We discuss five kinds of representations of rationales and provide a formal account of how they can alter disputation. The formal model of disputation is derived from recent work in argument. The five kinds of rationales are compilation rationales, which can be represented without assuming domain-knowledge (such as utilities) beyond that normally required for argument. The principal thesis is that such rationales can be analyzed in a framework of argument not too different from what AI already has. The result is (...) a formal understanding of rationales, a partial taxonomy, and a foundation for computer programs that represent and reason with rationales.The five kinds of rationales are as follows: (c)ompression and (s)pecialization, which yield rules, and (d)isputation, which yields a decision. These are modeled as potentially changing the focus of the dispute. Then there are (f)it, a rationale for rules, and (r)esolution, a rationale for decisions. These cannot be modeled as simply; they force disputation to a meta-level, at least temporarily. (shrink)

Lilian Bermejo-Luque has posed these questions:1.What is the relationship between presumption and presumptive inference? 2.What are the correctness conditions for presumptions and presumptive inferences? Cohen’s method of relevant variables, Toulmin’s model, and Rescher’s theory of plausibility suggest answers. An inference is presumptive just in case its warrant transfers presumption from its premises to its conclusion. A warrant licencing an inference from the claim that an empirical property φ holds to the claim that some other property ψ holds is backed by (...) observation of a constant conjunction of those properties. The stronger the backing, the stronger the warrant. Warrants may be defeated by instances of φ holding in conjunction with some property χ and ψ not holding. The method of relevant variables directs us to organize such defeating properties into relevant variables. We then test the strength of a warrant by seeing how many variables fail to have a value which defeats the warrant. The more variables with no defeater, the stronger the warrant. We may construct a canonical ordering of the relevant variables by ranking them according to the plausibility of their including defeating values. We may evaluate the strength not only of empirically backed warrants, but warrants backed by institutional rules, such as a branch of law, or by a priori intuited connections between properties. An inference rule will be presumptive just in case the plausibility of its warrant being defeated is below some specified level. (shrink)

Standards and norms for reasoning function, in part, to manage epistemic risk. Properly used, modal qualifiers like presumably have a role in systematically managing epistemic risk by flagging and tracking type-specific epistemic merits and risks of the claims they modify. Yet, argumentation-theoretic accounts of presumption often define it in terms of modalities of other kinds, thereby failing to recognize the unique risk profile of each. This paper offers a stipulative account of presumption, inspired by Ullmann-Margalit, as an inferentially generated modal (...) qualifier, “presumably, p,” distinguishing it from other, particularly epistemic modalities, e.g., standing commitments, assumptions, assertions, suppositions, hypotheses, and defeasible claims. By avoiding the tranching of inferential instruments of qualitatively different bona fides and risk profiles, this account provides a more accurate risk-rating system that better manages epistemic risk in inference, as well as contributing to the normative theory of the operation of presumption in reasoning and argument. (shrink)

This paper is an exercise in intellectual history, an attempt to understand how a specific term—”informal logic”— came to be interpreted in so many different ways. I trace the emergence and development of “informal logic” to help explain the many different meanings, how they emerged and how they are related. This paper is also, to some degree, an account of a movement that developed outside the mainstream of philosophy, whose origins lie in a desire to make logic useful (echoing Dewey).

ABSTRACT Inspired by legal reasoning, this paper presents a semantics and proof theory of a system for defeasible argumentation. Arguments are expressed in a logic-programming language with both weak and strong negation, conflicts between arguments are decided with the help of priorities on the rules. An important feature of the system is that these priorities are not fixed, but are themselves defeasibly derived as conclusions within the system. Thus debates on the choice between conflicting arguments can also be modelled. The (...) semantics of the system is given with a fixpoint definition, while its proof theory is stated in dialectical style, where a proof takes the form of a dialogue between a proponent and an opponent of an argument: an argument is shown to be justified if the proponent can make the opponent run out of moves in whatever way the opponent attacks. (shrink)

An approach to argument macrostructure -- The dialectical nature of argument -- Toulmin's problematic notion of warrant -- The linked-convergent distinction, a first approximation -- Argument structure and disciplinary perspective : the linked-convergent versus multiple-co-ordinatively compound distinctions -- The linked-convergent distinction, refining the criterion -- Argument structure and enthymemes -- From analysis to evaluation.

