We explore the question of whether sustained rational disagreement is possible from a broadly Bayesian perspective. The setting is one where agents update on the same information, with special consideration being given to the case of uncertain information. The classical merging of opinions theorem of Blackwell and Dubins shows when updated beliefs come and stay closer for Bayesian conditioning. We extend this result to a type of Jeffrey conditioning where agents update on evidence that is uncertain but solid. However, merging (...) of beliefs does not generally hold for Jeffrey conditioning on evidence that is fluid. Several theorems on the asymptotic behavior of subjective probabilities are proven. Taken together they show that while a consensus nearly always emerges in important special cases, sustained rational disagreement can be expected in many other situations. (shrink)

This book is an extensive survey and critical examination of the literature on the use of expert opinion in scientific inquiry and policy making. The elicitation, representation, and use of expert opinion is increasingly important for two reasons: advancing technology leads to more and more complex decision problems, and technologists are turning in greater numbers to "expert systems" and other similar artifacts of artificial intelligence. Cooke here considers how expert opinion is being used today, how an expert's (...) uncertainty is or should be represented, how people do or should reason with uncertainty, how the quality and usefulness of expert opinion can be assessed, and how the views of several experts might be combined. He argues for the importance of developing practical models with a transparent mathematic foundation for the use of expert opinion in science, and presents three tested models, termed "classical," "Bayesian," and "psychological scaling." Detailed case studies illustrate how they can be applied to a diversity of real problems in engineering and planning. (shrink)

Scholarly interest in Margaret Cavendish's philosophical views has steadily increased over the past decade, but her epistemology has received little attention, and no consensus has emerged; Cavendish has been characterized as a skeptic, as a rationalist, as presenting an alternative epistemology to both rationalism and empiricism, and even as presenting no clear theory of knowledge at all. This paper concludes that Cavendish was only a modest skeptic, for she believed that humans can achieve knowledge through sensitive and rational perception as (...) well as through self-knowledge and can form probable opinions through reasoning. (shrink)

Recognizing that probability (the Greek doxa) was understood in pre-modern theories as the polar opposite of certainty (episteme), the author of this study elaborates the forms which these polar opposites have taken in some twentieth century writers and then, in greater detail, in the writings of Thomas Aquinas. Profiting from subsequent more sophisticated theories of probability, he examines how Aquinas’s judgments about everything from God to gossip depend on schematizations of the polarity between the systematic and the non-systematic: (...) revelation/reason, science/opinion, saints/philosophers, Aristotle/others. Post-medieval developments have provided the means to discern within Thomas’s thought both a logical theory and a kind of relative frequency theory of probability. The former depends on Aristotle’s theory of demonstration, the latter on his theory of an orderly cosmos; but each as used by Thomas lead to convictions that are sometimes naive, sometimes amusing or even terrifying. (shrink)

We study the phenomenon of merging of opinions for computationally limited Bayesian agents from the perspective of algorithmic randomness. When they agree on which data streams are algorithmically random, two Bayesian agents beginning the learning process with different priors may be seen as having compatible beliefs about the global uniformity of nature. This is because the algorithmically random data streams are of necessity globally regular: they are precisely the sequences that satisfy certain important statistical laws. By virtue of agreeing on (...) what data streams are algorithmically random, two Bayesian agents can thus be taken to concur on what global regularities they expect to see in the data. We show that this type of compatibility between priors suffices to ensure that two computable Bayesian agents will reach inter-subjective agreement with increasing information. In other words, it guarantees that their respective probability assignments will almost surely become arbitrarily close to each other as the number of observations increases. Thus, when shared by computable Bayesian learners with different subjective priors, the beliefs about uniformity captured by algorithmic randomness provably lead to merging of opinions. (shrink)

Arguably, Hume's greatest single contribution to contemporary philosophy of science has been the problem of induction (1739). Before attempting its statement, we need to spend a few words identifying the subject matter of this corner of epistemology. At a first pass, induction concerns ampliative inferences drawn on the basis of evidence (presumably, evidence acquired more or less directly from experience)—that is, inferences whose conclusions are not (validly) entailed by the premises. Philosophers have historically drawn further distinctions, often appropriating the term (...) “induction” to mark them; since we will not be concerned with the philosophical issues for which these distinctions are relevant, we will use the word “inductive” in a catch-all sense synonymous with “ampliative”. But we will follow the usual practice of choosing, as our paradigm example of inductive inferences, inferences about the future based on evidence drawn from the past and present. A further refinement is more important. Opinion typically comes in degrees, and this fact makes a great deal of difference to how we understand inductive inferences. For while it is often harmless to talk about the conclusions that can be rationally believed on the basis of some.. (shrink)

