The paper offers a critical analysis of the research program for formalizing informal logic proposed by Douglas Walton and Thomas Gordon. Since their proposal is based on employing the Carneades Argumentation System, this paper aims at answering two questions: what are main benefits of applying CAS as means for formalizing informal logic, and what are possible extensions of Walton and Gordon’s research program and modifications in employing CAS?

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)

Plausible (eikotic) reasoning known from ancient Greek (late Academic) skeptical philosophy is shown to be a clear notion that can be analyzed by argumentation methods, and that is important for argumentation studies. It is shown how there is a continuous thread running from the Sophists to the skeptical philosopher Carneades, through remarks of Locke and Bentham on the subject, to recent research in artificial intelligence. Eleven characteristics of plausible reasoning are specified by analyzing key examples of it (...) recognized as important in ancient Greek skeptical philosophy using an artificial intelligence model called the Carneades Argumentation System (CAS). By applying CAS to ancient examples it is shown how plausible reasoning is especially useful for gaining a better understanding of evidential reasoning in law, and argued that it can also be applied to everyday argumentation. Our analysis of the snake and rope example of Carneades is also used to point out some ways CAS needs to be extended if it is to more fully model the views of this ancient philosopher on argumentation. (shrink)

In this paper, the Carneades argumentation system is extended to represent a procedural view of inquiry in which evidence is marshalled to support or defeat claims to knowledge. The model is a sequence of moves in a collaborative group inquiry in which parties take turns making assertions about what is known or not known, putting forward evidence to support them, and subjecting these moves to criticisms. It is shown how this model of evaluating evidence in an inquiry (...) is based on a defeasible logic using forms of argument that admit exceptions. It is contended that reasoning from absence of knowledge is as important to inquiry as positive reasoning from evidence to knowledge. The philosophical conflict between this view of reasoning about knowledge and the true-belief-plus view is explored by airing objections and replies on both sides. (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)

Because motives and intentions are internal, and not directly observable by another agent, it has always been a problem to find a pathway of reasoning linking them to externally observable evidence. This paper proposes an argumentation-based method that one can use to support or attack hypotheses about the motives or intentions of an intelligent autonomous agent based on verifiable evidence. The method is based on a dialectical argumentation approach along with a commitment-based theory of mind. It is implemented (...) using the Carneades Argumentation System, which already has 106 programmed schemes available to it and has an argument search tool. The method uses schemes, notably ones for abductive reasoning, argument from action to intention, argument from action to motive, and some new ones. (shrink)

Abstract This paper addresses the role that argumentation schemes and argument visualization software tools can play in helping to find and counter objections to a given argument one is confronted with. Based on extensive analysis of features of the argumentation in these two examples, a practical four-step method of finding objections to an argument is set out. The study also applies the Carneades Argumentation System to the task of finding objections to an argument, and shows (...) how this system has some capabilities that are especially useful. Content Type Journal Article Pages 1-23 DOI 10.1007/s10503-012-9261-z Authors Douglas Walton, Centre for Research in Reasoning, Argumentation and Rhetoric (CRRAR), University of Windsor, 2500 University Ave. W., Windsor, ON N9B 3Y1, Canada Journal Argumentation Online ISSN 1572-8374 Print ISSN 0920-427X. (shrink)

It can be said that the roots of the studies on the argumentation theory go back to rhetorical and dialectical studies. One of the sub-fields of the argumentation theory is argument schemes, used in everyday language and various fields within certain rules. Today, with the studies in the field of informal logic, argumentation schemes have aslo become an important field to study. The argumentation schemes approach also plays an important role in the study of artificial language (...) at the intersection of the computer science area. In this article, we discussed Douglas Walton’s argumentation schemes approach. Douglas Walton's aim is to determine the natural language arguments used in various fields and make as a list of them and propose a classification for argumentation schemes. Douglas Walton, presents a model for the argumentation schemes. This model also emphasized the structure suitable for use in computer systems. Determination, analysis and evaluation of arguments are important topics for the arguments applying to computer systems. In this article, we discuss one of these systems, Thomas Gordon’s project, the Carneades Argumentation System. The Carneades Argumentation System is a system which can handle Douglas Walton's argumentation schemes. With the Carneades Argumentation System, it is possible to visualize arguments as an argument map. The visualization of an argumentation provides a concrete basis for philosophical discussions. It makes it easy for the user to determine the scheme of the current argument when applying the argument formats to mapping and evaluation systems such as Carneades Argumentation Systems. Determining the argument scheme allows the argument to be handled within a particular model. The aim of this article is to discuss the argumentation schemes which is one of the topics of study at the intersection of philosophical logic and computer sciences in which informal logic studies are developing today. (shrink)

