33 found
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  1. Two Problems of Direct Inference.Paul D. Thorn - 2012 - Erkenntnis 76 (3):299-318.
    The article begins by describing two longstanding problems associated with direct inference. One problem concerns the role of uninformative frequency statements in inferring probabilities by direct inference. A second problem concerns the role of frequency statements with gerrymandered reference classes. I show that past approaches to the problem associated with uninformative frequency statements yield the wrong conclusions in some cases. I propose a modification of Kyburg’s approach to the problem that yields the right conclusions. Past theories of direct inference have (...)
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  2. On the preference for more specific reference classes.Paul D. Thorn - 2017 - Synthese 194 (6):2025-2051.
    In attempting to form rational personal probabilities by direct inference, it is usually assumed that one should prefer frequency information concerning more specific reference classes. While the preceding assumption is intuitively plausible, little energy has been expended in explaining why it should be accepted. In the present article, I address this omission by showing that, among the principled policies that may be used in setting one’s personal probabilities, the policy of making direct inferences with a preference for frequency information for (...)
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  3.  76
    The Revenge of Ecological Rationality: Strategy-Selection by Meta-Induction Within Changing Environments.Gerhard Schurz & Paul D. Thorn - 2016 - Minds and Machines 26 (1-2):31-59.
    According to the paradigm of adaptive rationality, successful inference and prediction methods tend to be local and frugal. As a complement to work within this paradigm, we investigate the problem of selecting an optimal combination of prediction methods from a given toolbox of such local methods, in the context of changing environments. These selection methods are called meta-inductive strategies, if they are based on the success-records of the toolbox-methods. No absolutely optimal MI strategy exists—a fact that we call the “revenge (...)
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  4. A Utility Based Evaluation of Logico-probabilistic Systems.Paul D. Thorn & Gerhard Schurz - 2014 - Studia Logica 102 (4):867-890.
    Systems of logico-probabilistic (LP) reasoning characterize inference from conditional assertions interpreted as expressing high conditional probabilities. In the present article, we investigate four prominent LP systems (namely, systems O, P, Z, and QC) by means of computer simulations. The results reported here extend our previous work in this area, and evaluate the four systems in terms of the expected utility of the dispositions to act that derive from the conclusions that the systems license. In addition to conforming to the dominant (...)
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  5. Undercutting defeat via reference properties of differing arity: a reply to Pust.Paul D. Thorn - 2011 - Analysis 71 (4):662-667.
    In a recent article, Joel Pust argued that direct inference based on reference properties of differing arity are incommensurable, and so direct inference cannot be used to resolve the Sleeping Beauty problem. After discussing the defects of Pust's argument, I offer reasons for thinking that direct inferences based on reference properties of differing arity are commensurable, and that we should prefer direct inferences based on logically stronger reference properties, regardless of arity.
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  6. Against Deductive Closure.Paul D. Thorn - 2017 - Theoria 83 (2):103-119.
    The present article illustrates a conflict between the claim that rational belief sets are closed under deductive consequences, and a very inclusive claim about the factors that are sufficient to determine whether it is rational to believe respective propositions. Inasmuch as it is implausible to hold that the factors listed here are insufficient to determine whether it is rational to believe respective propositions, we have good reason to deny that rational belief sets are closed under deductive consequences.
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  7.  80
    Reward versus risk in uncertain inference: Theorems and simulations.Gerhard Schurz & Paul D. Thorn - 2012 - Review of Symbolic Logic 5 (4):574-612.
    Systems of logico-probabilistic reasoning characterize inference from conditional assertions that express high conditional probabilities. In this paper we investigate four prominent LP systems, the systems _O, P_, _Z_, and _QC_. These systems differ in the number of inferences they licence _. LP systems that license more inferences enjoy the possible reward of deriving more true and informative conclusions, but with this possible reward comes the risk of drawing more false or uninformative conclusions. In the first part of the paper, we (...)
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  8. The joint aggregation of beliefs and degrees of belief.Paul D. Thorn - 2018 - Synthese 197 (12):5389-5409.
    The article proceeds upon the assumption that the beliefs and degrees of belief of rational agents satisfy a number of constraints, including: consistency and deductive closure for belief sets, conformity to the axioms of probability for degrees of belief, and the Lockean Thesis concerning the relationship between belief and degree of belief. Assuming that the beliefs and degrees of belief of both individuals and collectives satisfy the preceding three constraints, I discuss what further constraints may be imposed on the aggregation (...)