Accounts of arguments from expert opinion take it for granted that expert judgments count as (defeasible) evidence for propositions, and so an argument that proceeds from premises about what an expert judges to a conclusion that the expert is probably right is a strong argument. In Mizrahi (2013), I consider a potential justification for this assumption, namely, that expert judgments are significantly more likely to be true than novice judgments, and find it wanting because of empirical evidence suggesting that (...) expert judgments under uncertainty are not significantly more likely to be true than novice judgments or even chance. In this paper, I consider another potential justification for this assumption, namely, that expert judgments are not influenced by the cognitive biases novice judgments are influenced by, and find it wanting, too, because of empirical evidence suggesting that experts are vulnerable to pretty much the same cognitive biases that novices are vulnerable to. If this is correct, then the basic assumption at the core of accounts of arguments from expert opinion, namely, that expert judgments count as (defeasible) evidence for propositions, remains unjustified. (shrink)

It is the purpose of the following pages to reconsider the basic problem of induction. According to Hume the concomitance of A with B on one or more occasions gives no valid presumption that A will be accompanied by B on any other occasion. The data of experience may give rise to an association of ideas or set up mental habits, but they provide no reasonable grounds for expecting similar concomitances or sequences in future. If this is correct, we have (...) no starting point for the formation of any valid opinions about matters of fact; we remain ice-bound in a region of total scepticism. (shrink)

While Aby Warburg, in his younger years, advocated a completely rational, mathematical understanding of the world, he lost confidence in this scientific ideal later on. This article proposes that this crucial shift in perspective, redefining Warburg’s opinions about empiricism, rationality and thus cultural evolution as a whole, took place very early on, namely in the summer of 1890. The present article studies, for the first time, an unpublished student essay by Warburg on probability theory. While discussing stochastic and the (...) possibility of mathematical prediction of future events, Warburg’s belief in the infallible exactitude of numerical sciences got first cracks. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:BOOK REVIEWS 387 vs. "objective" is all no doubt rather imprecise, but points toward an important truth. In fact, in the contrast between them, we can see, I believe, not merely a clash of methods, standards or styles in writing history, but, more deeply still, an instance of the general antithesis between a "formalist" and a "sympathetic" sensibility, one encountered over and over in humanistic studies.6 PLATO New in (...) this section is an essay on "Some Controversial Points of Plato Interpretation Reconsidered" (pp. 183-209). Its first two parts combat the view that Plato ever gave up the metaphysics of his "middle period," but they do so only by rehearsing familiar theses about the Idea of the Good and the "two worlds" theory. These pages afford nothing new (apart from an extremely unfortunate appeal [p. 185 and again on p. 230] to an Homeric usage of the genitive to settle a problem at Rep. 518C9). The third part (pp. 194209 ) expands upon some views about later Plato for which Mme. de Vogel is already widely known, and these are very useful indeed. They offer a welcome expansion and defense of her view that in order to "do justice" (196-197, cf. 228) to the famous phrase,o) 7r,,v,e)~r ~v,t at Soph. 248E7, we must concede that Plato came to assign "the motion of a thinking mind" (208-209) to the very being of the Ideas, i.e., came to regard "the intelligibleworld as a vo~r (p. 194). Two interesting objections to her reading are confronted at some length (pp. 200-206) and several others are more briefly dealt with, thus affording her a good chance to explain her view. Valuable as these pages are, however, their upshot is rather unsatisfactory: just what Plato's view would, on her reading of it, really come to, remains mightily obscure--an obscurity she tends to concede but to explain away as Plato's "seeming peculiar to a modern mind" though we can get some grip upon his views if we but "take the trouble to follow his lead" (pp. 201, 198; cf. pp. 228-230, etc.). Such reminders of the genuine strangeness of Plato's view can no doubt be healthy in themselves, but can also be stultifying when reiterated in the face of genuine dissatisfaction with the sense that she makes of his meaning. This situation is not helped by the fact that, at crucial junctures in her argument, she buttresses her case about Plato's meaning by appeals to Aristotle's report at de Anima 1.2, 404b18-27 (see pp. 193-194, 199-200, 208, 277-281, 384-385). As she rightly reports (pp. 280, 385), Prof. Harold Cherniss has vigorously opposed the view that Aristotle is there giving Plato's view at all; yet--despite the fact that she has dedicated this volume to Cherniss--she never makes any reference to his most extended and most powerful defense of his position on this text, and much less does she attempt to answer his argument. (See Cherniss' review of H. D. Saffrey's book--a book to which de Vogel does refer, and repeatedly--in Gnomon 31 [1959], 36-51.) This matter is crucial, not merely as a bibliographical nicety, but because she tends to argue ]rom this text, maintaining that, however peculiar and isolated the sense of Soph. 248-249 and of certain phrases in the Timaeus may, on her reading of them, seem, this text proves that Plato must be read in her way. If it is not about Plato's view at all, it of course proves no such thing. The full weight of her argument will thus be borne by her view of how best to "do justice" to the text of Soph. 248E. Though she makes a clear and reasonable case 6 See Leo Steinberg's comments on this contrast as encountered in current art criticism: Other Criteria (Oxford: Oxford University Press, 1972), Essay 3 (especially pp. 63-68). His remarks about the prescriptive or "interdictory stance" of formalism also fit an important aspect of Burkert's book--an aspect which, though not articulated by her, accounts (I suspect... (shrink)

