The primary aim of this chapter is to explain the nature of evidential reasoning, the characteristic difficulties encountered, and the tools to address these difficulties. Our focus is on evidential reasoning in criminal cases. There is an extensive scholarly literature on these topics, and it is a secondary aim of the chapter to provide readers the means to find their way in historical and ongoing debates.

Use of argumentation methods applied to legal reasoning is a relatively new field of study. The book provides a survey of the leading problems, and outlines how future research using argumentation-based methods show great promise of leading to useful solutions. The problems studied include not only these of argument evaluation and argument invention, but also analysis of specific kinds of evidence commonly used in law, like witness testimony, circumstantial evidence, forensic evidence and character evidence. New tools for analyzing these kinds (...) of evidence are introduced. (shrink)

In The Uses of Argument, Stephen Toulmin proposed a model for the layout of arguments: claim, data, warrant, qualifier, rebuttal, backing. Since then, Toulmin’s model has been appropriated, adapted and extended by researchers in speech communications, philosophy and artificial intelligence. This book assembles the best contemporary reflection in these fields, extending or challenging Toulmin’s ideas in ways that make fresh contributions to the theory of analysing and evaluating arguments.

J. Anthony Blair is a prominent international figure in argumentation studies. He is among the originators of informal logic, an author of textbooks on the informal logic approach to argument analysis and evaluation and on critical thinking, and a founder and editor of the journal Informal Logic. Blair is widely recognized among the leaders in the field for contributing formative ideas to the argumentation literature of the last few decades. This selection of key works provides insights into the history of (...) the field of argumentation theory and various related disciplines. It illuminates the central debates and presents core ideas in four main areas: Critical Thinking, Informal Logic, Argument Theory and Logic, Dialectic and Rhetoric. (shrink)

According to the argument scheme approach, to evaluate a given scheme-saturating instance completely does entail asking all critical questions relevant to it. Although this is a central task for argumentation theorists, the field currently lacks a method for providing a complete argument evaluation. Approaching this task at the meta-level, we combine a logical with a substantive approach to the argument schemes by starting from Toulmin’s schema: ‘data, warrant, so claim’. For the yet more general schema: ‘premise; if premise, then conclusion; (...) so conclusion’, we forward a meta-level CQ-list that is arguably both complete and applicable. This list should inform ongoing theoretical efforts at generating appropriate object-level CQs for specific argument schemes. (shrink)

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)

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)

Argument invention is a method that can be used to help an arguer find arguments that could be used to prove a claim he needs to defend. The aim of this paper is to show how argumentation systems recently developed in artificial intelligence can be applied to the task of argument invention. One such system called Carneades is featured. Carneades can be used to analyze arguments, evaluate arguments, to make an argument diagram, and to construct arguments from a database. Using (...) some simple examples, the paper explains how Carneades works as a system of argument invention. (shrink)

Amphiboly has been widely recognized, starting from the time of Aristotle, as an informal fallacy arising from grammatical ambiguity. This paper applies the profiles of dialogue tool to the fallacy of amphiboly, providing a five-step evidence-based procedure whereby a syntactically ambiguous sentence uttered in a natural language text can be evaluated as committing a fallacy of amphiboly. A user applies the tool to a natural language text by comparing a descriptive graph, representing how the argumentation actually went, to a normative (...) graph, representing how the argumentation should ideally have proceeded. (shrink)

This paper addresses the problem posed by the current split between the two opposed hypotheses in the growing literature on the fallacy of begging the question the epistemic hypothesis, based on knowledge and belief, and the dialectical one, based on formal dialogue systems. In the first section, the nature of split is explained, and it is shown how each hypothesis has developed. To get the beginning reader up to speed in the literature, a number of key problematic examples are analyzed (...) illustrating how both approaches can be applied. Useful tools are brought to bear on them, including the automated argument diagramming system Araucaria, and profiles of dialogue used to represent circular argumentation in a dialogue tableau format. These tools are used to both to model circular reasoning and to provide the contextual evidence needed to properly determine whether the circular reasoning in a given case is better judged fallacious or not. A number of technical problems that have impeded the development of both hypotheses are studied. One central problem is the distinction between argument and explanation. It is concluded that the best way to move forward and solve these problems is to reformulate the two hypotheses in such a way that they might be able to co-exist. On this basis, a unified methodology is proposed that allows each hypothesis to move forward as a legitimate avenue for research using the same tools. (shrink)

