There is no concept more central to logic and critical thinking than the concept of an argument. I here address the definition of ‘argument’ in the logical sense of the term and defend the claim that many current proposals, once they are interpreted in a way that makes them sufficiently precise, are extensionally inadequate. Definitions found in some contemporary, prominent critical thinking textbooks will serve as a springboard. I claim that each may be interpreted in an absolutist way or a (...) relativistic way, yet all turn out to be objectionable no matter which route is taken. I finish with a proposal on which the definition of ‘argument’ is an absolutist one, yet one that avoids the problems discussed for the earlier proposals. (shrink)

The development of symbolic logic is often presented in terms of a cumulative story of consecutive innovations that led to what is known as modern logic. This narrative hides the difficulties that this new logic faced at first, which shaped its history. Indeed, negative reactions to the emergence of the new logic in the second half of the nineteenth century were numerous and we study here one case, namely logic at Oxford, where one finds Lewis Carroll, a mathematical teacher who (...) promoted symbolic logic, and John Cook Wilson, the Wykeham Professor of Logic who notoriously opposed it. An analysis of their disputes on the topic of logical symbolism shows that their opposition was not as sharp as it might look at first, as Cook Wilson was not so much opposed to the « symbolic » character of logic, but the intrusion of mathematics and what he perceived to be the futility of some of its problems, for logicians and philosophers alike. (shrink)

Although in some contexts the notions of an ordinary argument’s presumption, assumption, and presupposition appear to merge into the one concept of an implicit premise, there are important differences between these three notions. It is argued that assumption and presupposition, but not presumption, are basic logical notions. A presupposition of an argument is best understood as pertaining to a propositional element (a premise or the conclusion) e of the argument, such that the presupposition is a necessary condition for the truth (...) of e or for a term in e to have a referent. In contrast, an assumption of an argument pertains to the argument as a whole in that it is integral to the reasoning or inferential structure of the argument. A logical assumption of an argument is essentially a proposition that must be true in order for the argument aside from that proposition to be fully cogent. Nothing that is both comparable and distinguishing can be said about presumptions of arguments. Rather, presumptions of arguments are distinctively conventional; they are introduced through conventional rules (e.g., those that concern how to treat promises). So not all assumptions and not all presuppositions of arguments are presumptions of those arguments, although all presumptions of arguments are either assumptions or presuppositions of those arguments. This account avoids making the (monological) notion of presumption vacuous and dissolving the distinction between assumption and presumption, which is a vulnerability of alternative views such as Hansen’s and Bermejo-Luque’s, as is shown. (shrink)

The paper sheds light on an important procedural debate in the U.S. House of Representatives on the American Federal Bill of Rights in the summer of 1789. To study the debate, it is proposed that it is useful to draw on the informal fallacy of ad socordiam, and an illustration is provided, with attention paid to the question of how to identify and analyze the fallacy.

This discussion is grounded in Aristotelian–Thomistic realism and takes the position that nursing is a practical science. As an exposition of the title statement, distinctions are made between opinion and truth, and the speculative, productive and practical sciences. Sources of opinion and truth are described and a discussion follows that truth can be achieved through knowing principles and causes of the natural kind behind phenomena. It is proposed that humans are the natural kind behind nursing phenomena. Thus, human nature provides (...) proper principles (the truth) of nursing practice. (shrink)

In this paper I develop an account of petitio principii (the fallacy sometimes also called ‘vicious circularity’, or ‘begging the question’) which has two crucial features: it employs the notion of doxastic justification, and it takes circularity to be relative to an evidential state. According to my account, an argument will be circular relative to an evidential state if and only if having doxastic justification for the conclusion is necessary, for a subject in that evidential state, to have doxastic justification (...) for the premisses. I compare the account to some existing ones, and claim some advantages. I then rebut an objection which threatens to undermine the importance of one of those advantages. This account seems to shed new light on the old problem of characterizing petitio principii. It avoids the two obvious problems which any account of this phenomenon must face: being too narrow, for example by leaving out all arguments in which the conclusion does not appear among the premisses, and being too wide, making all valid arguments circular. (shrink)