Most handbooks on statistics and the theory of probability leave the reader in a mysterious tangle of mathematical rules for computing apparently arbitrarily chosen numerical functions. At first sight, then, a treatise on the Logical Foundations of Probability raises hopes that it will be a guide to clarity in these matters. These hopes are strengthened if the reader remembers that the author, Professor Rudolph Carnap of the University of Chicago, is noted for his thesis that philosophy is the (...) study of the logic of science. On the other hand, a first glance into this book may discourage a reader who, though familiar with statistics, is not familiar with modern logic and its notation. For this reason particularly I shall try to give an account of this book that will enable the interested student to form some opinion of its usefulness to him. (shrink)

The question of how the probabilistic opinions of different individuals should be aggregated to form a group opinion is controversial. But one assumption seems to be pretty much common ground: for a group of Bayesians, the representation of group opinion should itself be a unique probability distribution, 410–414, [45]; Bordley Management Science, 28, 1137–1148, [5]; Genest et al. The Annals of Statistics, 487–501, [21]; Genest and Zidek Statistical Science, 114–135, [23]; Mongin Journal of Economic Theory, 66, 313–351, (...) [46]; Clemen and Winkler Risk Analysis, 19, 187–203, [7]; Dietrich and List [14]; Herzberg Theory and Decision, 1–19, [28]). We argue that this assumption is not always in order. We show how to extend the canonical mathematical framework for pooling to cover pooling with imprecise probabilities by employing set-valued pooling functions and generalizing common pooling axioms accordingly. As a proof of concept, we then show that one IP construction satisfies a number of central pooling axioms that are not jointly satisfied by any of the standard pooling recipes on pain of triviality. Following Levi, 3–11, [39]), we also argue that IP models admit of a much better philosophical motivation as a model of rational consensus. (shrink)

As van Fraassen pointed out in his opening remarks, Henry Kyburg's lottery paradox has long been known to raise difficulties in attempts to represent full belief as a probability greater than or equal to p, where p is some number less than 1. Recently, Patrick Maher has pointed out that to identify full belief with probability equal to 1 presents similar difficulties. In his paper, van Fraassen investigates ways of representing full belief by personal probability which avoid (...) the difficulties raised by Maher's measure-theoretic version of the lottery paradox. Van Fraassen's more subtle representation dissolves the simple identification of full belief with maximal personal probability. His investigation exploits the richer resources for representing opinion provided by taking conditional, rather than unconditional, personal probability as fundamental. It has interesting implications for equivalent alternative approaches based on non-Archimedean probability, as well as for equivalent approaches in which assumption contexts representing full belief relative to suppositions are taken as fundamental. (shrink)

