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.

Routley?s Formula says, for instance, that if it is believed there is a man then there is something which is believed to be a man. In this paper I defend the formula; first directly, but then by looking at work by Gensler and Hintikka against it, and at the original work of Routley, Meyer and Goddard for it. The argument ultimately reduces to a central point about the extensionality of objects in Routley, Meyer and Goddard?s intensional system, i.e. in its (...) formulation of transparency. (shrink)

Two types of logical consequence are compared: one, with respect to matrix and designated elements and the other with respect to ordering in a suitable algebraic structure. Particular emphasis is laid on algebraic structures in which there is no top-element relative to the ordering. The significance of this special condition is discussed. Sequent calculi for a number of such structures are developed. As a consequence it is re-established that the notion of truth as such, not to speak of tautologies, is (...) inessential in order to define validity of an argument. (shrink)

The object of this paper is to show why recent research in the psychology of deductive and probabilistic reasoning does not have.

En este estudio analizamos dos tendencias claramente distintas y contrapuestas en la forma de impartir cursos elementales de Lógica en la formación superior. Para este propósito, se ha seleccionado una muestra de manuales angloamericanos clásicos, así como otra más pequeña de la tradición iberoamericana para comprobar nuestras hipótesis. Los estilos identificados y analizados en dichos manuales son lo que hemos denominado lógica matemática y lógica para filósofos. En ambos casos se trata de tendencias muy generales reconocibles en las más diversas (...) tradiciones locales. El periodo analizado, 1940-1980, responde al proceso de introducción de la Lógica contemporánea en el ámbito académico occidental. (shrink)

Composition as Identity is the view that an object is identical to its parts taken collectively. I elaborate and defend a theory based on this idea: composition is a kind of identity. Since this claim is best presented within a plural logic, I develop a formal system of plural logic. The principles of this system differ from the standard views on plural logic because one of my central claims is that identity is a relation which comes in a variety of (...) forms and only one of them obeys substitution unrestrictedly. I justify this departure from orthodoxy by showing some problems which result from attempts to avoid inconsistencies within plural logic by means of postulating other non-singular terms besides plural terms. Thereby, some of the main criticisms raised against Composition as Identity can be addressed. Further, I argue that the way objects are arranged is relevant with respect to the question which object they compose, i.e. to which object they are identical to. This helps to meet a second group of arguments against Composition as Identity. These arguments aim to show that identifying composite objects on the basis of the identity of their parts entails, contrary to our common sense view, that rearranging the parts of a composite object does not leave us with a different object. Moreover, it allows us to carve out the intensional aspects of Composition as Identity and to defend mereological universalism, the claim that any objects compose some object. Much of the pressure put on the latter view can be avoided by distinguishing the question whether some objects compose an object from the question what object they compose. Eventually, I conclude that Composition as Identity is a coherent and plausible position, as long as we take identity to be a more complex relation than commonly assumed. (shrink)

This is a review of Vicious Circles: On the Mathematics of Non-Wellfounded Phenomena, written by Jon Barwise and Lawrence Moss and published by CSLI Publications in 1996.

This work studies manipulative use of language that can be called “deliberate failure of communication”; I characterize this kind of manipulation and show that it can be found in the discourse of marketing experts and legal professionals. Relying on relevance theory, I show that manipulation of this kind takes advantage of what van Dijk calls the “context model” of the addressees. I exemplify two ways in which the context models of some of the discourse’s participants might be misused in order (...) to manipulate them. One way is exemplified by a text from an advertisement, the other by a text from a criminal court file. I propose, finally, that the analysis supports van Dijk’s view that social, discursive, and epistemic inequalities reproduce one another in a kind of vicious circle. It suggests, in van Dijk’s terms, that manipulation by deliberate failure of communication is a discriminatory use of language employed by elite groups in order to reproduce their social power. (shrink)

The paper aims to provide an analysis and critique of Carl Wellman’s account of conduction presented in Challenge and Response and Morals and Ethics. It considers several issues, including: reason-ing vs. argument, the definition vs. the three patterns of conduction, pro and con arguments as dialogues, their assessment, the concept of validity, applications beyond moral arguments, argument type vs. as crite-rion of evaluation.