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  9. Qualitative probabilistic inference under varied entropy levels.Paul D. Thorn & Gerhard Schurz - 2016 - Journal of Applied Logic 19 (2):87-101.
    In previous work, we studied four well known systems of qualitative probabilistic inference, and presented data from computer simulations in an attempt to illustrate the performance of the systems. These simulations evaluated the four systems in terms of their tendency to license inference to accurate and informative conclusions, given incomplete information about a randomly selected probability distribution. In our earlier work, the procedure used in generating the unknown probability distribution (representing the true stochastic state of the world) tended to yield (...)
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  10. Meta-Induction and the Wisdom of Crowds.Paul D. Thorn & Gerhard Schurz - 2012 - Analyse & Kritik 34 (2):339-366.
    Meta-induction, in its various forms, is an imitative prediction method, where the prediction methods and the predictions of other agents are imitated to the extent that those methods or agents have proven successful in the past. In past work, Schurz demonstrated the optimality of meta-induction as a method for predicting unknown events and quantities. However, much recent discussion, along with formal and empirical work, on the Wisdom of Crowds has extolled the virtue of diverse and independent judgment as essential to (...)
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  11. Defeasible Conditionalization.Paul D. Thorn - 2014 - Journal of Philosophical Logic 43 (2-3):283-302.
    The applicability of Bayesian conditionalization in setting one’s posterior probability for a proposition, α, is limited to cases where the value of a corresponding prior probability, PPRI(α|∧E), is available, where ∧E represents one’s complete body of evidence. In order to extend probability updating to cases where the prior probabilities needed for Bayesian conditionalization are unavailable, I introduce an inference schema, defeasible conditionalization, which allows one to update one’s personal probability in a proposition by conditioning on a proposition that represents a (...)
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  12.  34
    The stimulus-to-perception connection: a simulation study in the epistemology of perception.Paul D. Thorn - 2020 - Synthese 199 (1-2):551-578.
    The present paper introduces a simple framework for modeling the relationship between environmental states, perceptual states, and action. The framework represents situations where an agent’s perceptual state forms the basis for choosing an action, and what action the agent performs determines the agent’s payoff, as a function of the environmental conditions in which the action is performed. The framework is used as the basis for a simulation study of the sorts of correspondence between perceptual and environmental states that are important (...)
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  13.  49
    A Formal Solution to Reichenbach's Reference Class Problem.Paul D. Thorn - 2019 - Dialectica 73 (3):349-366.
  14.  33
    How Category Selection Impacts Inference Reliability: Inheritance Inference From an Ecological Perspective.Paul D. Thorn & Gerhard Schurz - 2021 - Cognitive Science 45 (4):e12971.
    This article presents results from a simulation‐based study of inheritance inference, that is, inference from the typicality of a property among a “base” class to its typicality among a subclass of the class. The study aims to ascertain which kinds of inheritance inferences are reliable, with attention to the dependence of their reliability upon the type of environment in which inferences are made. For example, the study addresses whether inheritance inference is reliable in the case of “exceptional subclasses” (i.e., subclasses (...)
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  15.  8
    Induction With and Without Natural Properties: a New Approach to the New Riddle of Induction.Paul D. Thorn & Gerhard Schurz - forthcoming - Philosophia:1-24.
    Drawing on past work, we introduce a new approach to the New Riddle of Induction, showing that the inductive projection of gruesome properties is unreliable under particular ideal conditions that are sufficient for the reliable inductive projection of non-gruesome properties. As an auxiliary to our account, we introduce rules for resolving conflicts between background information and the conclusions of otherwise reliable inductive inferences. Our approach to the New Riddle of Induction is quite permissive in the range of properties it recognizes (...)
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  16. Qualitative Probabilistic Inference with Default Inheritance.Paul D. Thorn, Christian Eichhorn, Gabriele Kern-Isberner & Gerhard Schurz - 2015 - In Christoph Beierle, Gabriele Kern-Isberner, Marco Ragni & Frieder Stolzenburg (eds.), Proceedings of the KI 2015 Workshop on Formal and Cognitive Reasoning. pp. 16-28.
    There are numerous formal systems that allow inference of new conditionals based on a conditional knowledge base. Many of these systems have been analysed theoretically and some have been tested against human reasoning in psychological studies, but experiments evaluating the performance of such systems are rare. In this article, we extend the experiments in [19] in order to evaluate the inferential properties of c-representations in comparison to the well-known Systems P and Z. Since it is known that System Z and (...)