In this paper we will analyse the issue of defeasibility in the law, taking into account research carried out in philosophy, artificial intelligence and legal theory. We will adopt a very general idea of legal defeasibility, in which we will include all different ways in which certain legal conclusions may need to be abandoned, though no mistake was made in deriving them. We will argue that defeasibility in the law involves three different aspects, which we will call inference‐based defeasibility, process‐based (...) defeasibility, and theory‐based defeasibility. Only the integration of these three perspectives allows us to provide a satisfactory account of the role of defeasibility in legal reasoning. (shrink)

In this paper I investigate the similarities betweenthe dialectical procedure in the pragma-dialecticaltheory and dialectical procedures in AI and Law. I dothis by focusing on one specific type of reasoning inlaw: analogy argumentation. I will argue that analogyargumentation is not only a heuristic forfinding new premises, but also a part of thejustification of legal decisions. The relevantcriteria for the evaluation of analogy argumentationare not to be found at the logical level of inference,but at the procedural level of the discussion. I (...) willproceed as follows. I start with an outline ofPrakken's theory of argumentation frameworks andprocedural models. Then, I will discuss Peczenik'sanalysis of analogy argumentation and try to combineit with the descriptive-normative research ofMacCormick and Summers. Finally, I propose asystematization of the criteria for the evaluation ofanalogy argumentation within the framework of apragma-dialectical notion of an argumentation scheme. (shrink)

The Pleadings Game is a normative formalization and computational model of civil pleading, founded in Roberty Alexy''s discourse theory of legal argumentation. The consequences of arguments and counterarguments are modelled using Geffner and Pearl''s nonmonotonic logic,conditional entailment. Discourse in focussed using the concepts of issue and relevance. Conflicts between arguments can be resolved by arguing about the validity and priority of rules, at any level. The computational model is fully implemented and has been tested using examples from Article Nine of (...) the Uniform Commercial Code. (shrink)

In Part 1 of this wide-ranging interview Heikki Patomäki discusses his early work and career up to the Global Financial Crisis. He provides comment on his role as a public intellectual and activist, his diverse academic interests and influences, and the many and varied ways he has contributed to critical realism and critical realism has influenced his work. In Part 2 he discusses his later work, the predicament of humanity and the role of futures studies.

This volume contains 12 papers addressed to researchers and advanced students in informal logic and related fields, such as argumentation, formal logic, and communications. Among the issues discussed are attempts to rethink the nature of argument and of inference, the role of dialectical context, and the standards for evaluating inferences, and to shed light on the interfaces between informal logic and argumentation theory, rhetoric, formal logic and cognitive psychology.

This volume focuses on dialogue and argumentation in contexts which are marked by truculence and discord. The contributors include well known argumentation scholars who discuss the issues this raises from the point of view of a variety of disciplines and points of view. The authors seek to address theoretically challenging issues in a way that is relevant to both the theory and the practice of argument. The collection brings together selected essays from the 2006 11th Wake Forest University Biennial Argumentation (...) Conference held at Florida Atlantic University in Boca Raton, Florida and the 2012 14th Wake Forest University Biennial Argumentation Conference held at Casa Artom in Venice, Italy. (shrink)

Are there any logical norms for argument evaluation besides soundness and inductive strength? The paper will look at several concepts or models introduced over the years, including those of Wisdom, Toulmin, Wellman, Rescher, defeasible reasoning proponents and Walton to consider whether there is common ground among them that supplies an alternative to deductive validity and inductive strength.

