Knowledge in a Social World offers a philosophy for the information age. Alvin Goldman explores new frontiers by creating a thoroughgoing social epistemology, moving beyond the traditional focus on solitary knowers. Against the tides of postmodernism and social constructionism Goldman defends the integrity of truth and shows how to promote it by well-designed forms of social interaction. From science to education, from law to democracy, he shows why and how public institutions should seek knowledge-enhancing practices. The result is a bold, (...) timely, and systematic treatment of the philosophical foundations of an information society. (shrink)

This book identifies 25 argumentation schemes for presumptive reasoning and matches a set of critical questions to each.

Fundamentals of Critical Argumentation presents the basic tools for the identification, analysis, and evaluation of common arguments for beginners. The book teaches by using examples of arguments in dialogues, both in the text itself and in the exercises. Examples of controversial legal, political, and ethical arguments are analyzed. Illustrating the most common kinds of arguments, the book also explains how to evaluate each kind by critical questioning. Douglas Walton shows how arguments can be reasonable under the right dialogue conditions by (...) using critical questions to evaluate them. The book teaches by example, both in the text itself and in exercises, but it is based on methods that have been developed through the author's thirty years of research in argumentation studies. (shrink)

What system of morals should rational people select as the best for society? Using a contemporary psychological theory of action and of motivation, Richard Brandt's Oxford lectures argue that the purpose of living should be to strive for the greatest good for the largest number of people. Brandt's discussions range from the concept of welfare to conflict between utilitarian moral codes and the dictates of self-interest.

The aim of the paper is to advance the theory of argument or inference schemes by suggesting answers to questions raised by Walton's Argumentation Schemes for Presumptive Reasoning (1996), specifically on: the relation between argument and reasoning; distinguishing deductive from presumptive schemes, the origin of schemes and the probative force of their use; and the motivation and justification for their associated critical questions.

In this paper we defend a particular version of the epistemic approach to argumentation. We advance some general considerations in favor of the approach and then examine the ways in which different versions of it play out with respect to the theory of fallacies, which we see as central to an understanding of argumentation. Epistemic theories divide into objective and subjective versions. We argue in favor of the objective version, showing that it provides a better account than its subjectivist rival (...) of the central fallacy of begging the question. We suggest that the strengths of the objective epistemic theory of fallacies provide support for the epistemic approach to argumentation more generally. (shrink)

Critical Thinking as Applied Epistemology: Relocating Critical Thinking in the Philosophical Landscape.

One of the crucial problems of argumentation schemes as illustrated in (Walton, Reed & Macagno 2008) is their practical use for the purpose of analyzing texts and producing arguments. The high number and the lack of a classification criterion make this instrument extremely difficult to apply practically. The purpose of this paper is to analyze the structure of argumentation schemes and outline a possible criterion of classification based on alternative and mutually-exclusive possibilities. Such a criterion is based not on what (...) an argument is, but how it can be understood and interpreted. The schemes are grouped according to an end-means principle, which is strictly bound to the ontological structure of the conclusion and the premises. On this view, a scheme can be selected according to the intended or reconstructed purpose of an argument and the possible strategies that can be used to achieve it. (shrink)