Multimorbidity, the presence of multiple health conditions that must be addressed, is a particularly difficult situation in patient management raising issues such as the use of multiple drugs and drug-disease interactions. Clinical Guidelines are evidence-based statements which provide recommendations for specific health conditions but are unfit for the management of multiple co-occurring health situations. To leverage these evidence-based documents, it becomes necessary to combine them. In this paper, using a case example, we explore the use of argumentation schemes to (...) reason and combine evidence-based recommendations from clinical guidelines, expected effects, conflicts stemming from said recommendations, and preferences regarding treatment goals. We compare the results of reasoning using the schemes for practical reasoning and argument from negative consequences in the Carneades Argumentation System with those of ASPIC-G, an extension of the artificial intelligence system ASPIC+. (shrink)

Even though tools for identifying and analyzing arguments are now in wide use in the field of argumentation studies, so far there is a paucity of resources for evaluating real arguments, aside from using deductive logic or Bayesian rules that apply to inductive arguments. In this paper it is shown that recent developments in artificial intelligence in the area of computational systems for modeling defeasible argumentation reveal a different approach that is currently making interesting progress. It is shown (...) how these systems provide the general outlines for a system of argument evaluation that can be applied to legal arguments as well as everyday conversational arguments to assist a user to evaluate an argument. (shrink)

Tribunals have come to depend increasingly on expertise for determining the facts in cases. However, current legal methods have proved problematic to work with. This paper argues that, as a special model of public understanding of science, assessing expertise should consider source credibility of expertise from internal aspects, including scientific validity and reliability, and external aspects involving the credibility of experts. Using the Carneades Argumentation System we show that the internal and the external aspects are mediated by (...) the structure of the argument from expert opinion with its matching set of critical questions. (shrink)

This paper compares the features and methods of the two leading implemented systems that offer a tool for helping a user to find or invent arguments to support or attack a designated conclusion, the Carneades Argumentation System and the IBM Watson Debater tool. The central aim is to contribute to the understanding of scholars in informal logic, rhetoric and argumentation on how these two software systems can be useful for them. One contribution of the paper is (...) to explain to these potential users how the two tools are applicable to the task of inventing arguments by using some simple illustrative examples. Another is to redefine the structure of argument invention as a procedure. (shrink)

This paper proposes an argumentation-based procedure for legal interpretation, by reinterpreting the traditional canons of textual interpretation in terms of argumentation schemes, which are then classified, formalized, and represented through argument visualization and evaluation tools. The problem of statutory interpretation is framed as one of weighing contested interpretations as pro and con arguments. The paper builds an interpretation procedure by formulating a set of argumentation schemes that can be used to comparatively evaluate the types of arguments used (...) in cases of contested statutory interpretation in law. A simplified version of the Carneades Argumentation System is applied in a case analysis showing how the procedure works. A logical model for statutory interpretation is finally presented, covering pro-tanto and all-things-considered interpretive conclusions. (shrink)

This paper applies recent work on scripts and stories developed as tools of evidential reasoning in artificial intelligence to model the use of argument from analogy as a rhetorical device of persuasion. The example studied is Gerry Spence’s closing argument in the case of Silkwood v. Kerr-McGee Corporation, said to be the most persuasive closing argument ever used in an American trial. It is shown using this example how argument from analogy is based on a similarity premise where similarity between (...) two cases is modeled using the device of a story scheme from the hybrid theory of legal evidential reasoning (Bex in Arguments, stories and criminal evidence: a formal hybrid theory. Springer, Dordrecht 2011). It is shown how the rhetorical strategy of Spence’s argumentation in the closing argument interweaves argument from analogy with explanation through three levels. (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.

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.