lt is now commonplace in fallacy inquiry for many of the traditional informal fallacies to be viewed as reasonable or nonfallacious modes of argument. Central to this evaluative shift has been the attempt to examine traditional fallacies within their wider contexts of use. However, this pragmatic turn in fallacy evaluation is still in its infancy. The true potential of a contextual approach in the evaluation of the fallacies is yet to be explored. I examine how, in the context of scientific (...) inquiry, certain traditional fallacies function by conferring epistemic gains upon inquiry. Specifically, I argue that these fallacies facilitate the progression of inquiry, particularly in the initial stages ofinquiry when the epistemic context is one of uncertainty. The conception of these fallacies that emerges is that of heuristics of reasoning in contexts of epistemic uncertainty. (shrink)

This work discusses an empirical study of reasoning as it occurs in conversations. Reasoning in this context has features not usually accounted for in standard methods for describing argumentation (e.g., Toulmin, (1964), Toulmin, Rieke, and Janik (1984)). For example, insufficient attention has been paid to challenges which can be used to shift the ground of an argument and to the development of multiple conversational grounds. Moreover, even though the value of cooperative efforts in building arguments is widely recognized, more needs (...) to be said about analyzing co-constructed arguments. This empirical work was primarily descriptive and concerned with how people construct arguments in conversations, but one goal of the study was to lay groundwork for comparing the quality of reasoning in conversations which differ with respect to whether the arguments they contain are primarily the contributions of individuals or are genuinely co-constructed arguments. (shrink)

This paper has three dimensions, historical, theoretical and social. The historical dimension is to show how the Ciceronian system of dialectical argumentation served as a precursor to computational models of argumentation schemes such as Araucaria and Carneades. The theoretical dimension is to show concretely how these argumentation schemes reveal the interdependency of rhetoric and logic, and so the interdependency of the normative with the empirical. It does this by identifying points of disagreement in a dialectical format through using argumentation schemes (...) and critical questions. The social dimension is to show how the Ciceronian dialectical viewpoint integrates with the use of computational tools that can be used to support the principle of reason-based deliberation and facilitate deliberative democracy. (shrink)

On the standard view, all presumptions share the same deontic function: they asymmetrically allocate the burden of proof. But what, exactly, does this function amount to? Once presumptions are rejected, do they place the burden of arguing, the burden of explanation, or the most general burden of reasoning on their opponents? In this paper, I take into account the differences between cognitive and practical presumptions and argue that the standard accounts of deontic function are at least ambiguous, and likely implausible. (...) As a result, they require qualifications. (shrink)

How do Dutch people let each other know that they disagree? What do they say when they want to resolve their difference of opinion by way of an argumentative discussion? In what way do they convey that they are convinced by each other’s argumentation? How do they criticize each other’s argumentative moves? Which words and expressions do they use in these endeavors? By answering these questions this short essay provides a brief inventory of the language of argumentation in Dutch.

The ArgumentThe purpose of this article is twofold. Firstly, I propose to analyze controversies using a “dialectical” model, in the sense described in Aristotle'sTopics. This approach presupposes that we temporarily disregard, for the sake of clarity, the concreteness of real life controversies in order to focus on their argumentative structure. From this point of view, the main advantage of controversies is that they allow the interlocutorsto testeach other's claims and therefore to arrive at relatively corroborated conclusions. This testing function in (...) a dialectical context is implemented through theassentto commonly accepted premises, and thenecessitywhich characterizes each step of the reasoning.Secondly, I shall apply this dialectical framework to the study of the controversy concerning the motion of the Earth, or rather a small episode of it. I shall examine an exchange of letters, written in 1616 and in 1624 respectively, between Galileo Galilei and Francesco Ingoli, one of his Aristotelian opponents. I shall then compare this exchange with the first day of Galileo'sDialogue Concerning the Two Chief Systems of the World, a fictional debate, where Galileo discusses some of the same arguments. While the first exemplifies what I call “negative” testing, and yields a refutation of the opponent's theses, the second exemplifies “positive” testing and yields a dialectical demonstration of the motion of the Earth. (shrink)

Parmenides as Secret Hero. Gregor Betz’s Theorie Dialektischer Strukturen (Theory of Dialectical Structures) Content Type Journal Article Pages 1-13 DOI 10.1007/s10503-011-9213-z Authors Frank Zenker, Department of Philosophy and Cognitive Science, Lund University, Kungshuset, Lundagård, 222 22 Lund, Sweden Journal Argumentation Online ISSN 1572-8374 Print ISSN 0920-427X.