Against the background of the fact that speakers not seldom intend to convey imports which deviate from the linguistically expressed meanings of linguistic items, the present article addresses some consequences of this phenomenon which appear to still be neglected in textual studies. It is suggested that understanding behaviour is in some respect a primary objective of exegesis and that due attention must be attributed to the high diversity of behaviour-related criteria by which interpretations of linguistic items are to be evaluated. (...) Although we intimate in addition that individual (meaningful) sentences occurring either in oral conversations or in written documents generally exhibit a multiplicity of contents of diverse types and that the circumstance that sometimes only a content equalling the linguistic significance of a pertinent unit matters for purposes of interpretation is caused by a material coincidence of different varieties of content, the tenets advocated in the paper do not essentially depend on that view. On the other hand, the following assumptions are relevant in the present connection: (a) A number of deviances between imports conveyed by linguistic utterances and literal meanings of expressions occur due to maxims of linguistic behaviour that are quite independent of lexical and syntactic features of individual natural languages. (b) It is by no means an exceptional phenomenon that imports not derivable by grammatical rules of a particular language alone possess primary importance for interpretation and textual exegesis. In view of significant affinities between understanding of sentences and of texts it is argued that the consideration of diverse aspects of behaviour possesses relevance for textual exegesis at least in the following respects: (1) By delivering a heuristic device for discerning problems affecting adopted interpretations it encourages searches for alternatives. (2) It provides means for evaluating the degree of acceptability of particular textual exegeses and possibly rejecting them on a more rational basis than mere intuition. (3) It offers possibilities for critically assessing the validity of explicit arguments advanced in favour of or in opposition to some interpretation. (4) It furnishes a background for assessing certain disputes about translation. The dimension of linguistic behaviour also attains importance in connection with questions of exegesis which are not concerned with assessments of (propositional) contents intended to be communicated, such as the ascertainment of the function which some argument possesses in a context. For substantiating the thesis that omission of raising relevant questions concerning behaviour is not an isolated phenomenon two examples will be employed: (1) A discussion concerning the exegesis of a crucial passage of Dignāga’s Pramāṇasamuccaya and the Pramāṇasamuccayavṛtti, (2) a critical appraisal of a recent publication dealing with the interpretation of the second chapter of Nāgārjuna’s Mūlamadhyamakakārikā-s. (shrink)

We argue that Hilary Putnam's pragmatism provides an epistemological perspective which can help us understand--and can positively inform--the development of informal logic.

Stewart Cohen considers a case where his son wants a red table for his room. Cohen and his son go to the furniture store. Cohen’s son is concerned that the table his father is considering purchasing, which appears red, may in fact be white with red lights shining on it. Cohen responds with the following reasoning: The table looks red. The table is red. If the table is red, then it is not white with red lights shining on it. The (...) table is not white with red lights shining on it. If one reasons thus, say one’s engaged in -reasoning. Cohen finds such a response unsatisfactory. It is not a way of coming to know —it is too easy. And structurally similar reasoning delivers the falsity of sceptical hypotheses concerning the external world, testimony, other minds etc. So the unsatisfactoriness threatens to generalise. I consider Martin Davies ’s attempt to diagnose this unsatisfactoriness and find it incomplete. I then attempt to remedy the incompleteness in Davies ’s attempt. (shrink)

Abstract In this essay, I will argue that images can play a substantial role in argumentation: exploiting information from the context, they can contribute directly and substantially to the communication of the propositions that play the roles of premises and conclusion. Furthermore, they can achieve this directly, i.e. without the need of verbalization. I will ground this claim by presenting and analyzing some arguments where images are essential to the argumentation process. Content Type Journal Article Pages 1-14 DOI 10.1007/s10503-011-9259-y Authors (...) Axel Arturo Barceló Aspeitia, Instituto de Investigaciones Filosóficas, Universidad Nacional Autónoma de México, Cto. Mario de la Cueva s/n, Cd. Universitaria, Coyoacán, 04500 DF, Mexico Journal Argumentation Online ISSN 1572-8374 Print ISSN 0920-427X. (shrink)