Das spezifische Ziel von Argumentationen ist nicht einfach, den Adressaten etwas glauben zu machen - dies wäre bloße Rhetorik ﷓, sondern: den Adressaten beim Erkennen der Akzeptabilität (insbesondere der Wahrheit) der These anzuleiten und ihn so zu begründetem Glauben, zu Erkenntnis zu führen. Argumentationen leiten das Erkennen an, indem sie in ihren Argumenten hinreichende Akzeptabilitätsbedingungen der These als erfüllt beurteilen und so den Adressaten implizit auffordern, diese Bedingungen zu überprüfen. Argumentationen sind gültig, wenn sie prinzipiell das Erkennen anleiten können; d. (...) h. wenn die genannten Akzeptabilitätsbedingungen hinreichend sind, wenn sie tatsächlich erfüllt (die Argumente also wahr) sind und wenn es irgendjemanden gibt, der zwar die Akzeptabilität der Argumente, nicht aber die der These erkannt hat. Eine gültige Argumentation ist adäquat, um einen bestimmten Adressaten rational zu überzeugen, wenn dieser u. a. die Akzeptabilität der Argumente, nicht aber die der These erkannt hat. Die in gültigen Argumentationen als erfüllt beurteilten Akzeptabilitätsbedingungen sind Konkretisierungen allgemeiner Erkenntnisprinzipien für die spezifische These, z. B. des deduktiven Erkenntnisprinzips: 'Eine Proposition ist wahr, wenn sie von wahren Propositionen logisch impliziert wird.' oder des erkenntnisgenetischen Erkenntnisprinzips: 'Eine Proposition ist wahr, wenn sie korrekt verifiziert worden ist.' Eine Konkretisierung des deduktiven Prinzips für eine These p wäre z. B.: 'p ist wahr, 1. wenn q und r wahr sind und 2. wenn q und r zusammen p logisch implizieren.' Sind beide Bedingungen erfüllt, so könnte 'q; r; also p.' eine gültige deduktive Argumentation sein. Die verschiedenen Argumentationstypen unterscheiden sich danach, auf welchem Erkenntnisprinzip sie basieren. Das argumentativ angeleitete Erkennen der Akzeptabilität der These funktioniert so: Der Adressat benutzt das von ihm (zumindest implizit) gewußte allgemeine Erkenntnisprinzip als Checkliste, auf der er nach dem Vorbringen der Argumente abhakt, welche Akzeptabilitätsbedingung des Erkenntnisprinzips durch das Zutreffen des Arguments jeweils erfüllt wird. Auf der Basis dieser Funktionsbestimmung werden in der "Praktischen Argumentationstheorie" (erstmalig) präzise Gültigkeitskriterien für Argumentationen allgemein und für mehrere spezielle Argumentationstypen entwickelt, erkenntnistheoretisch begründet und auf komplexe Argumentationsbeispiele aus Philosophie, Wissenschaft, Technik und Kultur angewendet. Die Analyse der erkenntnistheoretischen Grundlagen - der zugrundeliegenden Erkenntnisprinzipien - vor allem der interpretierenden und praktischen Argumentationen ist zudem von erheblicher Bedeutung weit über die Argumentationstheorie hinaus: für die Interpretationstheorie, die Handlungstheorie und die praktische Philosophie. (shrink)

We are pleased to publish this WSIA edition of Trudy’s Govier’s seminal volume, Problems in Argument Analysis and Evaluation. Originally published in 1987 by Foris Publications, this was a pioneering work that played a major role in establishing argumentation theory as a discipline. Today, it is as relevant to the field as when it first appeared, with discussions of questions and issues that remain central to the study of argument. It has defined the main approaches to many of those issues (...) and guided the ways in which we might respond to them. From this foundation, it sets the stage for further investigations and emerging research. This is a second edition of the book that is corrected and updated by the author, with new prefaces to each chapter. (shrink)

This is an introductory guidebook to the basic principles of how to construct good arguments and how to criticeze bad ones. It is non-technical in its approach and is based on 150 key examples, each discussed and evaluated in clear, illustrative detail. Professor Walton, a leading authority in the field of informal logic, explains how errors, fallacies, and other key failures of argument occur. He shows how correct uses of argument are based on sound strategies for reasoned persuasion and critical (...) responses. Among the many subjects covered are: forms of valid argument, relevance, appeals to emotion, personal attack, uses and abuses of expert opinion, problems in deploying statistics, loading terms, equivocation, arguments from analogy, and techniques of posing, replying to, and criticizing questions. The book will be ideally suited to courses in informal logic and in the introduction to philosophy. It will also prove valuable to studetns of pragmatics, rhetoric, and speech communication. (shrink)

Argumentation schemes are forms of reasoning that are fallible but correctable within a self-correcting framework. Their use provides a basis for taking rational action or for reasonably accepting a conclusion as a tentative hypothesis, but they are not deductively valid. We argue that teleological reasoning can provide the basis for justifying the use of argument schemes both in monological and dialogical reasoning. We consider how such a teleological justification, besides being inspired by the aim of directing a bounded cognizer to (...) true belief and correct choices, needs to take into account the attitudes of dialogue partners as well as normative models of dialogue and communicative activity types, in particular social and cultural settings. (shrink)

