Claims that necessary and sufficient conditions are not converse relations are discussed, as well as the related claim that If A, then B is not equivalent to A only if B . The analysis of alleged counterexamples has shown, among other things, how necessary and sufficient conditions should be understood, especially in the case of causal conditions, and the importance of distinguishing sufficient-cause conditionals from necessary-cause conditionals. It is concluded that necessary and sufficient conditions, adequately interpreted, are converse relations in (...) all cases. (shrink)

This paper explores the question of what makes diagrammatic representations effective for human logical reasoning, focusing on how Euler diagrams support syllogistic reasoning. It is widely held that diagrammatic representations aid intuitive understanding of logical reasoning. In the psychological literature, however, it is still controversial whether and how Euler diagrams can aid untrained people to successfully conduct logical reasoning such as set-theoretic and syllogistic reasoning. To challenge the negative view, we build on the findings of modern diagrammatic logic and introduce (...) an Euler-style diagrammatic representation system that is designed to avoid problems inherent to a traditional version of Euler diagrams. It is hypothesized that Euler diagrams are effective not only in interpreting sentential premises but also in reasoning about semantic structures implicit in given sentences. To test the hypothesis, we compared Euler diagrams with other types of diagrams having different syntactic or semantic properties. Experiment compared the difference in performance between syllogistic reasoning with Euler diagrams and Venn diagrams. Additional analysis examined the case of a linear variant of Euler diagrams, in which set-relationships are represented by one-dimensional lines. The experimental results provide evidence supporting our hypothesis. It is argued that the efficacy of diagrams in supporting syllogistic reasoning crucially depends on the way they represent the relational information contained in categorical sentences. (shrink)

I give an account of the compositional semantics of unconditionals that explains their relationship to if -conditionals in the Lewis/Kratzer/Heim tradition. Unconditionals involve an alternative-denoting adjunct that supplies domain restrictions pointwise to a main-clause operator such as a modal. The differences from if -clauses follow from the structure of the adjuncts; both are conditionals in the Lewisian sense. In the course of treating unconditionals, I provide a concrete implementation of conditionals where conditional adjuncts in general are a species of correlative, (...) and show what detaching this hypothesis from if involves. (shrink)

In this paper I am concerned with the analysis of fragments of a discourse or text that express arguments suspected of being denials of the antecedent. I first argue that one needs to distinguish between two senses of ‘the argument expressed’. Second, I show that, with respect to one of these senses, given a Gricean account of the pragmatics of conditionals, some such fragments systematically express arguments that are valid.

Pfeifer defiende que los seres humanos no interpretan los enunciados condicionales como condicionales materiales, sino como eventos condicionales. Para probarlo, plantea dos experimentos basados en la tesis de Aristóteles y, a partir de los resultados que obtiene, argumenta que es obvio que sus participantes entendieron los enunciados condicionales que se les presentaron como eventos condicionales. No obstante, si tenemos en cuenta el fenómeno de la perfección del condicional y que los enunciados condicionales pueden ser interpretados como bicondicionales, se puede pensar (...) en una explicación alternativa para los resultados de Pfeifer sin necesidad de admitir su tesis relativa a que los enunciados condicionales se interpretan como eventos condicionales. En este trabajo, tratamos de demostrarlo. Pfeifer holds that human beings do not interpret conditional statements as material conditionals, but as conditional events. To demonstrate it, he presents two experiments based on Aristotle´s thesis and, from the outcomes he obtained, he argues that it is obvious that his participants understood the conditional statements that were presented as conditional events. However, if we consider that conditional perfection phenomenon and conditional statements can be interpreted as biconditional statements, we can think of an alternative explanation for Pfeifer´s outcomes without admitting his thesis, namely, that conditional statements are interpreted as conditional events. In this paper, I try to prove that. (shrink)