The theorem of convergence of opinions is an important theorem in the subjective theory of probability.It demonstrates that the subjectivity of a prior probability will be substituted with the objectivity of a posterior probability as evidences increase.The theorem of convergence of opinions is regarded as the dynamic principle of rationality concerning the subjective probability,and therefore is used to resolve Hume's problem,i.e.,the problem of inductive rationality.However,Hacking convincingly argues that the theorem of convergence of opinions is not about (...) the convergence of a posterior probability Pre(h),but about the convergence of a conditional probability Pr(h/e).The subjective theory of probability implies a tacit acceptance of an equation that is Pre(h)=Pr(h/e),usually called "the rule of conditionalisation".Thus,the problem of rationality of induction is converted into one concerning the rule of conditionalisation.In this paper a new principle of rationality(the principle of minimum number of initial probabilities)is put forward,which,in combination with the concept of "local rationality",offers a justification for the rule of conditionalisation. (shrink)

This ambitious study, by a professor of rhetoric, proposes itself as "intellectual history in a traditional sense" and not as philosophical discourse. Though philosophy does not appear in its title, however, much of its content will appear to philosophers as pertaining to their discipline, and the thesis it develops surely commends itself to philosophical critique. The author's aim, at least in part, is to challenge "the commonly held view" that the scientific revolution created or intensified the modern division between the (...) humanities and the sciences. In the early Renaissance, she argues, rhetoric and philosophy were seen as "pursuing different goals by different means," with rhetoric assigned to the humanities and concerned with opinion and probability and science assigned to philosophy and concerned with truth and certainty. Such a dichotomy was broken down at the onset of the modern period, she holds, particularly in seventeenth-century England, where a sceptical approach to knowledge made for common ground between humanists and scientists. The weakening of knowledge claims in the probabilistic empiricism of the period is thus, for her, the key to understanding its intellectual life and the climate of opinion in which it flourished. To make the point she devotes successive chapters to natural philosophy and empirical science; religion; history; law; witchcraft; and language, communication, and literature. The presentation is scholarly throughout and well documented in an abundance of notes at the end of the volume. Considering the difficulty of her thesis and its extremely broad range the author argues her case well; yet there are problems with it that make one wonder whether her generalization can claim validity in anything more than a trivial sense. (shrink)

A portrait of scholastic approaches to a qualified disagreement of opinions, focusing on the antagonism of scholastic probabilism and anti-probabilism in the early modern era.

I discuss three puzzles of probability theory which seem connected with problems of direct reference and rigid designation. The resolution of at least one of them requires referential use of definite descriptions in probability statements. I argue that contrary to common opinion all these puzzles are in a way still unsolved: They seem to exemplify cases in which a change of probabilities is rationally required, even though any specific change presupposes unjustified assumptions.

A number of experts receive noisy signals regarding a desirable public decision. The public target is to make the best possible decision on the basis of all the information held by the experts. We compare two ``cultures.'' In one, all experts are driven only by the public motive to increase the probability that the desirable action will be taken. In the second, each expert is also driven by a private motive: to have his recommendation accepted. We show that in (...) the first culture, every mechanism will have an equilibrium which does not achieve the public target, whereas the second culture gives rise to a mechanism whose unique equilibrium outcome does achieve the public target. Journal of Economic Literature Classification Numbers: C72, D71. (shrink)

A persistent question about the deBroglie–Bohm interpretation of quantum mechanics concerns the understanding of Born’s rule in the theory. Where do the quantum mechanical probabilities come from? How are they to be interpreted? These are the problems of emergence and interpretation. In more than 50 years no consensus regarding the answers has been achieved. Indeed, mirroring the foundational disputes in statistical mechanics, the answers to each question are surprisingly diverse. This paper is an opinionated survey of this literature. While acknowledging (...) the pros and cons of various positions, it defends particular answers to how the probabilities emerge from Bohmian mechanics and how they ought to be interpreted. (shrink)

A persistent question about the deBroglie–Bohm interpretation of quantum mechanics concerns the understanding of Born’s rule in the theory. Where do the quantum mechanical probabilities come from? How are they to be interpreted? These are the problems of emergence and interpretation. In more than 50 years no consensus regarding the answers has been achieved. Indeed, mirroring the foundational disputes in statistical mechanics, the answers to each question are surprisingly diverse. This paper is an opinionated survey of this literature. While acknowledging (...) the pros and cons of various positions, it defends particular answers to how the probabilities emerge from Bohmian mechanics and how they ought to be interpreted. (shrink)

