Lottery Semantics: A Compositional Semantics for Probabilistic First-Order Logic with Imperfect Information

We present a compositional semantics for first-order logic with imperfect information that is equivalent to Sevenster and Sandu’s equilibrium semantics (under which the truth value of a sentence in a finite model is equal to the minimax value of its semantic game). Our semantics is a generalization of an earlier semantics developed by the first author that was based on behavioral strategies, rather than mixed strategies.     

一个匹配生成更新语义的条件句系统

条件句系统通常用择类语义来刻画,此语义对条件句逻辑来说是标准的。一个择类模型可以用一个三元组（W,f,V）来表示,其中W≠Φ,f是从P（W）×W到P（W）中的择类函数,且V是从一命题变元集PV到P（W）中的赋值函数。本文我们提出一个更新语义,它保留择类框架,但V被从PV到P（W）^P（W）中的一个更新函数代替,因为更新函数能表示动态命题而赋值函数则不能。最后我们证明一个条件句系统相对这样的语义有框架可靠性。     

On the Quantification of Model Uncertainty: A Bayesian Perspective

Psychometrika - Issues of model selection have dominated the theoretical and applied statistical literature for decades. Model selection methods such as ridge regression, the lasso, and the elastic...     

Relational Semantics and Domain Semantics for Epistemic Modals

The standard account of modal expressions in natural language analyzes them as quantifiers over a set of possible worlds determined by the evaluation world and an accessibility relation. A number of authors have recently argued for an alternative account according to which modals are analyzed as quantifying over a domain of possible worlds that is specified directly in the points of evaluation. But the new approach only handles the data motivating it if it is supplemented with a non-standard account of attitude verbs and conditionals. It can be shown the the relational account handles the same data equally well if it too is supplemented with a non-standard account of such expressions.     

The Directionality of Verbal Probability Expressions: Effects on Decisions,Predictions, and Probabilistic Reasoning

Verbal phrases denoting uncertainty are of two kinds: positive, suggesting the occurrence of a target outcome, and negative, drawing attention to its nonoccurrence (Teigen & Brun, 1995). This directionality is correlated with, but not identical to, high and low p values. Choice of phrase will in turn influence predictions and decisions. A treatment described as having “some possibility” of success will be recommended, as opposed to when it is described as “quite uncertain,” even if the probability of cure referred to by these two expressions is judged to be the same (Experiment 1). Individuals who formulate their chances of achieving a successful outcome in positive terms are supposed to make different decisions than individuals who use equivalent, but negatively formulated, phrases (Experiments 2 and 3). Finally, negative phrases lead to fewer conjunction errors in probabilistic reasoning than do positive phrases (Experiment 4). For instance, a combination of 2 “uncertain” outcomes is readily seen to be “very uncertain.” But positive phrases lead to fewer disjunction errors than do negative phrases. Thus verbal probabilistic phrases differ from numerical probabilities not primarily by being more “vague,” but by suggesting more clearly the kind of inferences that should be drawn.     

Outline of a New Semantics for Counterfactuals

Abstract: It is argued that the so-called principles of "strong centering" and "weak centering" central to the traditional Lewis-Stalnaker semantics for counterfactuals are both fallacious. A foundation for an alternative semantics without these prinsciples is outlined. The core idea is that the statistically normal worlds – rather than those worlds most qualitatively similar to the actual world – should serve as the semantical fulcrum.     

A Bayesian Power Analysis Procedure Considering Uncertainty in Effect Size Estimates from a Meta-analysis

In conventional frequentist power analysis, one often uses an effect size estimate, treats it as if it were the true value, and ignores uncertainty in the effect size estimate for the analysis. The resulting sample sizes can vary dramatically depending on the chosen effect size value. To resolve the problem, we propose a hybrid Bayesian power analysis procedure that models uncertainty in the effect size estimates from a meta-analysis. We use observed effect sizes and prior distributions to obtain the posterior distribution of the effect size and model parameters. Then, we simulate effect sizes from the obtained posterior distribution. For each simulated effect size, we obtain a power value. With an estimated power distribution for a given sample size, we can estimate the probability of reaching a power level or higher and the expected power. With a range of planned sample sizes, we can generate a power assurance curve. Both the conventional frequentist and our Bayesian procedures were applied to conduct prospective power analyses for two meta-analysis examples (testing standardized mean differences in example 1 and Pearson's correlations in example 2). The advantages of our proposed procedure are demonstrated and discussed.     

Buridan's Consequentia: Consequence and Inference Within a Token-Based Semantics

I examine the theory of consequentia of the medieval logician, John Buridan. Buridan advocates a strict commitment to what we now call proposition-tokens as the bearers of truth-value. The analysis of Buridan's theory shows that, within a token-based semantics, amendments to the usual notions of inference and consequence are made necessary, since pragmatic elements disrupt the semantic behaviour of propositions. In my reconstruction of Buridan's theory, I use some of the apparatus of modern two-dimensional semantics, such as two-dimensional matrices and the distinction between the context of formation and the context of evaluation of utterances.     