If one looks to the current textbook lore for reliable taxonomic and analytical information about the petitio principii, one is met with conceptual disarray and much too much nonsense. The present writers have recently attempted to furnish the beginnings of a theoretical reconstruction of this fallacy which is at once faithful to its formidable complexity yet useful as guide for its detection and avoidance. The fact is that the petitio has had a lengthy and interesting history, and in this paper (...) we shall want to explore certain features of its development, such as it may have been. The principal origins of the concept of circular argument are to be found in Aristotle. The Aristotelian doctrine recurs with variations in the sophismata literature of the middle ages and in logic texts and manuals right up to the present day. (shrink)

The main stream of formal and informal logic as well as more recent work in discourse analysis provides a way of understanding certain arguments that particularly lend themselves to rational analysis. I argue, however, that these, and allied modes of analysis, be seen as heuristic models and not as the only proper mode of argument. This article introduces three other modes of argumen tation that emphasize distinct aspects of human communication, but that, at the same time, must be considered for (...) the full understanding of argumentation. These modes are (1) the emotional, which relates to the realm of feelings, (2) the visceral, which stems from the area of the physical, and (3) the kisceral, which covers the intuitive and non-sensory arenas. At its most extreme the view holds that arguments may be given (almost) wholly within one mode and not be at all susceptible to those methods of argument analysis previously used. A more cautious statement allows that any interactive argument will (possibly) contain elements from various modes, and that to attempt to reduce these all to the rational is prejudiced reductionism. (shrink)

The structuralist heritage in linguistics continues to obscure the essential properties of natural language as an empirical phenomenon. It is argued that the new framework of autopoiesis possesses a greater explanatory power, as it assumes the connotational na-ture of language. The key notions of representation, sign and signification, interpreta-tion, intentionality and communication, and reciprocal causality, approached from the autopoietic angle, allow for deeper insights into the essence of language which is as a kind of adaptive behavior of an organism involving (...) a system constituted by signs of signs. (shrink)

In this paper, we introduce the notion of dual Post’s negation and an infinite class of Dual Post’s finitely-valued logics which differ from Post’s ones with respect to the definitions of negation and the sets of designated truth values. We present adequate natural deduction systems for all Post’s k-valued ) logics as well as for all Dual Post’s k-valued logics.

Jim Mackenzie; Authority, Journal of Philosophy of Education, Volume 22, Issue 1, 30 May 2006, Pages 57–65, https://doi.org/10.1111/j.1467-9752.1988.tb00177.x.

I argue that there is no fallacy of argument from authority. I first show the weakness of the case for there being such a fallacy: text-book presentations are confused, alleged examples are not genuinely exemplary, reasons given for its alleged fallaciousness are not convincing. Then I analyse arguing from authority as a complex speech act. Rejecting the popular but unjustified category of the "part-time fallacy", I show that bad arguments which appeal to authority are defective through breach of some felicity (...) condition on argument as a speech act, not through employing a bad principle of inference. (shrink)

In addition to the distinction between species as a category and speciesas a taxon, the word species is ambiguous in a very different butequally important way, namely the temporal distinction between horizontal andvertical species. Although often found in the relevant literature, thisdistinction has thus far remained vague and undefined. In this paper the use ofthe distinction is explored, an attempt is made to clarify and define it, andthen the relation between the two dimensions and the implications of thatrelation are examined. (...) Using Darwin's analogy of language evolution forspeciesevolution, and by appealing to a major change in the conception of languagebetween 19th- and 20th-century linguistics, it is argued that the horizontaldimension has priority (pragmatic, epistemological, logical, and ontological)over the vertical dimension. This has immense ramifications for the modernspecies problem. Fundamentally, it favors horizontal species concepts oververtical ones. In so doing it places species realism on a much more securefoundation and largely undercuts species pluralism. In addition it raises aserious problem for the increasingly popular family of phylogenetic speciesconcepts, which generally suffer from a dimensionality confusion. However,thereis a recent trend within this family that attempts to restore the priority ofthe horizontal dimension. It is concluded that this trend should be affirmedandthat the species-as-individuals view should be abandoned. (shrink)