Examining the social and political upheavals that characterized the collapse of public judgment in early modern Europe, Liberating Judgment offers a unique account of the achievement of liberal democracy and self-government. The book argues that the work of John Locke instills a civic judgment that avoids the excesses of corrosive skepticism and dogmatic fanaticism, which lead to either political acquiescence or irresolvable conflict. Locke changes the way political power is assessed by replacing deteriorating vocabularies of legitimacy with a new language (...) of justification informed by a conception of probability. For Locke, the coherence and viability of liberal self-government rests not on unassailable principles or institutions, but on the capacity of citizens to embrace probable judgment. The book explores the breakdown of the medieval understanding of knowledge and opinion, and considers how Montaigne's skepticism and Descartes' rationalism--interconnected responses to the crisis--involved a pragmatic submission to absolute rule. Locke endorses this response early on, but moves away from it when he encounters a notion of reasonableness based on probable judgment. In his mature writings, Locke instructs his readers to govern their faculties and intellectual yearnings in accordance with this new standard as well as a vocabulary of justification that might cultivate a self-government of free and equal individuals. The success of Locke's arguments depends upon citizens' willingness to take up the labor of judgment in situations where absolute certainty cannot be achieved. (shrink)

Merging of opinions results underwrite Bayesian rejoinders to complaints about the subjective nature of personal probability. Such results establish that sufficiently similar priors achieve consensus in the long run when fed the same increasing stream of evidence. Initial subjectivity, the line goes, is of mere transient significance, giving way to intersubjective agreement eventually. Here, we establish a merging result for sets of probability measures that are updated by Jeffrey conditioning. This generalizes a number of different merging results in (...) the literature. We also show that such sets converge to a shared, maximally informed opinion. Convergence to a maximally informed opinion is a (weak) Jeffrey conditioning analogue of Bayesian “convergence to the truth” for conditional probabilities. Finally, we demonstrate the philosophical significance of our study by detailing applications to the topics of dynamic coherence, imprecise probabilities, and probabilistic opinion pooling. (shrink)

This dissertation is a contribution to formal and computational philosophy. -/- In the first part, we show that by exploiting the parallels between large, yet finite lotteries on the one hand and countably infinite lotteries on the other, we gain insights in the foundations of probability theory as well as in epistemology. Case 1: Infinite lotteries. We discuss how the concept of a fair finite lottery can best be extended to denumerably infinite lotteries. The solution boils down to the (...) introduction of infinitesimal probability values, which can be achieved using non-standard analysis. Our solution can be generalized to uncountable sample spaces, giving rise to a Non-Archimedean Probability (NAP) theory. Case 2: Large but finite lotteries. We propose application of the language of relative analysis (a type of non-standard analysis) to formulate a new model for rational belief, called Stratified Belief. This contextualist model seems well-suited to deal with a concept of beliefs based on probabilities ‘sufficiently close to unity’. -/- The second part presents a case study in social epistemology. We model a group of agents who update their opinions by averaging the opinions of other agents. Our main goal is to calculate the probability for an agent to end up in an inconsistent belief state due to updating. To that end, an analytical expression is given and evaluated numerically, both exactly and using statistical sampling. The probability of ending up in an inconsistent belief state turns out to be always smaller than 2%. (shrink)

A number of experts receive noisy signals regarding a desirable public decision. The public target is to make the best possible decision on the basis of all the information held by the experts. We compare two ``cultures.'' In one, all experts are driven only by the public motive to increase the probability that the desirable action will be taken. In the second, each expert is also driven by a private motive: to have his recommendation accepted. We show that in (...) the first culture, every mechanism will have an equilibrium which does not achieve the public target, whereas the second culture gives rise to a mechanism whose unique equilibrium outcome does achieve the public target. Journal of Economic Literature Classification Numbers: C72, D71. 1998 Academic Press.. (shrink)

How can different individuals' probability assignments to some events be aggregated into a collective probability assignment? Classic results on this problem assume that the set of relevant events -- the agenda -- is a sigma-algebra and is thus closed under disjunction (union) and conjunction (intersection). We drop this demanding assumption and explore probabilistic opinion pooling on general agendas. One might be interested in the probability of rain and that of an interest-rate increase, but not in the (...) probability of rain or an interest-rate increase. We characterize linear pooling and neutral pooling for general agendas, with classic results as special cases for agendas that are sigma-algebras. As an illustrative application, we also consider probabilistic preference aggregation. Finally, we compare our results with existing results on binary judgment aggregation and Arrovian preference aggregation. This paper is the first of two self-contained, but technically related companion papers inspired by binary judgment-aggregation theory. (shrink)

