This essay argues that the main lesson of Lewis Carroll's Regress is that arguments are constitutively presuppositional.

This paper is divided in five sections. Section 11.1 sketches the history of the distinction between speech act with negative content and negated speech act, and gives a general dynamic interpretation for negated speech act. “Downdate semantics” for AGM contraction is introduced in Section 11.2. Relying on semantically interpreted contraction, Section 11.3 develops the dynamic semantics for constative and directive speech acts, and their external negations. The expressive completeness for the formal variants of natural language utterances, none of which is (...) a retraction, has been proved in Section 11.4. The last section gives a laconic answer to the question posed in the title of the paper. (shrink)

Table of Formal and Descriptivists Ontologists (PDF - from Bernard Bolzano to present time) Ontologists of the 19th and 20th Centuries (a selection of critical judgments about some of the greatest philosophers of the recent past) Living Ontologists (a list of authors with an interest in ontology, with synthetic bibliographies).

The nontechnical ability to identify or match argumentative structure seems to be an important reasoning skill. Instruments that have questions designed to measure this skill include major standardized tests for graduate school admission, for example, the United States-Canadian Law School Admission Test (LSAT), the Graduate Record Examinations (GRE), and the Graduate Management Admission Test (GMAT). Writers and reviewers of such tests need an appropriate foundation for developing such questions--they need a proper representation of phenomenological argumentative structure--for legitimacy, and because these (...) tests affect people's lives. This paper attempts to construct an adequate and appropriate representation of such structure, that is, the logical structure that an argument is perceived to have by mature reasoners, albeit ones who are untrained in logic. (shrink)

This paper distinguishes between two types of persuasive force arguments can have in terms of two different connections between arguments and inferences. First, borrowing from Pinto, an arguer's invitation to inference directly persuades an addressee if the addressee performs an inference that the arguer invites. This raises the question of how invited inferences are determined by an invitation to inference. Second, borrowing from Sorenson, an arguer's invitation to inference indirectly persuades an addressee if the addressee performs an inference guided by (...) the argument even though it is uninvited. This raises the question of how an invitation to inference can guide inferences that the arguer does not use the argument to invite. Focusing on belief-inducing inference, the primary aims here are to clarify what is necessary for an addressee's belief-inducing inference to be invited by an argument used as an instrument of persuasion; and to highlight the capacity of arguments to guide such inferences. The paper moves beyond Pinto's discussion by using Boghossian's Taking Condition in service of and in way that illustrates how epistemically bad arguments can rationally persuade addressees of their conclusions. (shrink)

Consider the proposition, "Informal logic is a subdiscipline of philosophy". The best chance of showing this to be true is showing that informal logic is part of logic, which in turn is a part of philosophy. Part 1 is given over to the task of sorting out these connections. If successful, informal logic can indeed be seen as part of philosophy; but there is no question of an exclusive relationship. Part 2 is a critical appraisal of the suggestion that informal (...) logic is applied epistemology. Part 3 examines the claim that informal logic has failed to penetrate into mainstream philosophy, and suggestions for amelioration are considered. (shrink)

The Toulmin diagram layout is very familiar and widely used, particularly in the teaching of critical thinking skills. The conventional box-and-arrow diagram is equally familiar and widespread. Translation between the two throws up a number of interesting challenges. Some of these challenges (such as the relationship between Toulmin warrants and their counterparts in traditional diagrams) represent slightly different ways of looking at old and deep theoretical questions. Others (such as how to allow Toulmin diagrams to be recursive) are diagrammatic versions (...) of questions that have already been addressed in artificial intelligence models of argument. But there are further questions (such as the relationships between refutations, rebuttals and undercutters, and the roles of multiple warrants) that are posed as a specific result of examining the diagram inter-translation problem. These three classes of problems are discussed. To the first class are addressed solutions based on engineering pragmatism; to the second class, are addressed solutions drawn from the appropriate literature; and to the third class, fuller exploration is offered justifying the approaches taken in developing solutions that offer both pragmatic utility and theoretical interest. Finally, these solutions are explored briefly in the context of the Araucaria system, showing the ways in which analysts can tackle arguments either using one diagrammatic style or another, or even a combination of the two. (shrink)

The following article reconstructs Plato’s argument for the existence of god in Laws X. The article starts with interpreting the argument for the priority of soul and continues with a discussion of the argumentation for rationality of the soul in charge of heavens . The view defended here is that Plato first defines the essential characteristics of the divine, namely self-motion and rationality, and then shows that there are entities which possess these characteristics and therefore deserve to be called gods (...) or divine. The article further shows that several sub-arguments mirror the structure of the overall proof. (shrink)

What is informal logic, is it ``logic" at all? Main contemporary approaches are briefly presented and critically commented. If the notion of consequence is at the heart of logic, does it make sense to speak about ``informal" consequence? A valid inference is truth preserving, if the premises are true, so is the conclusion. According to Prawitz two further conditions must also be satisfied in the case of classical logical consequence: (i) it is because of the logical form of the sentences (...) involved and not because of their specific content that the inference is truth preserving; (ii) it is necessary that if the premises are true, then so is the conclusion. According to the prevalent criteria of informal logic an argument is cogent if and only if (i) its premises are rationally Acceptable, (ii) its premises are Relevant to its conclusion and (iii) its premises constitute Grounds adequate for accepting the conclusion (the ``ARG" conditions according to Govier). The ARG criteria characterize a certain broad kind of consequence relation. We do not (in general) have truth preservence in cogent arguments but if the premises are acceptable and other criteria are met, then so is the conclusion. We can speak about form in a loose sense and finally, there is rational necessity of the grounding or support relation. So a certain broad notion of logical consequence emerges from this comparison. The norms of ARG are norms of elementary scientific methodology in which argument is seen as embodying reasoning within a process of inquiry or of belief formation in subject areas accessible to every informed intellectual. (shrink)