How to model relevance in argumentation is an important problem for informal logic. Dialectical relcvance is determined by the use of an argument for some purpose in different types of dialogue, according to the ncw dialectic. A central type of dialogue is persuasion dialogue in which one participant uses rational argumentation to try to get the other participant to accept a designated proposition. In this paper, a method for judging relevance in persuasion dialogue is presented. The method is based on (...) using the technique of argument diagramming. (shrink)

SummaryThis paper studies some classic cases of the fallacy of begging the question based on appeals to testimony containing circular reasoning. For example, suppose agents a, b and c vouch for d’s credentials, and agents b, d, and e vouch for a’s credentials. Such a sequence of reasoning is circular because a is offering testimony for d but d is offering testimony for a. The paper formulates and evaluates restrictions on the use of testimonial evidence that might be used to (...) deal with such problematic arguments. One is called the Non-repeater Rule: in an extended sequence of argumentation based on testimony, once a source x has been appealed to at any given point in the sequence, that same source x must never be appealed to again at any next point in the same sequence. (shrink)

. A heuristic search procedure for inventing legal arguments is built on two tools already widely in use in argumentation. Argumentation schemes are forms of argument representing premise‐conclusion and inference structures of common types of arguments. Schemes especially useful in law represent defeasible arguments, like argument from expert opinion. Argument diagramming is a visualization tool used to display a chain of connected arguments linked together. One such tool, Araucaria, available free at , helps a user display an argument on the (...) computer screen as an inverted tree structure with an ultimate conclusion as the root of the tree. These argumentation tools are applicable to analyzing a mass of evidence in a case at trial, in a manner already known in law using heuristic methods and Wigmore diagrams . In this paper it is shown how they can be automated and applied to the task of inventing legal arguments. One important application is to proof construction in trial preparation. (shrink)

In this paper, a case study is conducted to test the capability of the Carneades Argumentation System to model the argumentation in a case where forensic evidence was collected in an investigation triggered by a conflict among art experts on the attribution of a painting to Leonardo da Vinci. A claim that a portrait of a young woman in a Renaissance dress could be attributed to da Vinci was initially dismissed by art experts. Forensic investigations were carried out, and evidence (...) was collected by art history experts and scientific experts. The expert opinions were initially in conflict, but new evidence shifted the burden of proof onto the side of the skeptics. This paper presents an analysis of the structure of the interlocking argumentation in the case using argument mapping tools to track the accumulation of evidence pro and con. (shrink)

The present article deals with reported speech as an element of argumentation in the newspaper discourse of Great Britain viewed in the unity of its syntactic and semantic characteristics and argumentative functions. Theoretically, the research is based on the dialogic understanding of quotations, the dialogue theory by Bakhtin and contemporary argumentation theory. The proposed integral approach to reported speech combining linguistics with logic and argumentation theory revealed the relations between purely linguistic characteristics of reported speech with its functioning in argumentative (...) discourse of contemporary British press. (shrink)

Deductivism is not merely a logical technique, but also a theory of normativity: it provides an objective and universal standard of evaluation. Contemporary dialectical logic rejects deductive normativity, replacing its universal standard by an intersubjective standard. It is argued in this paper that dialectical normativity does not improve upon deductive normativity. A dialogico-rhetorical alternative is proposed.

This study used Toulmin's analytical framework of argumentative structure in order to examine employees' argumentative discourse on the way they handle conflict situations in their workplace. The way in which this analytical tool has been applied here challenges critics on the usefulness of the particular analytical tool for the analysis of real-life argumentation. The definition of argumentative elements according to their function in the context of a particular argument, together with the analysis beyond the level of what has been stated (...) explicitly enabled a comprehensive understanding of how specific information, statements or assumptions are interpreted and utilized in arguments examined. Finally, the acknowledgment of the importance of `field-dependency' of argumentative discourse, through the consideration of the social context within which this discourse is embedded, elicited the way in which this context made employees' argumentation a meaningful and acceptable discourse in this particular setting. (shrink)

The aim of this paper is to propose foundations for a formal model of representation and numerical evaluation of a possibly broad class of arguments, including those that occur in natural discourse. Since one of the most characteristic features of everyday argumentation is the occurrence of convergent reasoning, special attention should be paid to the operation ⊕, which allows us to calculate the logical force of convergent arguments with an accuracy not offered by other approaches.