Argumentation schemes are forms of argument that capture stereotypical patterns of human reasoning, especially defeasible ones like argument from expert opinion, that have proved troublesome to view deductively or inductively. Much practical work has already been done on argumentation schemes, proving their worth in A1 [19], but more precise investigations are needed to formalize their structures. The problem posed in this paper is what form justification of a given scheme, as having a certain precise structure of inference, should take. It (...) is argued that defeasible argumentation schemes require both a systematic and a pragmatic justification, of a kind that can only be provided by the case study method of collecting key examples of arguments of the types traditionally classified as fallacies, and subjecting them to comparative examination and analysis. By this method, postulated structures for schemes can be formulated as hypotheses to solve three kinds of problems: (1) how to classify such arguments into different types, (2) how to identify their premises and conclusions, and (3) how to formulate the critical questions used to evaluate each type of argument. (shrink)

This paper presents a formalization of informal logic using the Carneades Argumentation System, a formal, computational model of argument that consists of a formal model of argument graphs and audiences. Conflicts between pro and con arguments are resolved using proof standards, such as preponderance of the evidence. CAS also formalizes argumentation schemes. Schemes can be used to check whether a given argument instantiates the types of argument deemed normatively appropriate for the type of dialogue.

In Biro and Siegel we argued that a theory of argumentation mustfully engage the normativity of judgments about arguments, and we developedsuch a theory. In this paper we further develop and defend our theory.

Synthese: An International Journal for Epistemology, Logic and Philosophy of Science, 157, 2007, 197-240. Published version available at: http://www.springerlink.com/content/q9402gv46t415504/fulltext.pdf.

This paper compares current ways of modeling the inferential structure of practical reasoning arguments, and proposes a new approach in which it is regarded in a modular way. Practical reasoning is not simply seen as reasoning from a goal and a means to an action using the basic argumentation scheme. Instead, it is conceived as a complex structure of classificatory, evaluative, and practical inferences, which is formalized as a cluster of three types of distinct and interlocked argumentation schemes. Using two (...) real examples, we show how applying the three types of schemes to a cluster of practical argumentation allows an argument analyst to reconstruct the tacit premises presupposed and evaluate the argumentative reasoning steps involved. This approach will be shown to overcome the limitations of the existing models of practical reasoning arguments within the BDI and commitment theoretical frameworks, providing a useful tool for discourse analysis and other disciplines. In particular, applying this method brings to light the crucial role of classification in practical argumentation, showing how the ordering of values and preferences is only one of the possible areas of deep disagreement. (shrink)

This article consists of three parts, two introductory, in which the limits and the methods of analysis of dialogues are expounded, and the major part, in which the main features of a philosophical theory of disputation are outlined.It was an essential aim of the philosophical analysis of argumentative dialogues to develop tools of substantiation for cases in which logic doesn't help any more. In the first part of this paper I show that such tools can and will be developed only (...) by analyzing argumentations (“argumentation” in the sense of a monologue in which arguments for a thesis are brought forward), and that the analysis of argumentative dialogues doesn't contribute anything to the development of such tools.The systematically first task of the philosophical analysis of dialogues consists in understanding the general practical aims of philosophically interesting types of dialogue. Only subsequently the rules of the dialogue can be reconstructed as good means for reaching these aims. Dialogical games constructed without referring to such a purpose are externally senseless and useless.The third part is an outline of a philosophical theory of disputation (“disputation” here will mean: (learned) dialogue in which the participants cooperatively though perhaps controversially attempt to find out by means of arguments and mutual criticism whether a thesis is true or false). Disputations contain argumentations, and many functions of a disputation can also be fulfilled by argumentations alone. Certifying the truth of convictions is the specific aim of disputation. This is accomplished by eliminating errors of substantiation and foundation as effectively as possible, in revising false convictions and their foundations, thereby making the remaining convictions more certain. Based on this analysis of the aim of disputation, the basic rules of disputations will be critically reconstructed: possible moves, rules of sequence, and the internal aim and ends of disputations. (shrink)

The article outlines a general epistemological theory of argument: a theory that regards providingjustified belief as the principal aim of argumentation, and defends it instrumentalistically. After introducing some central terms of such a theory, answers to its central questions are proposed: the primary object and structure of the theory, the function of arguments, which is to lead to justified belief, the way such arguments function, which is to guide the addressee's cognizing, objective versus subjective aspects of argumentation, designing different types (...) of argument. Then the notion of ' valid argument' is defined and criteria for the adequate use of such arguments are introduced. Finally, this conception is justified as, among others, leading to more true beliefs than competing conceptions. (shrink)