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  17. Direct Inference from Imprecise Frequencies.Paul D. Thorn - 2017 - In Michela Massimi, Jan-Willem Romeijn & Gerhard Schurz (eds.), EPSA15 Selected Papers: The 5th conference of the European Philosophy of Science Association in Düsseldorf. Cham: Springer. pp. 347-358.
    It is well known that there are, at least, two sorts of cases where one should not prefer a direct inference based on a narrower reference class, in particular: cases where the narrower reference class is gerrymandered, and cases where one lacks an evidential basis for forming a precise-valued frequency judgment for the narrower reference class. I here propose (1) that the preceding exceptions exhaust the circumstances where one should not prefer direct inference based on a narrower reference class, and (...)
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  18. TTB vs. Franklin's Rule in Environments of Different Redundancy.Gerhard Schurz & Paul D. Thorn - 2014 - Frontiers in Psychology 5:15-16.
    This addendum presents results that confound some commonly made claims about the sorts of environments in which the performance of TTB exceeds that of Franklin's rule, and vice versa.
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  19. Cognitivist Probabilism.Paul D. Thorn - 2013 - In Vit Puncochar & Petr Svarny (eds.), The Logica Yearbook 2012. College Publications. pp. 201-213.
    In this article, I introduce the term “cognitivism” as a name for the thesis that degrees of belief are equivalent to full beliefs about truth-valued propositions. The thesis (of cognitivism) that degrees of belief are equivalent to full beliefs is equivocal, inasmuch as different sorts of equivalence may be postulated between degrees of belief and full beliefs. The simplest sort of equivalence (and the sort of equivalence that I discuss here) identifies having a given degree of belief with having a (...)
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  20. Wise Crowds, Clever Meta-Inductivists.Paul D. Thorn - 2015 - In Uskali Mäki, Stéphanie Ruphy, Gerhard Schurz & Ioannis Votsis (eds.), Recent Developments in the Philosophy of Science. Cham: Springer. pp. 71-86.
    Formal and empirical work on the Wisdom of Crowds has extolled the virtue of diverse and independent judgment as essential to the maintenance of ‘wise crowds’. In other words, com-munication and imitation among members of a group may have the negative effect of decreasing the aggregate wisdom of the group. In contrast, it is demonstrable that certain meta-inductive methods provide optimal means for predicting unknown events. Such meta-inductive methods are essentially imitative, where the predictions of other agents are imitated to (...)
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  21. A Note Concerning Infinite Regresses of Deferred Justification.Paul D. Thorn - 2017 - Philosophia 45 (1):349-357.
    An agent’s belief in a proposition, E0, is justified by an infinite regress of deferred justification just in case the belief that E0 is justified, and the justification for believing E0 proceeds from an infinite sequence of propositions, E0, E1, E2, etc., where, for all n ≥ 0, En+1 serves as the justification for En. In a number of recent articles, Atkinson and Peijnenburg claim to give examples where a belief is justified by an infinite regress of deferred justification. I (...)
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  22. Attractivity Weighting: Take-the-Best's Foolproof Sibling.Paul D. Thorn & Gerhard Schurz - 2016 - In A. Papafragou, D. Grodner, D. Mirman & J. C. Trueswell (eds.), Proceedings of the 38th Annual Conference of the Cognitive Science Society (pp. 432-437) Cognitive Science Society. Cognitive Science Society. pp. 456-461.
    We describe a prediction method called "Attractivity Weighting" (AW). In the case of cue-based paired comparison tasks, AW's prediction is based on a weighted average of the cue values of the most successful cues. In many situations, AW's prediction is based on the cue value of the most successful cue, resulting in behavior similar to Take-the-Best (TTB). Unlike TTB, AW has a desirable characteristic called "access optimality": Its long-run success is guaranteed to be at least as great as the most (...)
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  23. Ampliative Inference Under Varied Entropy Levels.Paul D. Thorn & Gerhard Schurz - 2013 - In Christoph Beierle & Gabriele Kern-Isberner (eds.), Proceedings of the 4th Workshop on Dynamics of Knowledge and Belief (DKB-2013). Fakultät für Mathematik und Informatik, FernUniversität in Hagen. pp. 77-88.
  24.  67
    The Inheritance of Defaults in the Case of Exceptional Subclasses.Paul D. Thorn - 2015 - The Reasoner 9 (11):93.