Multi-valued Semantics: Why and How

According to Suszko’s Thesis, any multi-valued semantics for a logical system can be replaced by an equivalent bivalent one. Moreover: bivalent semantics for families of logics can frequently be developed in a modular way. On the other hand bivalent semantics usually lacks the crucial property of analycity, a property which is guaranteed for the semantics of multi-valued matrices. We show that one can get both modularity and analycity by using the semantic framework of multi-valued non-deterministic matrices. We further show that for using this framework in a constructive way it is best to view “truth-values” as information carriers, or “information-values”.     

Persistence training: a partial reinforcement procedure for reversing learned helplessness and depression

This article examines the relative merits of either partial or continuous (total) success therapy as a device for reversing learned helplessness and depression in humans. College students experienced (a) no treatment followed by either abbreviated (20 trials) or extended (40 trials) continuous success therapy, (b) soluble problems followed by either abbreviated or extended continuous success therapy, (c) insoluble problems followed by either abbreviated or extended continuous success therapy, or (d) insoluble problems followed be either abbreviated or extended partial success therapy. Subsequently, subjects in all eight groups received 40 escape-extinction trials in which aversive tones were not controllable. The results of this experiment indicated that both continuous and partial success schedules were effective in reversing depressed responding (helplessness) induced by prior exposure to insoluble problems. However, only the partial success therapy schedules produced persistent escape responding in extinction. Also, across therapy procedures, extended therapy generated more response persistence in escape extinction than did abbreviated therapy. Theoretical implications of these results are discussed, and a compatible new treatment program, labeled persistence training, is introduced.     

Multivalent Semantics for Vagueness and Presupposition

Both the phenomenon of presupposition and that of vagueness have motivated the use of one form or another of trivalent logic, in which a declarative sentence can not only receive the standard values true (1) and false (0), but also a third, non-standard truth-value which is usually understood as ‘undefined’ (#). The goal of this paper is to propose a multivalent framework which can deal simultaneously with presupposition and vagueness, and, more specifically, capture their projection properties as well as their different roles in language. Now, there is a prima facie simple way of doing this, which simply consists in assimilating the two phenomena, and using an appropriate type of trivalent logic. On this view, we just need a compositional system that deals with the ‘undefined’ truth-value, and does not care about whether the source of undefinedness is ‘presuppositional’ or related to vagueness. I will argue that such a simple solution cannot succeed, and point out a number of desiderata that any successful approach must meet. I will then present and discuss two seven-valued semantics, inspired, respectively, by the Strong Kleene semantics and by supervaluationism, which meet these desiderata.     

Confirmation and reduction: a Bayesian account

Various scientific theories stand in a reductive relation to each other. In a recent article, we have argued that a generalized version of the Nagel-Schaffner model (GNS) is the right account of this relation. In this article, we present a Bayesian analysis of how GNS impacts on confirmation. We formalize the relation between the reducing and the reduced theory before and after the reduction using Bayesian networks, and thereby show that, post-reduction, the two theories are confirmatory of each other. We then ask when a purported reduction should be accepted on epistemic grounds. To do so, we compare the prior and posterior probabilities of the conjunction of both theories before and after the reduction and ask how well each is confirmed by the available evidence.     

In Defense of a Probability Based Semantics for Counterfactuals

In a recent paper Lee Walters criticizes a number of philosophers – including Gundersen – for committing a ‘failure in the argumentative strategy’ when they attempt to amend the standard Lewis semantics for counterfactuals in order to avoid the so‐called principle of Conjunction Conditionalization. In this article we defend a Gundersen‐style probability‐based semantics against Walter's major misgivings: that it is not logically conservative, that it is committed to the Connection Hypothesis, and that it cannot deal satisfactory with irrelevant semi‐factuals.     

Proof-Theoretic Semantics,a Problem with Negation and Prospects for Modality

This paper discusses proof-theoretic semantics, the project of specifying the meanings of the logical constants in terms of rules of inference governing them. I concentrate on Michael Dummett’s and Dag Prawitz’ philosophical motivations and give precise characterisations of the crucial notions of harmony and stability, placed in the context of proving normalisation results in systems of natural deduction. I point out a problem for defining the meaning of negation in this framework and prospects for an account of the meanings of modal operators in terms of rules of inference.     

Semantics and truth relative to a world

This paper argues that relativity of truth to a world plays no significant role in empirical semantic theory, even as it is done in the model-theoretic tradition relying on intensional type theory. Some philosophical views of content provide an important notion of truth at a world, but they do not constrain the empirical domain of semantic theory in a way that makes this notion empirically significant. As an application of this conclusion, this paper shows that a potential motivation for relativism based on the relativity of truth to a world fails.