Pascal‘s wager is expounded as a paradigm case of a practical,decision-theoretical argument for acting as if a proposition is true when wehave no theoretical reasons to accept or reject it (1.1.–1.2.). Thoughthe paradigm is fallacious in various respects there are valid and adequatearguments for acting as if certain propositions are true: that theoreticalentities exist, that there are material perceptual objects, that the worldis uniform across time (1.3). After this analysis of examples the author‘sgeneral approach for developing criteria for the validity (...) and adequacy oftypes of argument (2.1.) is applied: Having discussed some problems(2.2.–2.3.), a general epistemic principle for such ’pascal arguments‘is developed, which characterizes their premisses and, if introduced as anadditional premiss, can make them deductively valid (2.4). (shrink)

In this paper an empirical theory about the nature of intention is sketched. After stressing the necessity of reckoning with intentions in philosophy of action a strategy for deciding empirically between competing theories of intention is exposed and applied for criticizing various philosophical theories of intention, among others that of Bratman. The hypothesis that intentions are optimality beliefs is defended on the basis of empirical decision theory. Present empirical decision theory however does not provide an empirically satisfying elaboration of the (...) desirability concepts used in these optimality beliefs. Based on process theories of deliberation two hypotheses for filling this gap are developed. (shrink)

Grennan bases his evaluation of arguments on two criteria: logical adequacy and pragmatic adequacy. He asserts that the common formal logic systems, while logically sound, are not very useful for evaluating everyday inferences, which are almost all deductively invalid as stated. Turning to informal logic, he points out that while more recent informal logic and critical thinking texts are superior in that their authors recognize the need to evaluate everyday arguments inductively, they typically cover only inductive fallacies, ignoring the inductively (...) sound patterns frequently used in successful persuasion. To redress these problems, Grennan introduces a variety of additional inductive patterns. Concluding that informal logic texts do not encourage precision in evaluating arguments, Grennan proposes a new argument evaluation procedure that expresses judgments of inferential strength in terms of probabilities. Based on theories of Stephen Toulmin, Roderick Chisholm, and John Pollock, his proposed system allows for a more precise judgment of the persuasive force of arguments. (shrink)

The evaluation of arguments and argumentation is best understood epistemologically. Epistemic circularity is not formally defective but it may be epistemologically objectionable. Sorenson's doubts about the syntactic approach to circularity are endorsed with qualifications. One explanation of an argument's goodness is its ability to produce justified belief in its conclusion by means of justified belief in its premises, but matters are not so simple for interpersonal argumentation. Even when an argument's premises and conclusion are justified for a speaker, this justifiedness (...) may not be transmissible to every hearer. Still, an epistemic approaeh is instructive. Arguing in enthymemes can be legitimate, e.g., because enthymemes can help produce justified persuasion in an audience that supplies the missing premises. (shrink)

There are distinct but legitimate notions of both personal justification and interpersonal justification. Interpersonal justification is definable in terms of personal justification. A connection is established between good argumentation and interpersonal justification.

This paper begins a working through of Blair’s (2001) theoretical agenda concerning argumentation schemes and their attendant critical questions, in which we propose a number of solutions to some outstanding theoretical issues. We consider the classification of schemes, their ultimate nature, their role in argument reconstruction, their foundation as normative categories of argument, and the evaluative role of critical questions.We demonstrate the role of schemes in argument reconstruction, and defend a normative account of their nature against specific criticisms due to (...) Pinto (2001). Concerning critical questions, we propose an account on which they are founded in the R.S.A. cogency standard, and develop an account of the relationship between critical questions and burden of proof. Our ultimate aim is to initiate a reconciliation between dialectical and informal logic approaches to the schemes. (shrink)

This book provides a systematic analysis of many common argumentation schemes and a compendium of 96 schemes. The study of these schemes, or forms of argument that capture stereotypical patterns of human reasoning, is at the core of argumentation research. Surveying all aspects of argumentation schemes from the ground up, the book takes the reader from the elementary exposition in the first chapter to the latest state of the art in the research efforts to formalize and classify the schemes, outlined (...) in the last chapter. It provides a systematic and comprehensive account, with notation suitable for computational applications that increasingly make use of argumentation schemes. (shrink)

Decision theory and the theory of rational choice have recently been the subjects of considerable research by philosophers and economists. However, no adequate anthology exists which can be used to introduce students to the field. This volume is designed to meet that need. The essays included are organized into five parts covering the foundations of decision theory, the conceptualization of probability and utility, pholosophical difficulties with the rules of rationality and with the assessment of probability, and causal decision theory. The (...) editors provide an extensive introduction to the field and introductions to each part. (shrink)

The book also comes with an exhaustive array of study aids that enable the reader to monitor and enhance the learning process.