Naszym celem jest dostarczenie formalnego modelu oceny możliwie szerokiej klasy argumentacji, w szczególności tych, które pojawiają się w kontekstach naturalnych. We wprowadzeniu przedstawiamy elementarne sposoby rozbudowywania argumentacji prostych w coraz bardziej złożone struktury. W drugim rozdziale podajemy ścisłe definicje pojęć służących do opisu tych struktur — argumentację definiujemy jako niepusty i skończony zbiór sekwentów, tj. jako niepustą i skończoną relację zachodzącą pomiędzy niepustymi i skończonymi zbio-rami zdań a pojedynczymi zdaniami danego języka; wprowadzamy także kilka pojęć (nie-spójność, rozbieżność, kolistość), które pozwalają (...) wyróżniać niektóre nietypowe lub wadliwe struktury argumentacyjne. W trzecim rozdziale proponujemy ogólną, liczbową metodę oceny siły argumentacji. Metoda ta pokazuje, jak wiarygodność przesłanek pierwszych przekłada się na wiarygodność konkluzji głównej w zależności od budowy argumentacji (wiarygodność wyrażamy za pomocą liczb wymiernych z domkniętego przedziału <0, 1>). Jedną z charakterystycznych własności argumentacji potocznej jest występowanie w niej wzajemnie wzmacniających się tzw. rozumowań równoległych. Dlatego za istotny składnik proponowanej metody należy uznać wzór: a * b = 2a+2b-2ab-1. Wzór ten pozwala obliczyć wiarygodność (konkluzji) dowolnej argumentacji równoległej, składającej się z dwóch wzajemnie niezależnych rozumowań, które brane z osobna uwiarygodniają konkluzję w stopniach a oraz b (zakładamy przy tym, że obie te wartości są większe niż ½). (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)

The paper considers the role of modality in the rational reconstruction of standpoints and arguments. The paper examines in what conditions modal markers can act as argumentative indicators and what kind of cues they provide for the reconstruction of argument. The paper critically re-examines Toulmin’s hypothesis that the meaning of the modals can be analyzed in terms of a field-invariant argumentative force and field-dependent criteria in the light of the Theory of Relative Modality developed within linguistic semantics, showing how this (...) theory can provide a more adequate model for exploiting the modals as indicators. The resulting picture confirms Toulmin’s intuition only in part: on the one hand the modals are always relational in nature and dependent on a contextual conversational background of propositions; on the other hand only epistemic-doxastic modals directly express a speech-act level inferential relation between a set of premises and a standpoint. Other modalities express relations (e.g. causal or final relations) better seen as part of the content of the argument whose argumentative relevance depends on the argumentation scheme employed. Thus non-epistemic modals function as argumentative indicators only indirectly. (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 Argument Web is maturing as both a platform built upon a synthesis of many contemporary theories of argumentation in philosophy and also as an ecosystem in which various applications and application components are contributed by different research groups around the world. It already hosts the largest publicly accessible corpora of argumentation and has the largest number of interoperable and cross compatible tools for the analysis, navigation and evaluation of arguments across a broad range of domains, languages and activity types. (...) Such interoperability is key in allowing innovative combinations of tool and data reuse that can further catalyse the development of the field of computational argumentation. The aim of this paper is to summarise the key foundations, the recent advances and the goals of the Argument Web, with a particular focus on demonstrating the relevance to, and roots in, philosophical argumentation theory. (shrink)

Selinger provides a new take on what is being referred to in the computational literature as ‘structured argumentation’. In this commentary the differences and similarities with existing work are highlighted as a way of demonstrating how philosophical and computational approaches to argumentation are increasingly coming together and complementing one another.