How can different individuals' probability functions on a given sigma-algebra of events be aggregated into a collective probability function? Classic approaches to this problem often require 'event-wise independence': the collective probability for each event should depend only on the individuals' probabilities for that event. In practice, however, some events may be 'basic' and others 'derivative', so that it makes sense first to aggregate the probabilities for the former and then to let these constrain the probabilities for the (...) latter. We formalize this idea by introducing a 'premise-based' approach to probabilistic opinion pooling, and show that, under a variety of assumptions, it leads to linear or neutral opinion pooling on the 'premises'. This paper is the second of two self-contained, but technically related companion papers inspired by binary judgment-aggregation theory. (shrink)

Suppose several individuals (e.g., experts on a panel) each assign probabilities to some events. How can these individual probability assignments be aggregated into a single collective probability assignment? This article reviews several proposed solutions to this problem. We focus on three salient proposals: linear pooling (the weighted or unweighted linear averaging of probabilities), geometric pooling (the weighted or unweighted geometric averaging of probabilities), and multiplicative pooling (where probabilities are multiplied rather than averaged). We present axiomatic characterisations of each (...) class of pooling functions (most of them classic, but one new) and argue that linear pooling can be justified procedurally, but not epistemically, while the other two pooling methods can be justified epistemically. The choice between them, in turn, depends on whether the individuals' probability assignments are based on shared information or on private information. We conclude by mentioning a number of other pooling methods. (shrink)

In complex systems, agents often interact with others in two distinct types of interactions, pairwise interaction and group interaction. The Deffuant–Weisbuch model adopting pairwise interaction and the Hegselmann–Krause model adopting group interaction are the two most widely studied opinion dynamics. In this study, we propose a novel opinion dynamics by combining pairwise and group interactions for agents and study the effects of the combination on consensus in the population. In the model, we introduce a parameter α to control (...) the weights of the two interactions in the dynamics. Through numerical simulations, we find that there exists an optimal α, which can lead to a highest probability of complete consensus and minimum critical bounded confidence for the formation of consensus. Furthermore, we show the effects of α on opinion formation by presenting the observations for opinion clusters. Moreover, we check the robustness of the results on different network structures and find the promotion of opinion consensus by α not limited to a complete graph. (shrink)

It is a consequence of the theory of imprecise credences that there exist situations in which rational agents inevitably become less opinionated toward some propositions as they gather more evidence. The fact that an agent's imprecise credal state can dilate in this way is often treated as a strike against the imprecise approach to inductive inference. Here, we show that dilation is not a mere artifact of this approach by demonstrating that opinion loss is countenanced as rational by a (...) substantially broader class of normative theories than has been previously recognised. Specifically, we show that dilation-like phenomena arise even when one abandons the basic assumption that agents have (precise or imprecise) credences of any kind, and follows directly from bedrock norms for rational comparative confidence judgements of the form `I am at least as confident in p as I am in q'. We then use the comparative confidence framework to develop a novel understanding of what exactly gives rise to dilation-like phenomena. By considering opinion loss in this more general setting, we are able to provide a novel assessment of the prospects for an account of inductive inference that is not saddled with the inevitability of rational opinion loss. (shrink)

Let us begin with what all of us here agree on: folk psychology is not immune to revision. It has a certain vulnerability in principle. Any particular part of it might be overthrown and replaced by some other doctrine. Yet we disagree about how likely it is that that vulnerability in principle will turn into the actual demise of large portions--or all--of folk psychology. I am of the view that folk psychology is here for the long haul, and for some (...) very good reasons. But I am not going to concentrate on that in my remarks. What nobody has bothered saying here yet, but is probably worth saying, is that for all of its blemishes, warts and perplexities, folk psychology is an extraordinarily powerful source of prediction. It is not just prodigiously powerful but remarkably easy for human beings to use. We are virtuoso exploiters of not so much a theory as a craft. That is, we might better call it a folk craft rather than a folk theory. The theory of folk psychology is the ideology about the craft, and there is lots of room, as anthropologists will remind us, for false ideology. (shrink)