This paper looks at the need for a better understanding of the impediments to critical thinking in relation to graduate student work. The paper argues that a distinction is needed between two vectors that influence student writing: (1) the word-level–sentence-level vector; and (2) the grammar–inferencing vector. It is suggested that much of the work being done to assist students is only done on the first vector. This paper suggests a combination of explicit use of deductive syllogistic inferences and computer-aided argument (...) mapping is needed. A methodology is suggested for tackling assignments that require students to ‘make an argument’. It is argued that what lecturers understand tacitly, now needs to be made a focus of deliberate educational practices. (shrink)

Donepezil, an acetylcholinesterase inhibitor used in the treatment of Alzheimer's disease, has been widely cited in media and bioethics literature on cognitive enhancement (CE) as having the potential to improve the cognitive ability of healthy individuals. In both literatures, this claim has been repeatedly supported by the results of a small study published by Yesavage et al. in 2002 on non-demented pilots (30-70 years old). The factors contributing to this specific interpretation of this study's results are unclear.

A critical examination of the dialectical approach, focusing on a comparison ofthe illative and the dialectical definitions of argument. I distinguish a moderate, a strong and a hyper dialectical conception of argument. I critique Goldman's argument for the moderate conception and Johnson's argument for the strong conception, and argue that the moderate conception is correct.

This article analyses the fallacy of wrenching from context, using the dialectical notions of commitment and implicature as tools. The data, a set of key examples, is used to sharpen the conceptual borderlines around the related fallacies of straw man, accent, misquotation, and neglect of qualifications. According to the analysis, the main characteristics of wrenching from context are the manipulation of the meaning of the other’s statement through devices such as the use of misquotations, selective quotations, and quoting out of (...) context. The theoretical tools employed in the analysis are pragmatic theories of meaning and a dialectical model of commitment, used to explain how and why a standpoint is distorted. The analysis is based on a conception of fallacies as deceptive strategic moves in a game of dialogue. As a consequence, our focus is not only on misquotations as distortions of meaning, but on how they are used as dialectical tools to attack an opponent or win a dispute. Wrenching from context is described as a fallacy of unfairly attributing a commitment to another party that he never held. Its power as a deceptive argumentation tactic is based on complex mechanisms of implicit commitments and on their misemployment to improperly suggest an attribution of commitment. (shrink)

Bayesian probability has recently been proposed as a normative theory of argumentation. In this article, we provide a Bayesian formalisation of the ad Hitlerum argument, as a special case of the ad hominem argument. Across three experiments, we demonstrate that people's evaluation of the argument is sensitive to probabilistic factors deemed relevant on a Bayesian formalisation. Moreover, we provide the first parameter-free quantitative evidence in favour of the Bayesian approach to argumentation. Quantitative Bayesian prescriptions were derived from participants' stated subjective (...) probabilities (Experiments 1 and 2), as well as from frequency information explicitly provided in the experiment (Experiment 3). Participants' stated evaluations of the convincingness of the argument were well matched to these prescriptions. (shrink)

RésuméCet article discute diverses confusions, actueles ou potentielles, liées á la bivalence et au tiers exclu. Il s'agit, en particulier, 1) d'examiner divers cas illustrant les rapports entre la bivalence et le tiers exclu ; 2) de discuter la thése selon laquelle le tiers exclu et le schéma-T de Tarskipour la vérité entraînent la bivalence; 3) de proposer quelques remarques sur les rapports entre la bivalence, le tiers exclu et la preuve par l'absurde; 4) de scruter un argument répandu selon (...) lequel le tiers exclu vaut pour les termes «précis» et 5) de commenter l'histoire de la terminologie. L'objectif ici est d'attirer l'attention des philosophes sur une distinction importante qui ne reçoit pas souvent le traitement minutieux qu'elle mérite. (shrink)