The concept of argumentation in AI is based almost exclusively on the use of formal, abstract representations. Despite their appealing computational properties, these abstractions become increasingly divorced from their real world counterparts, and, crucially, lose the ability to express the rich gamut of natural argument forms required for creating effective text. In this paper, the demands that socially situated argumentation places on knowledge representation are explored, and the various problems with existing formalisations are discussed. Insights from argumentation theory and social (...) psychology are then adduced as key contributions to a notion of social context which is both computationally tractable and suitably expressive for handling the complexities of argumentation found in natural language. (shrink)

In today’s ‘networked’ public sphere, arguers are faced with countless controversies roaming out there. Knowing what is at stake at any point in time, and keeping under control the contribution one’s arguments make to the different interrelated issues requires careful craft Keeping in touch with Pragma-Dialectics. In honor of Frans H. van Eemeren. John Benjamins, Amsterdam, 2011). In this paper, I explore the difficulty of determining what is at stake at any moment of the argumentative situation and explore the challenge (...) that that creates for examining the strategic shape of arguments. I argue that a meaningful examination of networked argumentative encounters requires that the boundaries of an encounter remain ‘fluid. In dealing with the fluid boundaries, I suggest to identify “argumentative associates” and “standing standpoints”. (shrink)

I take 'informal logic' to be the (descriptive and normative) study of 'real arguments'-arguments which are or have been used with the aim of convincing others of a point of view. I argue that the informal logic tradition thus conceived (i) lends strong support to something like Quine's view that our beliefs really support one another like the filaments in a spider's web--and thus that the traditional view that implication is an asymmetric relation is false; (ii) suggests that the classic (...) division of arguments into deductive and inductive has distorted our thinking about the evaluation of real arguments; and (iii) implies that naturalised epistemology is on the right track. (shrink)

Logicians disagree on (1) criteria for the presence of an argument, (2) criteria for adding implicit premises and (3) criteria for linking premises. I attempt to resolve all three problems, and in the process to remove the main obstacles to teaching diagramming. The first problem is resolved by working with real discourse that students find on their own, rather than the artificial examples and problems found in logic texts; it is further reduced by examining the different uses of argument and (...) understanding the extent to which the basic rules of diagramming are the same for the various uses. The other disagreements persist because logicians neglect to clarify the principal type of eakness we remedy by adding implicit premises and linking premises: in real discourse we do so to block substantive counterexamples, an idea correlated with that of substantive deduction, discussed by Govier, Wright and others. (shrink)

This paper attempts to systematically characterize critical reactions in argumentative discourse, such as objections, critical questions, rebuttals, refutations, counterarguments, and fallacy charges, in order to contribute to the dialogical approach to argumentation. We shall make use of four parameters to characterize distinct types of critical reaction. First, a critical reaction has a focus, for example on the standpoint, or on another part of an argument. Second, critical reactions appeal to some kind of norm, argumentative or other. Third, they each have (...) a particular illocutionary force, which may include that of giving strategic advice to the other. Fourth, a critical reaction occurs at a particular level of dialogue (the ground level or some meta-level). The concepts here developed shall be applied to discussions of critical reactions by Aristotle and by some contemporary authors. (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).

We develop conceptions of arguments and of argument types that will, by serving as the basis for developing a natural classification of arguments, benefit work in artificial intelligence. Focusing only on arguments construed as the semantic entities that are the outcome of processes of reasoning, we outline and clarify our view that an argument is a proposition that represents a fact as both conveying some other fact and as doing so wholly. Further, we outline our view that, with respect to (...) arguments that are propositions, (roughly) two arguments are of the same type if and only if they represent the same relation of conveyance and do so in the same way. We then argue for our conceptions of arguments and argument types, and compare them to alternative positions. We also illustrate the need for, and some of the strengths of, our approach to classifying arguments through an examination of aspects of two prominent and recent attempts to classify arguments using argumentation schemes, namely those of M. Kienpointner and D. Walton. Finally, we clarify how our conception of arguments and of argument types can assist in developing an exhaustive classification of arguments. (shrink)

Mediation is an alternative dispute resolution process that is becoming more and more popular particularly in English-speaking countries. In contrast to traditional litigation it has not benefited from technological advances and little research has been carried out to make this increasingly widespread practice more efficient. The study of argumentation in dispute mediation hitherto has largely been concerned with theoretical insights. The development of argumentation theories linked to computational applications opens promising new horizons since computational tools could support mediators, making sessions (...) quicker and more efficient. For this, we need tools for close analysis of mediation discourse in order to explore the argumentative activity in depth, and ultimately get an accurate image of how dialogues unfold in this particular context. This paper therefore aims at laying the foundations of a theory of close analysis for discourse in dispute mediation. Theories provided by the literature serve as a basis for argumentative analyses of transcripts of mediation sessions in order to deliver a clear image of the argumentative structure. Analyses of the argumentative strategies in mediation discourse will allow for the development of a dialogue protocol that can be used to develop operational models which can be embodied in software to help make the mediation process easier and more effective. (shrink)