Although debate is a richly structured and prevalent form of discourse, it has received little scholarly attention. Logicians have focused on the structure of individual arguments—how they divide into premises and conclusions, which in turn divide into various constituents. In contrast, I focus on the structure of sets of arguments, showing how arguments are themselves constituents in high-level dialectical structures. I represent debates and positions by graphs whose vertices correspond to arguments and whose edges correspond to two inter-argument relations: “dispute” (...) and “support,” respectively. On this basis I develop a theory of the structure of debate. (shrink)

This paper analyzes legal fact-argumentation in the framework of the argumentation-based litigation game by Xiong :16–19, 2012). Rather than as an ontological one, an ALG treats a legal fact as a fact-qua-claim whose acceptability depends on the reasons supporting it. In constructing their facts-qua-claims, parties to an ALG must interact to maintain a game-theoretic equilibrium. We compare the general interactional constraints that the civil and common law systems assign, and detail what the civil, administrative, and criminal codes of mainland China (...) require of the suitor, the respondent, and the trier to establish their respective S-, R- and T-facts. We also offer an improved version of the legal syllogism. (shrink)

Needed for such dialogue games as dialectic are appropriate standards of fairness and rationality. The rules of procedure of dialectic must describe a game playable by actual human participants. The present paper centers on certain idealizations of the dialectician that are not allowable.

Recent proposals for computer-assisted argumentation have drawn on dialectical models of argumentation. When used to assist public policy planning, such systems also raise questions of political legitimacy. Drawing on deliberative democratic theory, we elaborate normative criteria for deliberative legitimacy and illustrate their use for assessing two argumentation systems. Full assessment of such systems requires experiments in which system designers draw on expertise from the social sciences and enter into the policy deliberation itself at the level of participants.

Dispute types can roughly be divided in two classes. One class in whichthe notion of justification is fundamental, and one in which thenotion of opposition is fundamental. Further, for every singledispute type there exist various types of protocols to conduct such adispute. Some protocols permit local search (a process in which oneis allowed to justify claims partially, with the possibility to extendjustifications on request later), while other protocols rely on globalsearch (a process in which only entire arguments count as justifications).This (...) paper integrates the two above-mentioned types of dispute withthe use of a protocol that permits local search. The locality aspect isrelatively new to computer scientists, while the detailed computationalelaboration of the approach is relatively new to philosophical logicians.The proposed protocol is demonstrated with the help of eight benchmarks.These benchmarks are centered around the problem that co-concludingarguments sometimes accrue, and sometimes do not. (shrink)

In this paper a dialogue game for critical discussion is developed. The dialogue game is a formalisation of the ideal discussion model that is central to the pragma-dialectical theory of argumentation. The formalisation is intended as a preparatory step to facilitate the development of computational tools to support the pragma-dialectical study of argumentation. An important dimension of the pragma-dialectical discussion model is the role played by speech acts. The central issue addressed in this paper is how the speech act perspective (...) can be accommodated in the formalisation as a dialogue game. The starting point is an existing ‘basic’ dialogue game for critical discussion, in which speech acts are not addressed. The speech act perspective is introduced into the dialogue game by changing the rules that govern the moves that can be made and the commitments that these result in, while the rules for the beginning, for the end, and for the structure of the dialogue game remain unchanged. The revision of the move rules is based on the distribution of speech acts in the pragma-dialectical discussion model. The revision of the commitment rules is based on the felicity conditions that are associated with those speech acts. (shrink)