This issue was discussed with regard to chosen commentaries to Aristotle’s treatise De anima, formed in the so-called via moderna mainstream, in particular those of John Buridan, Nicole Oresme and Laurentius of Lindores. In such a context, the Cracovian commentaries referring to Parisian nominalists were presented by those of Benedict Hesse and Anonymus. The analyses carried out above allow one to ascertain that although William of Ockham’s opinion questioning the possibility of knowledge of the soul in the field of (...) philosophy, nominalists of the late Middle Ages did not resign from speculation on the beginning and the separation from the body of the soul, also the fate of the soul after death. They focused on the nature of the matter – human body and his relation with the soul – in the moment of birth. In the aspect of death 14th century scholars undertook the struggle, which was one with the justification of the psycho-physical unity of the human being existing after death solely as an immortal soul. In both thems, they tried to find their solutions, while if they could not solve these aporeticals questions – they had the courage to admit, that is not possible by solely relying on the natural forces of reason. They had to refer to the teaching of christianity, without however falling prey to fideism. This was a methodical endeavour based on the experience that natural reason in searching for the truth is not capable of its own efforts to attain to certain concepts and might on occasion err, it is then that faith becomes its guide and supplies it with more acceptable solutions. This is the courage of one of the greatest philosophers – Plato, who said that you have to have this “great courage” to undertake only probable knowledge, when another is not possible. (shrink)

Recently, Kirchhoff and Kiverstein have argued that the extended consciousness thesis, namely the claim that the material vehicles of consciousness extend beyond our heads, is entirely compatible with, and actually mandated by, a correct interpretation of the predictive processing framework. To do so, they rely on a potent argument in favor of the extended consciousness thesis, namely the Dynamical Entanglement and Unique Temporal Signature (DEUTS) argument. Here, we will critically examine Kirchhoff and Kiverstein’s endeavor, arguing for the following three claims. (...) First, we will claim that Kirchhoff and Kiverstein’s emphasis on culture and cultural practices does not help them substantiate the extended consciousness thesis. Secondly, we will argue that the way in which Kirchhoff and Kiverstein formalize the boundaries of a subject’s conscious mind is inadequate, as it yields conclusions running counter some of their assumptions. Lastly, we will argue that the DEUTS argument does not establish the extended consciousness thesis, as it licenses a phenomenal bloat objection which is exactly analogous to the “cognitive bloat” objection to the extended mind thesis. We will thus conclude that Kirchhoff and Kiverstein’s proposed marriage between the extended consciousness thesis and predictive processing fails, and that, contrary to a popular opinion, DEUTS is not a strong argument in favor of the extended consciousness thesis. (shrink)

There are many reasons we might want to take the opinions of various individuals and pool them to give the opinions of the group they constitute. If all the individuals in the group have probabilistic opinions about the same propositions, there is a host of pooling functions we might deploy, such as linear or geometric pooling. However, there are also cases where different members of the group assign probabilities to different sets of propositions, which might overlap a lot, a little, (...) or not at all. There are far fewer proposals for how to proceed in these cases, and those there are have undesirable features. I begin by considering four proposals and arguing that they don't work. Then I'll describe my own proposal, which is intended to cover the situation in which we want to pool the individual opinions in order to ascribe an opinion to the group considered as an agent in its own right. (shrink)

The appeal to expert opinion is an argument form that uses the verdict of an expert to support a position or hypothesis. A previous scheme-based treatment of the argument form is formalized within a Bayesian network that is able to capture the critical aspects of the argument form, including the central considerations of the expert's expertise and trustworthiness. We propose this as an appropriate normative framework for the argument form, enabling the development and testing of quantitative predictions as to (...) how people evaluate this argument, suggesting that such an approach might be beneficial to argumentation research generally. We subsequently present two experiments as an example of the potential for future research in this vein, demonstrating that participants' quantitative ratings of the convincingness of a proposition that has been supported with an appeal to expert opinion were broadly consistent with the predictions of the Bayesian model. (shrink)

It is often suggested that when opinions differ among individuals in a group, the opinions should be aggregated to form a compromise. This paper compares two approaches to aggregating opinions, linear pooling and what I call opinion agglomeration. In evaluating both strategies, I propose a pragmatic criterion, No Regrets, entailing that an aggregation strategy should prevent groups from buying and selling bets on events at prices regretted by their members. I show that only opinion agglomeration is able to (...) satisfy the demand. I then proceed to give normative and empirical arguments in support of the pragmatic criterion for opinion aggregation, and that ultimately favor opinion agglomeration. (shrink)