There is an Aristotelian thesis that can be considered controversial. That is the thesis related to a denied conditional with only one propositional variable and in which, in addition, one of its clauses is also denied. While the thesis is not a tautology, people tend to accept it as true. Pfeifer’s approach can account for this fact. However, I try to show that this problem can also be explained from other alternative frameworks, in particular, from that of the mental models (...) theory, that of López-Astorga based on the pragmatic phenomenon of conditional perfection, and that of the mental logic theory. Likewise, I indicate the difficulties regarding Aristotle’s thesis of the mental models theory and López-Astorga’s proposal, and conclude that the account of the mental logic theory is the strongest alternative to Pfeifer’s explanation and that what is clearly obvious is that conditional should not be materially interpreted. (shrink)

Skeptical puzzles and arguments often employ knowledge-closure principles . Epistemologists widely believe that an adequate reply to the skeptic should explain why her reasoning is appealing albeit misleading; but it’s unclear what would explain the appeal of the skeptic’s closure principle, if not for its truth. In this paper, I aim to challenge the widespread commitment to knowledge-closure. But I proceed by first examining a new puzzle about failing to know—what I call the New Ignorance Puzzle . This puzzle resembles (...) to the Old Ignorance Puzzle , although it does not involve a closure principle. It instead centers on the standard view of ignorance, a highly intuitive principle stating that ignorance is merely a failure to know. In Sects. 2 and 3, I argue that the best way to solve the New Ignorance Puzzle is to reject the standard view of ignorance and to explain away its appeal via conversational implicature. I then use this solution to the New Ignorance Puzzle as a way of explaining why knowledge-closure principles would seem true, and why abominable conjunctions would seem abominable, even if such principles were false . The upshot is a new way of explaining why the skeptic’s reasoning is appealing albeit misleading. (shrink)

Scalar implicatures depend on alternatives in order to avoid the symmetry problem. I argue for a structure-sensitive characterization of these alternatives: the alternatives for a structure are all those structures that are at most as complex as the original one. There have been claims in the literature that complexity is irrelevant for implicatures and that the relevant condition is the semantic notion of monotonicity. I provide new data that pose a challenge to the use of monotonicity and that support the (...) structure-sensitive definition. I show that what appeared to be a problem for the complexity approach is overcome once an appropriate notion of complexity is adopted, and that upon closer inspection, the argument in favor of monotonicity turns out to be an argument against it and in favor of the complexity approach. (shrink)

We revisit a typological puzzle due to Horn (Doctoral Dissertation, UCLA, 1972) regarding the lexicalization of logical operators: in instantiations of the traditional square of opposition across categories and languages, the O corner, corresponding to ‘nand’ (= not and), ‘nevery’ (= not every), etc., is never lexicalized. We discuss Horn’s proposal, which involves the interaction of two economy conditions, one that relies on scalar implicatures and one that relies on markedness. We observe that in order to express markedness and to (...) account for a bigger typological puzzle, namely the absence of lexicalizations of ‘XOR’ (= exclusive or), ‘all-or-none’, and many other imaginable logical operators, one must restrict the basic lexicalizable elements to a small set of primitives. We suggest that an ordering based perspective, following Keenan and Faltz (Boolean semantics for natural language, 1985), makes the stipulated primitives that we arrive at more natural. We also propose a modification to Horn’s proposal, based on recent work on implicatures, in which only the implicature condition is operative and in which markedness is part of the definition of the alternatives for scalar implicatures rather than an independent condition. (shrink)

This paper explores the relationship between dynamic and truth conditional semantics for epistemic modals. It provides a generalization of a standard dynamic update semantics for modals. This new semantics derives a Kripke semantics for modals and a standard dynamic semantics for modals as special cases. The semantics allows for new characterizations of a variety of principles in modal logic, including the inconsistency of ‘p and might not p’. Finally, the semantics provides a construction procedure for transforming any truth conditional semantics (...) for modals into a dynamic semantics for modals with similar properties. (shrink)

