revision in the sense that the two approaches are incompatible. The remainder of the dissertation is devoted to exploring the logical dynamics of GDEC and the models I develop here which extend it by applying them to a series of richer epistemic environments. I show how puzzles and paradoxes which confound other theories of belief revision are solved in a unified way by GDEC and its extensions. In particular, I give solutions to Moore's Paradox, Fuhrmann's Impossibility Theorem, the Reduction Problem of Epistemic Conditionals, and the Gardenfors Impossibility Theorem. (shrink)