In lieu of an abstract, here is a brief excerpt of the content:Philosophy and Rhetoric 34.2 (2001) 93-112 [Access article in PDF] Enthymemes, Common Knowledge, and Plausible Inference Douglas Walton The study of enthymemes has always been regarded as important in logic, critical thinking, and rhetoric, but too often it is the formal or mechanistic aspect of it that has been in the forefront. This investigation will show that there is a kind of plausibilistic script-based reasoning, of a kind that (...) has mainly been studied in artificial intelligence, that should have a much more important role to play in the study of enthymemes. But then curiously, as will also be shown, this plausibilistic type of reasoning was familiar in the ancient world, to the Sophists, as well as to leading philosophers such as Plato and Aristotle. By linking this ancient notion of plausibility to the modern notion used in computer science, this investigation reveals an important basis for the enthymeme that has a type of logical structure in its own right, but also has an informal aspect.An enthymeme, in current usage, is an argument that has one or more premises, or possibly a conclusion, not explicitly stated in the text, but that needs to have these propositions explicitly stated to extract the complete argument from the text. Sometimes enthymemes are described as arguments with "missing premises." That vocabulary is awkward, however, because the nonexplicit statement that needs to be added can be a conclusion, at least in a minority of cases. To make the exposition below smoother, the term nonexplicit assumption will be used to cover either the case of a nonexplicit premise or that of a nonexplicit conclusion. The problem with enthymemes is that if the nonexplicit assumptions in an argument are supposed to be propositions used by the arguer (as opposed to just the propositions needed to make the argument structurally correct, according to some standard), reasonable people can have differences of opinion on what the nonexplicit assumptions are supposed to be. The problem is that filling in the missing parts of enthymemes depends on interpreting the natural language [End Page 93] in which the argument was put forward to try to determine what the speaker meant to say.The solution to the problem comes through the recognition that enthymemes rest not only on formal (structural) criteria, but also on informal criteria. One of the most important of these informal criteria is something often called "common knowledge" (Govier 1992; Freeman 1995). But as shown below in a set of selected case studies of enthymemes, "common knowledge" is not really a kind of knowledge at all. It is really plausibility, or eikos, something well known in the ancient world and often misleadingly translated as "probability." Curiously, Aristotle's original doctrine of the enthymeme was based on this notion of plausibility. This historical fact has often been a source of puzzlement and confusion, and sometimes it has even been taken to indicate a defect or contradiction in Aristotle's treatment of the enthymeme. However, the goal of this investigation is not primarily historical. It is to work out one of the most important required steps toward a solution to the problem of enthymemes. But to do this, it is necessary to come back to the ancient notion of plausible inference. 1. The problem with enthymemes Once you have any formal theory of inference, like syllogistic, for example, you will be confronted by cases of arguments in everyday discourse that meet all the requirements for a structurally correct inference except that some part or parts, usually a premise or a conclusion, is missing. By "missing" is meant that the proposition in question has not been explicitly stated in the text of discourse, even though it may be clear enough that the speaker (writer) was relying on it, or including it, as part of the argument. The classic example is the following inference: All men are mortal; therefore, Socrates is mortal. To evaluate such an argument, surely some account of the "hidden" or "missing" assumption needs to be taken. The problem with enthymemes (Burke 1985; Gough and Tindale 1985; Hitchcock 1985) is that, if given carte... (shrink)

Coalescent argumentation is a normative ideal that involves the joining together of two disparate claims through recognition and exploration of opposing positions. By uncovering the crucial connection between a claim and the attitudes, beliefs, feelings, values and needs to which it is connected dispute partners are able to identify points of agreement and disagreement. These points can then be utilized to effect coalescence, a joining or merging of divergent positions, by forming the basis for a mutual investigation of non-conflictual options (...) that might otherwise have remained unconsidered. The essay proceeds by defining and discussing ‘argument’, ‘position’ and ‘understanding’. These notions are then brought together to outline the concept of coalescent reasoning. (shrink)

The main finding of a comprehensive empirical research project on the intersubjective acceptability of the pragma-dialectical discussion rules (Van Eemeren, Garssen & Meuffels, 2009) is that ordinary language users judge discussion moves that are considered fallacious from an argumentation-theoretical perspective as unreasonable. In light of this finding it is remarkable that in everyday argumentative discourse fallacies occur regularly and seem many times not to be noticed by the participants in the discourse. This also goes for the abusive argumentum ad hominem. (...) While abusive ad hominem attacks are judged to be very unreasonable discussion moves when the unreasonableness of clear cases of this fallacy is rated in experiments, in real life this fallacy remains undetected more often than not. In this paper it is argued that this paradox can be explained by analysing abusive ad hominem attacks as a mode of strategic manoeuvring which takes on a reasonable appearance in real life situations when it mimics, as it often does, legitimate critical reactions to authority argumentation. The hypothesis that abusive fallacies are seen as less unreasonable when they are presented as if they are critical questions pertaining to the argument scheme for authority argumentation than when they are clear cases was tested systematically in two experiments. The results of these experiments confirmed the hypothesis. (shrink)