Recent work on conditional reasoning argues that denying the antecedent [DA] and affirming the consequent [AC] are defeasible but cogent patterns of argument, either because they are effective, rational, albeit heuristic applications of Bayesian probability, or because they are licensed by the principle of total evidence. Against this, we show that on any prevailing interpretation of indicative conditionals the premises of DA and AC arguments do not license their conclusions without additional assumptions. The cogency of DA and AC inferences rather (...) depends on contingent factors extrinsic to, and independent of, what is asserted by DA and AC arguments. arguments do not license their conclusions without additional assumptions. The cogency of DA and AC inferences rather depends on contingent factors extrinsic to, and independent of, what is asserted by DA and AC arguments. (shrink)

I explain what exactly constrains presupposition projection in compound sentences and argue that the presuppositions that do not project are conditionalized, giving rise to inferable conditional presuppositions. I combine elements of and which, together with an additional, independently motivated assumption, make it possible to construct an analysis that makes correct predictions. The core of my proposal is as follows: When a speaker felicitously utters a compound sentence whose constituent clauses require presuppositions, the hearer will infer that the speaker presupposes those (...) propositions, unless the sentence contains some element that makes the hearer realize that, if the speaker actually presupposed them, she would be either uninformative or inconsistent in her beliefs. In these cases, the propositions that would have been presupposed, had the clauses been uttered in isolation, will not be presupposed, i.e. the clausal presuppositions will not project. (shrink)

This paper presents a unified, more-or-less complete, and largely pragmatic theory of indicative conditionals as they occur in natural language, which is entirely truth-functional and does not involve probability. It includes material implication as a special—and the most important—case, but not as the only case. The theory of conditional elements, as we term it, treats if-statements analogously to the more familiar and less controversial other truth-functional compounds, such as conjunction and disjunction.

We present an argument for revising the theory of alternatives for Scalar Implicatures and for Association with Focus. We argue that in both cases the alternatives are determined in the same way, as a contextual restriction of the focus value of the sentence, which, in turn, is defined in structure-sensitive terms. We provide evidence that contextual restriction is subject to a constraint that prevents it from discriminating between alternatives when they stand in a particular logical relationship with the assertion or (...) the prejacent, a relationship that we refer to as symmetry. Due to this constraint on contextual restriction, discriminating between alternatives in cases of symmetry becomes the task of focus values. This conclusion is incompatible with standard type-theoretic definitions of focus values, motivating our structure-sensitive definition instead. (shrink)

Modus ponens is the argument from premises of the form If A, then B and A to the conclusion B. Nearly all participants agree that the modus ponens conclusion logically follows when the argument appears in this Basic form. However, adding a further premise can lower participants’ rate of agreement—an effect called suppression. We propose a theory of suppression that draws on contemporary ideas about conditional sentences in linguistics and philosophy. Semantically, the theory assumes that people interpret an indicative conditional (...) as a context-sensitive strict conditional: true if and only if its consequent is true in each of a contextually determined set of situations in which its antecedent is true. Pragmatically, the theory claims that context changes in response to new assertions, including new conditional premises. Thus, the conclusion of a modus ponens argument may no longer be accepted in the changed context. Psychologically, the theory describes people as capable of reasoning about broad classes of possible situations, ordered by typicality, without having to reason about individual possible worlds. The theory accounts for the main suppression phenomena, and it generates some novel predictions that new experiments confirm. (shrink)

Stoic logic assumes five inference schemata attributed to Chrysippus of Soli. Those schemata are the well-known indemonstrables. A problem related to them can be that, according to standard propositional calculus, only one of them, modus ponens, is clearly indemonstrable. Nevertheless, I try to show in this paper that the mental logic theory enables to understand why the Stoics considered such schemata to be basic kinds of arguments. Following that theory, four of them can be linked to ‘Core Schemata’ of mental (...) logic and the only one that is more controversial is modus tollens. However, as I also comment, some assumptions of Stoic philosophy, which can be interpreted from the mental logic theory, can explain why this last argument was included into the set of the indemonstrablesas well. (shrink)