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)

We present a formal, mathematical model of argument structure and evaluation, taking seriously the procedural and dialogical aspects of argumentation. The model applies proof standards to determine the acceptability of statements on an issue-by-issue basis. The model uses different types of premises (ordinary premises, assumptions and exceptions) and information about the dialectical status of statements (stated, questioned, accepted or rejected) to allow the burden of proof to be allocated to the proponent or the respondent, as appropriate, for each premise (...) separately. Our approach allows the burden of proof for a premise to be assigned to a different party than the one who has the burden of proving the conclusion of the argument, and also to change the burden of proof or applicable proof standard as the dialogue progresses from stage to stage. Useful for modeling legal dialogues, the burden of production and burden of persuasion can be handled separately, with a different responsible party and applicable proof standard for each. Carneades enables critical questions of argumentation schemes to be modeled as additional premises, using premise types to capture the varying effect on the burden of proof of different kinds of questions. (shrink)

We developed an on-line intelligent argumentation system which facilitates stakeholders in exchanging dialogues. It provides decision support by capturing stakeholders’ rationale through arguments. As part of the argumentation process, stakeholders tend to both polarise their opinions and form polarisation groups. The challenging issue of assessing argumentation polarisation had not been addressed in argumentation systems until recently. Arvapally, Liu, and Jiang [, ‘Identification of Faction Groups and Leaders in Web-Based Intelligent Argumentation System for Collaborative (...) Decision Support’, in Proceedings of International Conference on Collaborative Technologies and Systems] earlier developed a method to identify polarisation groups. These groups, however, tend to overlap to a certain degree; each stakeholder may be a member of multiple polarisation groups to varied degrees. Quantifying stakeholders’ membership in multiple polarisation groups is an important issue in the argumentation for collaborative decision-making, which is not addressed earlier. We present a novel approach using fuzzy clustering algorithm to address this issue in this article. The method is evaluated using data sets produced from the discussions of 24 stakeholders. Experimental results indicate that our method is effective for both identifying polarisation groups and quantifying stakeholders’ degree of membership in each polarisation group. (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. Carneades 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.

This paper shows how the critical questions matching an argumentation scheme can be mod-eled in the Carneades argumentation system as three kinds of premises. Ordinary premises hold only if they are supported by sufficient arguments. Assumptions hold, by default, until they have been questioned. With exceptions the negation holds, by default, until the exception has been supported by sufficient arguments. By “sufficient arguments”, we mean arguments sufficient to satisfy the applicable proof standard.

In this paper we introduce a formalism for single-agent decision making that is based on Dynamic Argumentation Frameworks. The formalism can be used to justify a choice, which is based on the current situation the agent is involved. Taking advantage of the inference mechanism of the argumentation formalism, it is possible to consider preference relations, and conflicts among the available alternatives for that reasoning. With this formalization, given a particular set of evidence, the justified conclusions supported by warranted (...) arguments will be used by the agent’s decision rules to determine which alternatives will be selected. We also present an algorithm that implements a choice function based on our formalization. Finally, we complete our presentation by introducing formal results that relate the proposed framework with approaches of classical decision theory. (shrink)

In this paper we show that an essential aspect of solving the problem of uncritical acceptance of expert opinions that is at the root of the ad verecundiam fallacy is the need to disentangle argument from expert opinion from another kind of appeal to authority. Formal and computational argumentation systems enable us to analyze the fault in which an error has occurred by virtue of a failure to meet one or more of the requirements of the argumentation scheme (...) from argument from expert opinion. We present a method for enhancing this capability by showing how arguments from expert opinion are related to, but different from, arguments from deontic authority. (shrink)

Dealing with complex problems often requires argumentative skills that go beyond the natural abilities even of gifted students and lecturers. We sketch how to reconstruct and evaluate arguments and outline how the fostering of argumentative skills is integrated into the curriculum in Environmental Sciences at the Department of Environmental Systems Sciences of ETH Zurich.

In his works on argumentation, Aristotle develops three main forms: apodeictical, dialectical, and rhetorical argumentation; dialectic is subdivided into several subspecies. The purpose of this paper is to discuss all of the forms described by Aristotle, to examine their differences and to point out their interrelations. This leads to an examination of the differentiating criteria and their applicability in the case of each argumentation form—and in particular to the question regarding the number of criteria that are necessary (...) to describe each form clearly and unambiguously. It is argued that Aristotle’s works on argumentation contain an implicit system of argumentation forms that is based on no more than three criteria. (shrink)