Some critical reactions hardly give clues to the arguer as to how to respond to them convincingly. Other critical reactions convey some or even all of the considerations that make the critic critical of the arguer’s position and direct the arguer to defuse or to at least contend with them. First, an explication of the notion of a critical reaction will be provided, zooming in on the degree of “directiveness” that a critical reaction displays. Second, it will be examined whether (...) there are normative requirements that enhance the directiveness of criticism. Does the opponent have in circumstances a dialectical obligation to provide clarifications, explanations, or even arguments? In this paper, it is hypothesized that the competitiveness inherent in critical discussion must be mitigated by making the opponent responsible for providing her counterconsiderations, if available, thus assisting the proponent in developing an argumentative strategy that defuses them. (shrink)

It furthers the dialectic when the opponent is clear about what motivates and underlies her critical stance, even if she does not adopt an opposite standpoint, but merely doubts the proponent’s opinion. Thus, there is some kind of burden of criticism. In some situations, there should an obligation for the opponent to offer explanatory counterconsiderations, if requested, whereas in others, there is no real dialectical obligation, but a mere responsibility for the opponent to cooperate by providing her motivations for being (...) critical. In this paper, it will be shown how a set of dialogue rules may encourage an opponent, in this latter type of situation, to provide her counterconsiderations, and to do so at an appropriate level of specificity. Special attention will be paid to the desired level of specificity. For example, the critic may challenge a thesis by saying “Why? Says who?,” without conveying whether she could be convinced by an argument from expert opinion, or from position to know, or from popular opinion. What are fair dialogue rules for dealing with less than fully specific criticism? (shrink)

This paper aims at a normative account of non-deductive argumentation schemes in the spirit of Hamblin’s dialectical philosophy. First, three principles are presented that characterize Hamblin’s dialectical stance. Second, argumentation schemes, which have hardly been examined in Hamblin’s book Fallacies, shall be dealt with by applying these principles, taking an argumentation scheme from authority as the leading example. Third, a formal dialectical system, along the lines indicated by Hamblin, shall be developed that includes norms for using argumentation schemes and norms (...) for responding to arguments that are presented as instantiating acceptable argumentation schemes. (shrink)

The use of ambiguous expressions in argumentative dialogues can lead to misunderstanding and equivocation. Such ambiguities are here called active ambiguities . However, even a normative model of persuasion dialogue ought not to ban active ambiguities altogether, one reason being that it is not always possible to determine beforehand which expressions will prove to be actively ambiguous. Thus, it is proposed that argumentative norms should enable each participant to put forward ambiguity criticisms as well as self-critical ambiguity corrections, inducing them (...) to improve their language if necessary. In order to discourage them from nitpicking and from arriving at excessively high levels of precision, the parties are also provided with devices with which to examine whether the ambiguity corrections or ambiguity criticisms have been appropriate. A formal dialectical system is proposed, in the Hamblin style, that satisfies these and some other philosophical desiderata. (shrink)

It is a feature of scientific inquiry that it proceeds alongside a multitude of non-scientific interests. This statement is as true of the scientific inquiries of previous centuries, many of which brought scientists into conflict with institutionalised religious thinking, as it is true of the scientific inquiries of today, which are conducted increasingly within commercial and political contexts. However, while the fact of the coexistence of scientific and non-scientific interests has changed little over time, what has changed with time is (...) the effect of this coexistence on scientific inquiry itself. While scientists may no longer construct their theories with various religious dictates in mind, growing commercial and political interests in science have served to distort the interpretation of science. Using the U.K.’s recent crisis with bovine spongiform encephalopathy (BSE) as my context, I examine two ways in which this distortion has occurred – the interpretation of the science of BSE by politicians and by commercial parties for the purposes of justifying policy decisions and informing the public of risk, respectively. Fallacious reasoning, I contend, is the manifestation of this distortion in these contexts. In demonstration of this claim, I examine how politicians and commercial parties alike have employed two fallacies in their assessments of the science of BSE. These fallacies extend in novel ways the set of so-called traditional informal fallacies. The interpretation of science, I conclude, is a rich context in which to conduct a study of fallacious reasoning; moreover, such a study can contribute in significant ways, I argue, to the public understanding of science. (shrink)