Evolutionary psychology—in its ambitious version well formulated by Cosmides and Tooby (e.g., Cosmides & Tooby 1987, Tooby & Cosmides 1992) —will succeed to the extent that it causes cognitive psychologists to rethink central aspects of human cognition in an evolutionary perspective, to the extent, that is, that psychology in general becomes evolutionary. The human species is exceptional by its massive investment in cognition, and in forms of cognitive activity—language, metarepresentation, abstract thinking—that are as unique to humans as echolocation is unique (...) to bats. The promise of evolutionary psychology is thus to help explain not just traits of human psychology that are homologous to those of many other species, but also traits of human psychology that are genuinely exceptional and that in turn help explain the exceptional character of human culture and ecology. However, most of the work done in evolutionary psychology so far is on aspects of human psychology that are not specifically human except in their details. Showing, for instance, how human preferences in mate choice are fine -tuned in the way the theory of evolution would predict is of great interest (see e.g., Buss 1994) but it can be done on the basis of a relatively shallow psychology. This makes work on distinctly human adaptations involving higher cognition of particular importance for defenders of a psychologically ambitious evolutionary psychology. What is often presented (e.g., Pinker, 1997) as the signal achievement of cognitive evolutionary psychology in this respect is the experimental testing of Cosmides’ (1989) hypothesis that there exists an evolved competence to deal with social contracts, and, in particular to detect cheaters. We want to argue that, because of faulty methodological choices—the quasi-exclusive reliance on the four-cards selection task—, the hypothesis has in fact not yet been tested. The plan of this chapter is as follows: We begin, with a short presentation of Cosmides’s social contract hypothesis, of Wason selection task, and of Cosmides’s reasons to use the task in order to test the theory.. (shrink)

Arguments are movements of thought. From a logical point of view, such a movement is justifiable as it tends to preserve or transmit truth. To speak of such tendency is to abstract from particular movements of thought and to ascent to the forms of such movements. Thus logical theory is said to concern rules of validity or cogency that one may use to evaluate forms of arguments, forms as may be instantiated by particular sets of statements which we may use (...) to represent particular movements of thought. (shrink)

In the first part of this paper I make some general remarks about the relevance of semantics and pragmatics to argumentation theory, insisting on the importance of the reconstruction of speaker meaning for argument analysis, especially in the case of implicatures. In the second part of the paper I look more closely at the relation between argument and implicature. In the last part I discuss the concept of argumentative implicature, that is, implicatures that are generated by speech acts of arguing. (...) I maintain, against Jackson (1987), that there are no specifically argumentative implicatures. (shrink)

Attridge and Inglis try to check whether or not the ‘Theory of Formal Discipline’ is correct. This theory states that learning mathematics improves logical reasoning, and Attridge and Inglis review it by means of an experiment. Their conclusion is that, indeed, learning mathematics improves conditional inferences causing that conditionals are interpreted as defective. In this paper, I analyze Attridge and Inglis´s experiment and hold that it has a methodological problem and that hence does not really prove that learning mathematics lead (...) to defective interpretations of conditionals. Equally, the paper includes a brief reflection on how the mental models theory can explain the results achieved by Attridge and Inglis. (shrink)

Conditional perfection is the phenomenon in which conditionals are strengthened to biconditionals. In some contexts, “If A, B” is understood as if it meant “A if and only if B.” We present and discuss a series of experiments designed to test one of the most promising pragmatic accounts of conditional perfection. This is the idea that conditional perfection is a form of exhaustification—that is a strengthening to an exhaustive reading, triggered by a question that the conditional answers. If a speaker (...) is asked how B comes about, then the answer “If A, B” is interpreted exhaustively to meaning that A is the only way to bring about B. Hence, “A if and only if B.” We uncover evidence that conditional perfection is a form of exhaustification, but not that it is triggered by a relationship to a salient question. (shrink)

It has been argued that a fragment of discourse that constitutes a fallacy of denying the antecedent at the level of what is literally said may not be a fallacy at the level of speaker meaning. The pragmatic phenomenon involved here is known as conditional perfection. I argue that the account of conditional perfection in van der Auwera and Horn has several problems, and I discuss several possible alternatives.