This paper presents an axiomatic formalization of a theory of top-level relations between three categories of entities: individuals, universals, and collections. We deal with a variety of relations between entities in these categories, including the sub-universal relation among universals and the parthood relation among individuals, as well as cross-categorial relations such as instantiation and membership. We show that an adequate understanding of the formal properties of such relations – in particular their behavior with respect to time – is critical for (...) geographic information processing. The axiomatic theory is developed using Isabelle, a computational system for implementing logical formalisms. All proofs are computer verified and the computational representation of the theory is available online. (shrink)

To prove the equivalence one must start with one side, and the earlier-later side seems, for starting with, logically the clearer. The equivalence is provable on reasonable definitions of ‘past’, ‘present’ and ‘future’ in terms of the earlier-later structure of time. McTaggart's attempted distinction between the past-present-future A series and the earlier-later B series, as though they were rivals for the structure of time, is based on an unexamined, and false, assumption. The equivalence shows they are not rivals; they are (...) quite consistent with each other. A very serious consequence is that all subsequent argument, from the A side or the B, however sophisticated, is flawed to the extent that it accepts McTaggart's false distinction. (shrink)

In this paper, I investigate whether we can use a world-involving framework to model the epistemic states of non-ideal agents. The standard possible-world framework falters in this respect because of a commitment to logical omniscience. A familiar attempt to overcome this problem centers around the use of impossible worlds where the truths of logic can be false. As we shall see, if we admit impossible worlds where “anything goes” in modal space, it is easy to model extremely non-ideal agents that (...) are incapable of performing even the most elementary logical deductions. A much harder, and considerably less investigated challenge is to ensure that the resulting modal space can also be used to model moderately ideal agents that are not logically omniscient but nevertheless logically competent. Intuitively, while such agents may fail to rule out subtly impossible worlds that verify complex logical falsehoods, they are nevertheless able to rule out blatantly impossible worlds that verify obvious logical falsehoods. To model moderately ideal agents, I argue, the job is to construct a modal space that contains only possible and non-trivially impossible worlds where it is not the case that “anything goes”. But I prove that it is impossible to develop an impossible-world framework that can do this job and that satisfies certain standard conditions. Effectively, I show that attempts to model moderately ideal agents in a world-involving framework collapse to modeling either logical omniscient agents, or extremely non-ideal agents. (shrink)

Natural deduction is the type of logic most familiar to current philosophers, and indeed is all that many modern philosophers know about logic. Yet natural deduction is a fairly recent innovation in logic, dating from Gentzen and Jaśkowski in 1934. This article traces the development of natural deduction from the view that these founders embraced to the widespread acceptance of the method in the 1960s. I focus especially on the different choices made by writers of elementary textbooks—the standard conduits of (...) the method to a generation of philosophers—with an eye to determining what the ‘essential characteristics’ of natural deduction are. (shrink)

In this paper, we will explore two initiatives that focus on the importance of employing logical theories in educating people how to think and reason properly, one in Poland: The Lvov-Warsaw School; the other in North America: The Informal Logic Initiative. These two movements differ in the logical means and skills that they focus on. However, we believe that they share a common purpose: to educate students in logic and reasoning (logical education conceived as a process) so that they may (...) be able to apply their skills to analyze the issues in their society (logical culture as a result of logical education). The aim of the paper is to justify this claim by exploring research objectives and products that are common to both movements. (shrink)

I will suggest, in this article, a possible explanation of the fact that legal language appears incoherent to the general public. I will present one legal text (an indictment), explaining why it appears incoherent to legal laypersons. I will argue that the traits making this particular text appear incoherent are, first, that a specialized legal meaning is conveyed implicitly and, second, that there are no key-words that could direct laypersons to the knowledge making this meaning obvious to legalists. I will (...) conclude that any legal text having these traits is likely to appear incoherent to the general public and suggest that the traits making my example appear incoherent might be rather common among the various texts of the various legal systems. On this suggestion there is no need to assume any causal relation between lawyers’ social interests and the apparent incoherence of legal language as it entails that this incoherence is inevitable. (I will argue that it is a result of the facts that legal language is ordinary language used, in the ordinary way, in the special context of the legal discourse.). (shrink)

The rhetoric-analytic critique of experimental psychology owes its apparent attractiveness to (a) some erroneous ideas about cognitive psychology and the rationale of experimentation, (b) the failure to distinguish between prior data and evidential data vis-à-vis the to-be-corroborated explanatory theory, and (c) evidential data owes their identity to a theory that is independent of the theory being tested. Theories in cognitive psychology are accepted because they can withstand concerted efforts to falsify them.