  25. Paraconsistency and the image of science.Paul D. Thorn - 2001 - In Bryson Brown & John Woods (eds.), Logical Consequence: Rival Approaches. Hermes.
  26. An Objectivist Argument for Thirdism.Ian Evans, Don Fallis, Peter Gross, Terry Horgan, Jenann Ismael, John Pollock, Paul D. Thorn, Jacob N. Caton, Adam Arico, Daniel Sanderman, Orlin Vakerelov, Nathan Ballantyne, Matthew S. Bedke, Brian Fiala & Martin Fricke - 2008 - Analysis 68 (2):149-155.
    Bayesians take “definite” or “single-case” probabilities to be basic. Definite probabilities attach to closed formulas or propositions. We write them here using small caps: PROB(P) and PROB(P/Q). Most objective probability theories begin instead with “indefinite” or “general” probabilities (sometimes called “statistical probabilities”). Indefinite probabilities attach to open formulas or propositions. We write indefinite probabilities using lower case “prob” and free variables: prob(Bx/Ax). The indefinite probability of an A being a B is not about any particular A, but rather about the (...)
     
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  27. Construction and Revision of Spatial Mental Models under High Task Demand.Jelica Nejasmic, Leandra Bucher, Paul D. Thorn & Markus Knauff - 2014 - In Paul Bello, Marcello Guarini, Marjorie McShane & Brian Scassellati (eds.), Proceedings of the 36th Annual Conference of the Cognitive Science Society. Cognitive Science Society. pp. 1066-72.
    Individuals often revise their beliefs when confronted with contradicting evidence. Belief revision in the spatial domain can be regarded as variation of initially constructed spatial mental models. Construction and revision usually follow distinct cognitive principles. The present study examines whether principles of revisions which follow constructions under high task demands differ from principles applied after less demanding constructions. We manipulated the task demands for model constructions by means of the continuity with which a spatial model was constructed. We administered tasks (...)
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  28.  69
    Induction by Direct Inference Meets the Goodman Problem.Paul D. Thorn - 2018 - Kriterion - Journal of Philosophy 32 (2):1-24.
    I here aim to show that a particular approach to the problem of induction, which I will call “induction by direct inference”, comfortably handles Goodman’s problem of induction. I begin the article by describing induction by direct inference. After introducing induction by direct inference, I briefly introduce the Goodman problem, and explain why it is, prima facie, an obstacle to the proposed approach. I then show how one may address the Goodman problem, assuming one adopts induction by direct inference as (...)
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  29.  64
    Minimality Criteria in Spatial Belief Revision.Leandra Bucher & Paul D. Thorn - 2014 - In Paul Bello, Marcello Guarini, Marjorie McShane & Brian Scassellati (eds.), Proceedings of the 36th Annual Conference of the Cognitive Science Society. Cognitive Science Society. pp. 1952-8.
    Agents typically revise their beliefs when confronted with evidence that contradicts those beliefs, selecting from a number of possible revisions sufficient to reestablish consistency. In cases where an individual’s beliefs concern spatial relations, belief revision has been fruitfully treated as a decision about which features of an initially constructed spatial mental model to modify. A normative claim about belief revision maintains that agents should prefer minimal belief revisions. Yet recent studies have rebutted the preceding claim, where minimality is understood to (...)
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  30. The normative character of interpretation and mental explanation.Paul D. Thorn - 1998 - Dissertation, Simon Fraser University
    This essay is devoted to the study of useful ways of thinking about the nature of interpretation, with particular attention being given to the so called normative character of mental explanation. My aim of illuminating the nature of interpretation will be accomplished by examining several views, some of which are common to both Donald Davidson and Daniel Dennett, concerning its unique characteristics as a method of prediction and explanation. Moreover, some of the views held by Davidson and Dennett will be (...)
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  31. Three Problems of Direct Inference.Paul D. Thorn - 2007 - Dissertation, University of Arizona
  32.  53
    The Trouble with Pollock’s Principle of Agreement.Paul D. Thorn - 2007 - The Reasoner 1 (8):9-10.
  33. Nick Bostrom: Superintelligence: Paths, Dangers, Strategies: Oxford University Press, Oxford, 2014, xvi+328, £18.99, ISBN: 978-0-19-967811-2. [REVIEW]Paul D. Thorn - 2015 - Minds and Machines 25 (3):285-289.