Allocating the burden of proof and intuitions in philosophical disputes.– This paper criticises the view that in philosophical disputes the onus probandi rests on those who advance a position that contradicts our basic intuitions. Such a rule for allocating the burden of proof may be an adequate reconstruction of everyday justification, but is unreasonable in the area of philosophy. In philosophy it is not only difficult to determine the plausibility of a proposition, at the same time contradictory claims may be (...) equally plausible. – In contrast to such common sense proposals I try to show that in philosophical disputes the burden of proof does not depend on the material content of speech acts. A speaker simply bears the burden of proof for a proposition p if he has asserted that p and has agreed to justify it. (shrink)

Presupposition has been described in the literature as closely related to the listener’s knowledge and the speaker’s beliefs regarding the other’s mind. However, how is it possible to know or believe our interlocutor’s knowledge? The purpose of this paper is to find an answer to this question by showing the relationship between reasoning, presumption and language. Presupposition is analyzed as twofold reasoning process: on the one hand, the speaker by presupposing a proposition presumes that his interlocutor knows it; on the (...) other hand, the listener reconstructs the propositions taken for granted and assesses them against the shared presumptions. The possibility of reconstructing a presupposition is distinguished from its assessment, where the consistency of the presupposition with the shared or common ground is evaluated, and its reasonableness established. The analysis of presuppositions from an argumentative perspective provides an instrument for evaluating the reasonableness of a presupposition and understanding its dialogical effect. On this view, the dialogical force of a presupposition lies in its presumptive nature, which sets and shifts the burden of proving its unacceptability or unreasonableness. (shrink)

According to the so-called presumption of equality, a person who does not know whether there is an acceptable reason for differential treatment should just presume the similarity of the cases and treat them equally. If we assume that the presumption of equality is an acceptable moral principle, at least when the allocation cannot be postponed and an equal distribution of goods is possible, then an important question arises: when exactly does the allocator have sufficient reasons for differential treatment and is (...) not relevantly ignorant? This is a question about the required strength of the “acceptable reasons” for differential treatment. It has been commonplace to think that the presumption of equality demands that the reasons that refute the presumption must be very strong and that differential treatment requires that there is a proper justification for the claim that the cases are relevantly different. I will argue, however, that refuting the presumption and solving the issue are two separate matters. A person can have good enough reasons for rejecting the presumption that the cases are relevantly similar without having reasons that she could present as a full justification for the claim that the cases are relevantly different. A precondition of the applicability of the presumption of equality is ignorance, but not ignorance in the sense of “not having a full justification”. (shrink)

The present study explored several dispositional factors associated with individual differences in lay adult’s interpretation of when an arguer is, or is not, committed to a statement. College students were presented with several two-person arguments in which the proponent of a thesis conceded a key point in the last turn. Participants were then asked to indicate the extent to which that concession implied a change in the proponent’s attitude toward any of the previous statements in the argument. Participants designated as (...) ‘liberal’ used the concession to infer substantial change in commitment to earlier statements in the argument. A group designated as ‘conservative’ were reluctant to make any such inferences. A discriminant analysis indicated that variables assessing participants’ attitudes toward argument as well as their cognitive and communication styles jointly predicted their liberal or conservative status. The discriminant function and follow-up group comparisons indicated that liberals were more likely than conservatives to engage in argument. This included a greater tendency to use argument as a source of knowledge. Liberals also employed a more sophisticated message design logic than conservatives on a communication task. The groups did not clearly differ with respect to participants’ implicit theory of argument, though trends were present that merit attention in future research. Implications of these findings for future research on lay interpretations of commitment are discussed. (shrink)

La concepción predominante de la argumentación sigue privilegiando la dimensión representacional del lenguaje y, en consecuencia, ignora o infravalora las funciones compromisorias, directivas o expresivas de la argumentación. En este artículo examino los usos de la argumentación en la esfera pública -con especial atención a la deliberación y a la negociación- para poner de manifiesto y reivindicar la importancia de las funciones no persuasivas de la argumentación, entre las que se destaca la construcción y moldeado de identidades sociales.

