Legal Arguments about Plausible Facts and Their Strategic Presentation

Arguments from plausibility, in which an appeal is made to customary behavior, are often used in the legal practice. For example: Joran van derSloot must have murdered Natalee Holloway, otherwise he would have called an ambulance when she looked dead. As in the example, such arguments are often presented with an explicit appeal to an inference license that gives the argument amodus tollensstructure [if he had not murdered her...]. I will address the question what motivates such a presentation

Justification for a Probabilistic Account of Conditionals

In this dissertation I argue that a probabilistic account of conditionals similar to the one proposed by Robert Stalnaker in 1968 is the logical account of conditionals that most aptly models conditional use in natural language. I argue that a probabilistic account of conditionals is best able to account for the most systematic and widespread uses of conditionals in natural language as is evidenced by both its compatibility with the descriptively accurate psychological account, as well as its ability to take into account expert intuitions that diverge from the material conditional interpretation. I provide expert support for Stalnakers account by describing the ways that a probabilistic conditional can avoid the paradoxes of the material conditional. I argue that the predictive accuracy of the alternative mental models account provides support for the claim that Stalnakers logical account of conditionals is descriptively accurate. I conclude that both expert and naive reasoners uses of conditional statements are most accurately modelled by a probabilistic account of conditionals similar to that proposed by Stalnaker

Explicit Conditionals in the Framework of Classical Conditional Logic

The paper proposes a first approach to systems whose language includes two primitives (>+ and >-) as symbols for factual and counterfactual conditionals which are explicit, i.e. that are stated jointly with the truth or falsity of the antecedent clause. In systems based on this language, here called 2-conditional, the standard corner operator may be defined by (Def>) A > B := (A >+ B)∨(A >- B), while in classical conditional systems one could introduce the two symbols for explicit conditionals by the definitions (Def>+) A >+ B := A∧(A>B) and (Def>-) A>- B := ¬A∧(A>B). Two 2-conditional systems, V² and VW², are axiomatized and proved to be definitionally equivalent to the monoconditional systems V and VW. A third system VWTr² is characterized by an axiom stating the transitivity of factual conditionals and is shown to be distinct from V², from VW² and from the 2-conditional version of Lewis’ well-known system VC, here named VC². The same may be said for a fourth system VW²◊ ±, based on an axiom inderivable in VC²: ◊(A >+ B) ⊃ ◊( ¬A >- ¬B). VC² contains what is here called a “semi-collapse” of the operator >+ and it is argued that it is inadequate as a logic for both factual and counterfactual conditionals. The last section shows that several different definitions of the corner operators in terms of >+ and >- may be introduced as an alternative to (Def>)

Reasoning with conditionals

This paper reviews the psychological investigation of reasoning with conditionals, putting an emphasis on recent work. In the first part, a few methodological remarks are presented. In the second part, the main theories of deductive reasoning (mental rules, mental models, and the probabilistic approach) are considered in turn; their content is summarised and the semantics they assume for if and the way they explain formal conditional reasoning are discussed, in particular in the light of experimental work on the probability of conditionals. The last part presents the recent shift of interest towards the study of conditional reasoning in context, that is, with large knowledge bases and uncertain premises

Machine ethics via logic programming

Machine ethics is an interdisciplinary field of inquiry that emerges from the need of imbuing autonomous agents with the capacity of moral decision-making. While some approaches provide implementations in Logic Programming (LP) systems, they have not exploited LP-based reasoning features that appear essential for moral reasoning. This PhD thesis aims at investigating further the appropriateness of LP, notably a combination of LP-based reasoning features, including techniques available in LP systems, to machine ethics. Moral facets, as studied in moral philosophy and psychology, that are amenable to computational modeling are identified, and mapped to appropriate LP concepts for representing and reasoning about them. The main contributions of the thesis are twofold. First, novel approaches are proposed for employing tabling in contextual abduction and updating – individually and combined – plus a LP approach of counterfactual reasoning; the latter being implemented on top of the aforementioned combined abduction and updating technique with tabling. They are all important to model various issues of the aforementioned moral facets. Second, a variety of LP-based reasoning features are applied to model the identified moral facets, through moral examples taken off-the-shelf from the morality literature. These applications include: (1) Modeling moral permissibility according to the Doctrines of Double Effect (DDE) and Triple Effect (DTE), demonstrating deontological and utilitarian judgments via integrity constraints (in abduction) and preferences over abductive scenarios; (2) Modeling moral reasoning under uncertainty of actions, via abduction and probabilistic LP; (3) Modeling moral updating (that allows other – possibly overriding – moral rules to be adopted by an agent, on top of those it currently follows) via the integration of tabling in contextual abduction and updating; and (4) Modeling moral permissibility and its justification via counterfactuals, where counterfactuals are used for formulating DDE.Fundação para a Ciência e a Tecnologia (FCT)-grant SFRH/BD/72795/2010 ; CENTRIA and DI/FCT/UNL for the supplementary fundin

Modalizing: A Function-Driven Approach

This thesis is about modals: words like ‘possible’ and ‘necessary’, ‘must’ and ‘can’. More specifically, it is about their roles in our lives. More specifically still, I want to approach, via the issue of modal function, the relationship between what I call ordinary and philosophical modalizing: the modalizing that we learn in the wild, and the modalizing that we learn in the philosophy classroom. What are the commonalities between these activities? What are their differences? In order to focus and dramatize the issue, I begin by introducing a figure whom I call the Ascetic Modalizer. The Ascetic Modalizer insists against there being theoretically significant continuities between the modals that we ordinarily use to talk about powers and dispositions, and the modals that some philosophers have called absolute. After arguing that modal semantics, metaphysics, and epistemology may prove too slow a route towards progress in this debate, I suggest that we approach the matter via the neglected topic of modal function. To get clear on modal function, however, one must first get clear on conditionals. I therefore argue for some novel assertability conditions for subjunctive conditionals, which are informed by the functions of these important constructions. In the process, I shed some light on the differences between kinds of supposition. This discussion of conditionals and suppositions then allows me to draw together two different research programmes in the theory of modal function. With those resources in hand, I investigate the roles of some ordinary and philosophical modals in our practical and theoretical deliberations. I argue that in so far as those functions are concerned, the Ascetic Modalizer may be right to be sceptical of modal unification. Finally, I show how the preceding discussion intersects with two ancient ideas about modality: that deductive validity requires necessary truth-preservation, and that necessity implies actuality

The Teleological and Kalam Cosmological Arguments Revisited

A prominent issue in many contemporary philosophy of religion debates concerns whether the universe has a Designer. This book moves the discussion ahead in a significant way by devising an original deductive formulation of the Teleological Argument (TA) which demonstrates that the following are the only possible categories of hypotheses concerning fine-tuning and order: (i) chance, (ii) regularity, (iii) combinations of regularity and chance, (iv) uncaused, and (v) design. This book also demonstrates that there are essential features of each category such that, while the alternatives to design are unlikely, the Design Hypothesis is not, and that one can argue for design by exclusion without having to first assign a prior probability for design. By combining the TA with the Kalam Cosmological Argument (KCA) which it defends against various objections, this book responds to the God-of-the-gaps objection by demonstrating that the conclusion of the KCA-TA is not based on gaps which can be filled by further scientific progress, but follows from deduction and exclusion. This is an open access book

Hvad er formålet med generiske og generaliserende ytringer i løbende tekst?

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