As genetic testing for the presence of potentially health-affecting mutations becomes available for more genetic conditions, many people will soon be faced with the decision of whether or not to have a genetic test. Making an informed decision requires an understanding and evaluation of the arguments for and against having the test. As a case in point, this paper considers argumentation involving the decision of whether to have a BRCA gene test, one of the first commercially available genetic tests. (...) First, argumentation in a five-page patient brochure from a for-profit company that provides BRCA gene testing, is analyzed. Next, for comparison, argumentation on BRCA testing in materials for healthcare consumers written by a not-for-profit health plan and a government organization, is analyzed. In view of the challenges identified by considering these examples, this article discusses how argumentation-oriented computer systems may be able to help the healthcare consumer to make informed decisions about genetic testing. (shrink)

Safe Safety arguments are key components in a safety case. Too often, safety arguments are constructed without proper reasoning. To address this, we argue that informal logic argument schemes have important roles to play in safety argument construction and reviewing process. Ten commonly used reasoning schemes in computer system safety domain are proposed. The role of informal logic dialogue games in computer system safety arguments reviewing is also discussed and the intended work in this area is proposed. It (...) is anticipated that this work will contribute toward the development of computer system safety arguments, and help to move forward the interplay between research in informal logic and research in computer system safety engineering. (shrink)

In this paper we provide a proof theoretical investigation of logical argumentation, where arguments are represented by sequents, conflicts between arguments are represented by sequent elimination rules, and deductions are made by dynamic proof systems extending standard sequent calculi. The idea is to imitate argumentative movements in which certain claims are introduced or withdrawn in the presence of counter-claims. This is done by a dynamic evaluation of sequences of sequents, in which the latter are considered ‘derived’ or ‘not derived’ (...) according to the content of the sequence. We show that decisive conclusions of such a process correspond to well-accepted consequences of the underlying argumentation framework. The outcome is therefore a general and modular proof-theoretical approach for paraconsistent and non-monotonic reasoning with argumentation systems. (shrink)

This paper explains the importance of classifying argumentation schemes, and outlines how schemes are being used in current research in artificial intelligence and computational linguistics on argument mining. It provides a survey of the literature on scheme classification. What are so far generally taken to represent a set of the most widely useful defeasible argumentation schemes are surveyed and explained systematically, including some that are difficult to classify. A new classification system covering these centrally important schemes is (...) built. (shrink)

Alternative dispute resolution occurs outside the litigation process. The alternative dispute resolution (ADR) movement in North America has emphasized viable alternatives to the litigation framework, such as arbitration, mediation, med-arb, multi-party facilitation, non-legal negotiation, mini-trials, administrative hearings, private judging (“renta-judge”), fact finding, and moderated settlement conferences. This essay addresses argument in the dominant alternatives: arbitration, mediation, and multi-party facilitation. Prior to comparing argument in these ADR systems, each will be briefly described.

The paper discusses the role of systemic means of persuasion in argument evaluation. The core class of systemic means of persuasion is regress stoppers, whose fundamental function is to halt the infinite regress of justification by making claims, premises, or overall position expressed in a persuasive message more acceptable to a recipient. The paper explores how systemic means of persuasion contribute to the structure of arguments in the Toulmin model and serve as cues for heuristic processing of persuasive messages. It (...) also presents the results of the stylometric analysis and statistical data on the usage of systemic means of persuasion in three corpora which suggest that systemic means of persuasion constitute strategies independent of the strategy based on explicit argumentation marked by inference indicators. (shrink)

This paper explains the importance of classifying argumentation schemes, and outlines how schemes are being used in current research in artificial intelligence and computational linguistics on argument mining. It provides a survey of the literature on scheme classification. What are so far generally taken to represent a set of the most widely useful defeasible argumentation schemes are surveyed and explained systematically, including some that are difficult to classify. A new classification system covering these centrally important schemes is (...) built. (shrink)

We describe and analyze an important cognitive obstacle in inter- and intra-community ar-gumentation processes, which we propose to call 'Cognitive Systemic Dichotomization'. This social phenomenon consists in the collective use of shared cognitive patterns based upon dichotomous schemati-zation of knowledge, values, and affection. We discuss the formative role of CSD on a community’s collec-tive cognition, identity, and public discourse, as well as the challenges it raises to reasoned argumentation, and how different approaches to argumentation undertake to face this (...) obstacle to the reasonable debate of issues of public concern. (shrink)