Although fallacies have been common since Aristotle, until recently little attention has been devoted to identifying and defining them. Furthermore, the concept of fallacy itself has lacked a sufficiently clear meaning to make it a useful tool for evaluating arguments. Douglas Walton takes a new analytical look at the concept of fallacy and presents an up-to-date analysis of its usefulness for argumentation studies. Walton uses case studies illustrating familiar arguments and tricky deceptions in everyday conversation where the charge of fallaciousness (...) is at issue. The numerous case studies show in concrete terms many practical aspects of how to use textual evidence to identify and analyze fallacies and to evaluate arguments as fallacious. Walton looks at how an argument is used in the context of conversation. He defines a fallacy as a conversational move, or sequence of moves, that is supposed to be an argument that contributes to the purpose of the conversation but in reality interferes with it. The view is a pragmatic one, based on the assumption that when people argue, they do so in a context of dialogue, a conventionalized normative framework that is goal-directed. Such a contextual framework is shown to be crucial in determining whether an argument has been used correctly. Walton also shows how examples of fallacies given in the logic textbooks characteristically turn out to be variants of reasonable, even if defeasible or questionable arguments, based on presumptive reasoning. This is the essence of the evaluation problem. A key thesis of the book, which must not be taken for granted as previous textbooks have so often done, is that you can spot a fallacy from how it was used in a context of dialogue. This is an innovative and even, as Walton notes, "a radical and controversial" theory of fallacy. (shrink)

A leading expert in informal logic, Douglas Walton turns his attention in this new book to how reasoning operates in trials and other legal contexts, with special emphasis on the law of evidence. The new model he develops, drawing on methods of argumentation theory that are gaining wide acceptance in computing fields like artificial intelligence, can be used to identify, analyze, and evaluate specific types of legal argument. In contrast with approaches that rely on deductive and inductive logic and rule (...) out many common types of argument as fallacious, Walton’s aim is to provide a more expansive view of what can be considered "reasonable" in legal argument when it is construed as a dynamic, rule-governed, and goal-directed conversation. This dialogical model gives new meaning to the key notions of relevance and probative weight, with the latter analyzed in terms of pragmatic criteria for what constitutes plausible evidence rather than truth. (shrink)

A new pragmatic approach, based on the latest developments in argumentation theory, analyzing appeal to expert opinion as a form of argument. Reliance on authority has always been a common recourse in argumentation, perhaps never more so than today in our highly technological society when knowledge has become so specialized—as manifested, for instance, in the frequent appearance of "expert witnesses" in courtrooms. When is an appeal to the opinion of an expert a reasonable type of argument to make, and when (...) does it become a fallacy? This book provides a method for the evaluation of these appeals in everyday argumentation. Specialized domains of knowledge such as science, medicine, law, and government policy have gradually taken over as the basis on which many of our rational decisions are made daily. Consequently, appeal to expert opinion in these areas has become a powerful type of argument. Challenging an argument based on expert scientific opinion, for example, has become as difficult as it once was to question religious authority. Walton stresses that even in cases where expert opinion is divided, the effect of it can still be so powerful that it overwhelms an individual's ability to make a decision based on personal deliberation of what is right or wrong in a given situation. The book identifies the requirements that make an appeal to expert opinion a reasonable or unreasonable argument. Walton's new pragmatic approach analyzes that appeal as a distinctive form of argument, with an accompanying set of appropriate critical questions matching the form. Throughout the book, a historical survey of the key developments in the evolution of the argument from authority, dating from the time of the ancients, is given, and new light is shed on current problems of "junk science" and battles between experts in legal argumentation. (shrink)

Develops a logical analysis of dialogue in which two or more parties attempt to advance their own interests. It includes a classification of the major types of dialogues and a discussion of several important informal fallacies.