I characterize the deductivist ideal of justification and, following to a great extent Toulmin’s work The Uses of Argument, I try to explain why this ideal is erroneous. Then I offer an alternative model of justification capable of making our claims to knowledge about substantial matters sound and reasonable. This model of justification will be based on a conception of justification as the result of good argumentation, and on a model of argumentation which is a pragmatic linguistic reconstruction of Toulmin’s (...) model of argument. (shrink)

Over the past 60 years there have been tremendous advances made in Argumentation Theory. One crucial advance has been the move from the investigation of static arguments to a concern with dialogic interactions in concrete contexts. This focus has entailed a slow shift toward involving both non-logical and non-discursive elements in the analysis of an argument. I argue that the traditional attitude Informal Logic has displayed toward emotion can be and ought be moderated. In particular, I examine the role of (...) emotion in everyday argumentation, and how Informal Logic can encompass it alongside the more traditional logical mode of communication. (shrink)

In this work the concept of 'context' is considered in five main points. First, context is seen as always necessary for an adequate explication of the concepts of meaning and understanding. Context always plays a role and is not merely brought into consideration when handling a special class of statements or terms, or when there is doubt and clarification is necessary. Second, context cannot be completely reduced to some system of representation. The reason for this is the presence of humans, (...) which is always an important component of a context. Humans experience situations in ways that are not always reducible to symbolic representation. Third, contexts are in principle open. In normal cases they cannot be determined or described in advance. A context is not to be equated with a set of information. Fourth, we understand the parameters of a context pragmatically, which is why we are not led into doubt or even to meaning skepticism by the open nature of a context. This pragmatic knowledge belongs to the category of an ability. Fifth, contexts are, in principle, accessible. This denies the idea that some contexts are incommensurable. There are a number of pragmatic ways of accessing unfamiliar contexts. Some of these are here examined in light of the so-called 'culture wars' in the U.S.A. (shrink)

In a posthumous paper, Perelman discusses his decision to bring his theory of argumentation together with rhetoric rather than calling it an informal logic. This is due in part because of the centrality he gives to audience, and in part because of the negative attitude that informal logicians have to rhetoric. In this paper, I explore both of these concerns by way of considering what benefits Perelman’s work can have for informal logic, and what insights the work of informal logicians (...) might bring to the project of Perelman and Olbrechts-Tyteca. (shrink)

This discussion is grounded in Aristotelian–Thomistic realism and takes the position that nursing is a practical science. As an exposition of the title statement, distinctions are made between opinion and truth, and the speculative, productive and practical sciences. Sources of opinion and truth are described and a discussion follows that truth can be achieved through knowing principles and causes of the natural kind behind phenomena. It is proposed that humans are the natural kind behind nursing phenomena. Thus, human nature provides (...) proper principles (the truth) of nursing practice. (shrink)

This paper describes an approach to legal logic based on the formal analysis of argumentation schemes. Argumentation schemes a notion borrowed from the .eld of argumentation theory - are a kind of generalized rules of inference, in the sense that they express that given certain premises a particular conclusion can be drawn. However, argumentation schemes need not concern strict, abstract, necessarily valid patterns of reasoning, but can be defeasible, concrete and contingently valid, i.e., valid in certain contexts or under certain (...) circumstances. A method is presented to analyze argumentation schemes and it is shown how argumentation schemes can be embedded in a formal model of dialectical argumentation. (shrink)