This paper revisits the challenge of Berman and Hafner’s “missing link” paper on representing teleological structure in case-based legal reasoning. It is noted that this was mainly an ontological challenge to represent some of what made legal reasoning distinctive, which was given less attention than factual similarity in the dominant AI and Law paradigm, deriving from HYPO. The response to their paper is noted and briefly evaluated. A parallel is drawn to a new challenge to provide deep structure to the (...) legal context of textual meaning, drawing on the forthcoming work of two Constitutional law scholars who appear to place some faith in the ways of thinking that AI and Law has developed. (shrink)

There is the idea that rational belief for a single individual can be constructed via a process of unilateral argument. To preempt antipathy between the AI communities that can claim the idea that rational belief can be so constructed, we trace the idea to the beginning of this century, to Keynes' dispute with Russell over logic and probability. We review how Keynesian ideas were revived in AI's work on non-monotonic reasoning and parallel developments in philosophical logic.

In this paper, we closely examine the various ways in which a multi-party argumentative discussion—argumentative polylogue—can be analyzed in a dialectical framework. Our chief concern is that while multi-party and multi-position discussions are characteristic of a large class of argumentative activities, dialectical approaches would analyze and evaluate them in terms of dyadic exchanges between two parties: pro and con. Using as an example an academic committee arguing about the researcher of the year as well as other cases from argumentation literature, (...) we scrutinize the advantages and pitfalls of applying a dialectical framework to polylogue analysis and evaluation. We recognize two basic dialectical methods: interpreting polylogues as exchanges between two main camps and splitting polylogues into a multitude of dual encounters. On the basis of this critical inquiry, we lay out an argument expressing the need for an improved polylogical model and propose its basic elements. (shrink)

Some critical reactions hardly give clues to the arguer as to how to respond to them convincingly. Other critical reactions convey some or even all of the considerations that make the critic critical of the arguer’s position and direct the arguer to defuse or to at least contend with them. First, an explication of the notion of a critical reaction will be provided, zooming in on the degree of “directiveness” that a critical reaction displays. Second, it will be examined whether (...) there are normative requirements that enhance the directiveness of criticism. Does the opponent have in circumstances a dialectical obligation to provide clarifications, explanations, or even arguments? In this paper, it is hypothesized that the competitiveness inherent in critical discussion must be mitigated by making the opponent responsible for providing her counterconsiderations, if available, thus assisting the proponent in developing an argumentative strategy that defuses them. (shrink)

Arguments from analogy are pervasive in everyday reasoning, mathematics, philosophy, and science. Informal logic studies everyday argumentation in ordinary language. A branch of fuzzy logic, approximate reasoning, seeks to model facets of everyday reasoning with vague concepts in ill-defined situations. Ways of combining the results from these fields will be suggested by introducing a new argumentation scheme—a fuzzy analogical argument from classification—with the associated critical questions. This will be motivated by a case study of analogical reasoning in the virtual friendship (...) debate within information ethics. The virtual friendship debate is a disagreement over whether virtual friendships are genuine friendships. It will be argued that the debate could move away from its current impasse, caused by unproductive metaphysical and logical assumptions, if extant arguments are reinterpreted as fuzzy analogical arguments from classification, and subjected to a new set of critical questions which would replace the quest for facts of essence about friendship with an emphasis on empirical data, persuasion, and definitional power. (shrink)

The question of who has the burden of proof is often important in practice. We must frequently make decisions and act on the basis not of conclusive evidence but of what is reasonable to presume true. Consequently, it happens that a given practical question must be solved by referring to principles that explicitly or implicitly determine, at least partly, where the burden of proof should rest. In this essay, I consider the role of the logic of the burden of proof (...) in a debate on global justice. In particular, I ask how the logic of the burden of proof is seen by those who defend conservative positions in a debate and deny our obligations to reduce poverty beyond borders. I argue that defenders of conservative positions tend to shift the burden of proof in an unjustified way. (shrink)