This book provides a systematic analysis of many common argumentation schemes and a compendium of 96 schemes. The study of these schemes, or forms of argument that capture stereotypical patterns of human reasoning, is at the core of argumentation research. Surveying all aspects of argumentation schemes from the ground up, the book takes the reader from the elementary exposition in the first chapter to the latest state of the art in the research efforts to formalize and classify the schemes, outlined (...) in the last chapter. It provides a systematic and comprehensive account, with notation suitable for computational applications that increasingly make use of argumentation schemes. (shrink)

This is an introductory guide to the basic principles of constructing good arguments and criticizing bad ones. It is nontechnical in its approach, and is based on 150 key examples, each discussed and evaluated in clear, illustrative detail. The author explains how errors, fallacies, and other key failures of argument occur. He shows how correct uses of argument are based on sound argument strategies for reasoned persuasion and critical questions for responding. Among the many subjects covered are: techniques of posing, (...) replying to, and criticizing questions, forms of valid argument, relevance, appeals to emotion, personal attack, uses and abuses of expert opinion, problems in deploying statistics, loaded terms, equivocation, and arguments from analogy. (shrink)

The basic question of this monograph is: how should we go about judging arguments to be reasonable or unreasonable? Our concern will be with argument in a broad sense, with realistic arguments in natural language. The basic object will be to engage in a normative study of determining what factors, standards, or procedures should be adopted or appealed to in evaluating an argument as "good," "not-so-good," "open to criticism," "fallacious," and so forth. Hence our primary concern will be with the (...) problems of how to criticize an argument, and when a criticism is reasonably justified. (shrink)

Presumption is a remarkably versatile and pervasively useful resource. Firmly grounded in the law of evidence from its origins in classical antiquity, it made its way in the days of medieval scholasticism into the theory and practice of disputation and debate. Subsequently, it extended its reach to play an increasingly significant role in the philosophical theory of knowledge. It has thus come to represent a region where lawyers, debaters, and philosophers can all find some common around. In Presumption and the (...) Practices of Tentative Cognition, Nicholas Rescher endeavors to show that the process of presumption plays a role of virtually indispensable utility in matters of rational inquiry and communication. The origins of presumption may lie in law, but its importance is reinforced by its service to the theory of information management and philosophy. (shrink)

This is an introductory 2001 textbook on probability and induction written by one of the world's foremost philosophers of science. The book has been designed to offer maximal accessibility to the widest range of students and assumes no formal training in elementary symbolic logic. It offers a comprehensive course covering all basic definitions of induction and probability, and considers such topics as decision theory, Bayesianism, frequency ideas, and the philosophical problem of induction. The key features of this book are a (...) lively and vigorous prose style; lucid and systematic organization and presentation of ideas; many practical applications; a rich supply of exercises drawing on examples from such fields as psychology, ecology, economics, bioethics, engineering, and political science; numerous brief historical accounts of how fundamental ideas of probability and induction developed; and a full bibliography of further reading. (shrink)

Knowledge plays an important role in argumentation. Yet, recent work shows that standard conceptions of knowledge in epistemology may not be entirely suitable for argumentation. This paper explores the role of knowledge in argumentation, and proposes a notion of knowledge that promises to be more suitable for argumentation by taking account of: its dynamic nature, the defeasibility of our commitments, and the non-monotonicity of many of the inferences we use in everyday reasoning and argumentation.

In this article, a new, idealizing-hermeneutic methodological approach to developing a theory of philosophical arguments is presented and carried out. The basis for this is a theory of ideal philosophical theory types developed from the analysis of historical examples. According to this theory, the following ideal types of theory exist in philosophy: 1. descriptive-nomological, 2. idealizing-hermeneutic, 3. technical-constructive, 4. ontic-practical. These types of theories are characterized in particular by what their basic types of theses are. The main task of this (...) article is then to determine the types of arguments that are suitable for justifying these types of theses. Surprisingly, practical arguments play a key role here. (shrink)

The article develops and justifies, on the basis of the epistemological argumentation theory, two central pieces of the theory of evaluative argumentation interpretation: 1. criteria for recognizing argument types and 2. rules for adding reasons to create ideal arguments. Ad 1: The criteria for identifying argument types are a selection of essential elements from the definitions of the respective argument types. Ad 2: After presenting the general principles for adding reasons (benevolence, authenticity, immanence, optimization), heuristics are proposed for finding missing (...) reasons, for deductive arguments, e.g., semantic tableaux are suggested. (shrink)