Society is becoming increasingly reliant upon the dependability of computerbased systems. Achieving and demonstrating the dependability of systems requires the construction and review of valid and coherent arguments. This paper discusses the need for a variety of classes of arguments in dependable systems and reviews existing approaches to the representation of arguments in each of these classes. The issues surrounding the certification of safety critical systems demonstrate the current need for richer representations of dependability arguments which support tools for their (...) construction and review. The paper discusses how a meta-logical framework, informed by aspects of both formal and informal logic, offers a rich and unified means of representing dependability arguments and of thus addressing this need. (shrink)

$${{{\mathcal {F}}}}$$ -systems are useful digraphs to model sentences that predicate the falsity of other sentences. Paradoxes like the Liar and the one of Yablo can be analyzed with that tool to find graph-theoretic patterns. In this paper we studied this general model consisting of a set of sentences and the binary relation ‘ $$\ldots $$ affirms the falsity of $$\ldots $$ ’ among them. The possible existence of non-referential sentences was also considered. To model the sets of all the (...) sentences that can jointly be valued as true we introduced the notion of conglomerate, the existence of which guarantees the absence of paradox. Conglomerates also enabled us to characterize referential contradictions, i.e., sentences that can only be false under a classical valuation due to the interactions with other sentences in the model. A Kripke-style fixed-point characterization of groundedness was offered, and complete (meaning that every sentence is deemed either true or false) and consistent (meaning that no sentence is deemed true and false) fixed points were put in correspondence with conglomerates. Furthermore, argumentation frameworks are special cases of $$\mathcal{F}$$ -systems. We showed the relation between local conglomerates and admissible sets of arguments and argued about the usefulness of the concept for the argumentation theory. (shrink)

The paper reconstructs Luhmann’s conception of legal argumentation and justice especially focussing on the aspects of contingency and self-referring operative closure. The aim of his conception is to describe/explain in a disenchanted way—from an external, of “second order” point of view—the work on adjudication, which, rather idealistically, lawyers and judges present as being a matter of reason. As a consequence of some surface similarities with Derrida’s deconstructive philosophy of justice, Teubner proposes integrating the supposed reductive image of formal justice (...) described by Luhmann with the ideal conception of justice presented by Derrida. Here this kind of attempt is rejected as epistemologically wrong. In addition, Luhmann’s theory is argued to have other shortcomings, namely: the failure to understand the pragmatic function of principles, and the incapacity to describe the current legal questions linked with cultures and legal pluralism, which characterise our society. (shrink)

There are many benefits of using argumentation-based techniques in multi-agent systems, as clearly shown in the literature. Such benefits come not only from the expressiveness that argumentation-based techniques bring to agent communication but also from the reasoning and decision-making capabilities under conditions of conflicting and uncertain information that argumentation enables for autonomous agents. When developing multi-agent applications in which argumentation will be used to improve agent communication and reasoning, argumentation schemes (reasoning patterns for argumentation) (...) are useful in addressing the requirements of the application domain in regards to argumentation (e.g., defining the scope in which argumentation will be used by agents in that particular application). In this work, we propose an argumentation framework that takes into account the particular structure of argumentation schemes at its core. This paper formally defines such a framework and experimentally evaluates its implementation for both argumentation-based reasoning and dialogues. (shrink)

In this article we will consider the application of tense logics enriched with additional modal operators or additional logical values to construct logical systems in which the thesis of logical determinism cannot be expressed.

The paper discusses the role of systemic means of persuasion in argument evaluation. The core class of systemic means of persuasion is regress stoppers, whose fundamental function is to halt the infinite regress of justification by making claims, premises, or overall position expressed in a persuasive message more acceptable to a recipient. The paper explores how systemic means of persuasion contribute to the structure of arguments in the Toulmin model and serve as cues for heuristic processing of persuasive messages. It (...) also presents the results of the stylometric analysis and statistical data on the usage of systemic means of persuasion in three corpora which suggest that systemic means of persuasion constitute strategies independent of the strategy based on explicit argumentation marked by inference indicators. (shrink)

This paper explicates an account of argumentative rationality by articulating the common, basic idea of its nature, and then identifying a collection of assumptions inherent in it. Argumentative rationality is then contrasted with dual-process theories of reasoning and rationality prevalent in the psychology of reasoning. It is argued that argumentative rationality properly corresponds only with system-2 reasoning in dual-process theories. This result challenges the prescriptive force of argumentative norms derives if they derive at all from their descriptive accuracy of (...) our cognitive capacities. In response, I propose an activity-based account of reasoning which retains the assumptions of argumentative rationality while recontextualizing the relationship between reasoning as a justificatory activity and the psychological states and processes underlying that activity. (shrink)