Argument by analogy has long been regarded as the characteristic way of arguing in ancient Chinese culture. Classic Chinese philosophers not only prefer to use analogy to argue for their own views, but also take efforts to theorize it in a systematic way. This paper aims to provide a careful study on the relevant ideas in ancient China in order to reconstruct the ancient Chinese theory of argument by analogy, and then to reveal some of its distinctive features through a (...) comparison with the Western counterpart account as developed by Aristotle. It is indicated that in ancient China analogical argument was conceived primarily as a way of arguing based on classification, with a unique mechanism of taking and giving according to kind. On that basis, it is argued that although such a characterization captures the logical structure of analogical argument in a similar way to Aristotle, the ancient Chinese theory stresses the foundational role of a particular notion of kind, thus makes the construction and application of analogical arguments become highly flexible and context-sensitive. Moreover, it is also contended that in ancient China the rationale of analogical arguments is explained from a general perspective of kind, relying upon the universal knowledge pertaining to the forming of kinds. Then it is further revealed that, unlike Aristotle who emphasizes the causal links between attributes in the physical world, ancient Chinese thinkers justify analogical argument by appealing to some normative metaphysical and epistemological principles. (shrink)

B. Kooi and A. Tamminga present a correspondence analysis for extensions of G. Priest’s logic of paradox. Each unary or binary extension is characterizable by a special operator and analyzable via a sound and complete natural deduction system. The present paper develops a sound and complete proof searching technique for the binary extensions of the logic of paradox.

In studying logic, one learns how to establish that a conclusion follows from a set of premises. Those arguments that exhibit one of the valid forms of the deductive system under study are valid. There may be questions about what forms are exhibited by various arguments - Is this English conditional really truth-functional? Is this disjunction really inclusive? Are the English predicates used with uniform meaning? - but none of these problems undermine the claim that if an argument exhibits a (...) valid form of a system for deductive logic, then that argument is valid.When we move on to study invalidity, however, we find that the situation is not parallel. Every argument is an instance of some invalid argument forms, and we cannot say that every instance of every invalid form is invalid. (shrink)

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

This essay examines Maduabuchi Dukor’s perspective on the African conception of man, personal identity and“life-here-after”. This is with a view to showing that although, Dukor’s views represent what obtain among some ethnic nationalities in Africa, this nevertheless does not provide a basis for generalising across the whole of Africa, as there are countless number of ethnic groups in Africa to which Dukor’s general claims may not be applicable. Given the varieties of metaphysical conceptions of man and destiny in Africa which (...) we are yet to fully explore, and given also the inherent contradictions in some of these conceptions, which calls into questioning, the veracity of claims made therein, it will amount to a major logical error to make sweeping generalisations that would be representative of the whole of Africa. Such generalisations would remain a non-holistic, but partial representation of the African conception of man and human destiny. (shrink)

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

The argument by analogy for other minds is customarily rejected as a weak inference because the argument is based on a single instance. The current paper argues that this objection fundamentally misunderstands the inferential structure of analogies and so misrepresents the role analogy plays in the justifycation of belief in other minds. Arguments by be uniquely suited to draw inferences from single instances. This defense does not remove all difficulties faced by the argument by analogy for other minds.

Identifying the missing or unstated premisses of arguments is important, because their logical quality depends on them. Textbook authors regard enthymematic syllogisms (e.g., "Elvis is a man, so Elvis is mortal") as having an unstated premiss - the major premiss (e.g., "All men are mortal"). They are said to be such because these syllogisms become formally valid when the major premiss is added (i.e., it is a gap-filler). I argue that unstated major premises are not gap-fillers: they support a part (...) of the argument that is already given implicitly - the inference claim ("If the premisses are true then the conclusion is true"). As such, their logical status is the same as that of an unstated proposition that supports the minor premiss, which is not part of the argument. Therefore, the so-called "major premiss" is not an unstated premiss of the enthymeme. (shrink)

Intuitionism and nihilism, according to nihilists, have key features in common: the same semantics and the same phenomenology. Intuitionism is the object of nihilism’s attack. The central charge nihilism lodges against intuitionism is that its nonnatural moral properties are queer. Here I’ll examine what ‘queer’ might mean in relation to the doctrines nihilism uses to support this charge. My investigation reveals that nihilism’s queerness charge lacks substance and resembles a tautology served with a frown. There’s really nothing to it. After (...) I show that, I’ll offer an explanation for why nihilism has gotten intuitionism wrong. It makes a central mistaken methodological assumption and doesn’t target any identifiable intuitionism in the last hundred or so years. (shrink)