Used informally, the Reductio ad Absurdum (RAA) consists in reasoning appealing to the logically implied, absurd consequences of a hypothetical proposition, in order to refute it. This kind of reasoning resembles the Argument from Consequences, which appeals to causally induced consequences. These types of argument are sometimes confused, since it is not worked out how these different kinds of consequences should be distinguished. In this article it is argued that the logical consequences in RAA-argumentation can take different appearances and that (...) it therefore must be concluded that RAA cannot be characterised by a specific content, but must instead be characterised as an argument form. Furthermore, clues are provided to distinguish RAA reasoning from the Argument from Consequences. (shrink)

The paper outlines a conceptual framework for the critical assessment of argumentation which differs in some of its core characteristics from conventional approaches: it is resolutely semantic rather than formal in its method; it centers on obligations rather than beliefs; and its analytical focus is on the contingent necessity of conclusions, rather than on their persuasiveness or formal validity. The paper briefly illustrates the applications of this conceptual framework by reanalyzing a couple of examples taken from the argumentation analysis literature.

In this paper, a survey is presented of the main approaches to the structure of argumentation. The paper starts with a historical overview of the distinctions between various types of argument structure. Next, the main definitions given in the various approaches are discussed as well as the methods that are proposed to deal with doubtful cases.

In this paper, it is explained that a dialogical approach to complex argumentation can be fruitful for solving two important problems concerning the analysis of the argumentation structure. First, such an approach makes it possible to clarify the distinction between coordinative and multiple argumentation structures, and to identify clues in the presentation for each of these structures. Second, a dialogical approach can provide a basis for dealing more adequately with refutations of counterarguments.

Some conspicuous characteristics of argumentation as we all know this phenomenon from our shared everyday experiences are in my view vital to its theoretical treatment because they should have methodological consequences for the way in which argumentation research is conducted. To start with, argumentation is in the first place a communicative act complex, which is realized by making functional verbal communicative moves.

Carneades is an open source argument mapping application and a programming library for building argumentation support tools. In this paper, Carneades’ support for argument reconstruction, evaluation and visualization is illustrated by modeling most of the factual and legal arguments in Popov v Hayashi.

A generation before Beardsley, legal scholar John Henry Wigmore invented a scheme for representing arguments in a tree diagram, aimed to help advocates analyze the proof of facts at trial. In this essay, I describe Wigmore's "Chart Method" and trace its origin and influence. Wigmore, I argue, contributes to contemporary theory in two ways. His rhetorical approach to diagramming provides a novel perspective on problems about the theory of reasoning, premise adequacy, and dialectical obligations. Further, he advances a novel solution (...) to the problem of assessing argument quality by representing the strength of argument in meeting objections. (shrink)

Given the pragmatic tum recently taken by argumentation studies, we owe renewed attention to Henry Johnstone's views on the primacy of process over product. In particular, Johnstone's decidedly non-cooperative model is a refreshing alternative to the current dialogic theories of arguing, one which opens the way for specifically rhetorical lines of inquiry.

Douglas Walton has been right in calling us to attend to the pragmatics of argument. He has, however, also insisted that arguments should be understood and assessed by considering the functions they perform; and from this, I dissent. Argument has no determinable function in the sense Walton needs, and even if it did, that function would not ground norms for argumentative practice. As an alternative to a functional theory of argumentative pragmatics, I propose a design view, which draws attention to (...) the way participants strategically undertake and impose norms on themselves in order for their arguments to have force. (shrink)

Corroborative evidence has a dual function in argument. Primarily, it functions to provide direct evidence supporting the main conclusion. But it also has a secondary, bolstering function which increases the probative value of some other piece of evidence in the argument. This paper argues that the bolstering effect of corroborative evidence is legitimate, and can be explained as counter–rebuttal achieved through inference to the best explanation. A model (argument diagram) of corroborative evidence, representing its structure and operation as a schematic (...) pattern of defeasible argument is also supplied. In addition to explaining the operation and theoretical foundation of corroborative evidence, the model facilitates the correct analysis and guides the evaluation (assessment and critique) of corroborative evidence as it occurs in argument. (shrink)