There are many benefits of using argumentation-based techniques in multi-agent systems, as clearly shown in the literature. Such benefits come not only from the expressiveness that argumentation-based techniques bring to agent communication but also from the reasoning and decision-making capabilities under conditions of conflicting and uncertain information that argumentation enables for autonomous agents. When developing multi-agent applications in which argumentation will be used to improve agent communication and reasoning, argumentation schemes are useful in addressing the (...) requirements of the application domain in regards to argumentation. In this work, we propose an argumentation framework that takes into account the particular structure of argumentation schemes at its core. This paper formally defines such a framework and experimentally evaluates its implementation for both argumentation-based reasoning and dialogues. (shrink)

Historians of science have proposed many theories to explain why Copernicus rejected the Ptolemaic system and advanced his own heliocentric system. In support of his new cosmological system Copernicus always employed theoretical considerations and never the existence of discrepancies between the positions given in the Tables and those observed. It is shown that the general acceptance of the heliocentric system through the work of the astronomers resulted not so much from empirical considerations but rather from the (...) fact that this system was suited to a comprehensive, general dynamics. (shrink)

In this paper we describe an approach to practical reasoning, reasoning about what it is best for a particular agent to do in a given situation, based on presumptive justifications of action through the instantiation of an argument scheme, which is then subject to examination through a series of critical questions. We identify three particular aspects of practical reasoning which distinguish it from theoretical reasoning. We next provide an argument scheme and an associated set of critical questions which is able (...) to capture these features. In order that both the argument scheme and the critical questions can be given precise interpretations we use the semantic structure of an Action-Based Alternating Transition System as the basis for their definition. We then work through a detailed example to show how this approach to practical reasoning can be applied to a problem solving situation, and briefly describe some other previous applications of the general approach. In a second example we relate our account to the social laws paradigm for co-ordinating multi-agent systems. The contribution of the paper is to provide firm foundations for an approach to practical reasoning based on presumptive argument in terms of a well-known model for representing the effects of actions of a group of agents. (shrink)

Trust is a natural mechanism by which an autonomous party, an agent, can deal with the inherent uncertainty regarding the behaviours of other parties and the uncertainty in the information it shares with those parties. Trust is thus crucial in any decentralised system. This paper builds on recent efforts to use argumentation to reason about trust. Specifically, a set of schemes is provided, and abstract patterns of reasoning that apply in multiple situations geared towards trust. Schemes are described (...) in which one agent, A, can establish arguments for trusting another agent, B, directly, as well as schemes that A can use to construct arguments for trusting C, where C is trusted by B. For both sets of schemes, a set of critical questions is offered that identify the situations in which these schemes can fail. (shrink)

The paper develops a classificatory system of basic argument types on the basis of the epis-temological approach to argumentation. This approach has provided strict rules for several kinds of argu-ments. These kinds may be brought into a system of basic irreducible types, which rely on different parts of epistemology: deductive logic, probability theory, utility theory. The system reduces a huge mass of differ-ent argument schemes to basic types and gives them an epistemological foundation.

Argumentation schemes can be described as abstract structures representing the most generic types of argument, constituting the building blocks of the ones used in everyday reasoning. This paper investigates the structure, classification, and uses of such schemes. Three goals are pursued: 1) to describe the schemes, showing how they evolved and how they have been classified in the traditional and the modern theories; 2) to propose a method for classifying them based on ancient and modern developments; and 3) to (...) outline and show how schemes can be used to describe and analyze or produce real arguments. To this purpose, we will build on the traditional distinctions for building a dichotomic classification of schemes, and we will advance a modular approach to argument analysis, in which different argumentation schemes are combined together in order to represent each step of reasoning on which a complex argument relies. Finally, we will show how schemes are applied to formal systems, focusing on their applications to Artificial Intelligence, AI & Law, argument mining, and formal ontologies. (shrink)

In this paper we discuss the application of a new machine learning approach – Argument Based Machine Learning – to the legal domain. An experiment using a dataset which has also been used in previous experiments with other learning techniques is described, and comparison with previous experiments made. We also tested this method for its robustness to noise in learning data. Argumentation based machine learning is particularly suited to the legal domain as it makes use of the justifications of (...) decisions which are available. Importantly, where a large number of decided cases are available, it provides a way of identifying which need to be considered. Using this technique, only decisions which will have an influence on the rules being learned are examined. (shrink)