When someone is asked to speak his mind, it is sometimes possible for him to furnish what his utterance appears to have omitted. In such cases we might say that he had a mind to speak. Sometimes, however, the opposite is true. Asked to speak his mind, our speaker finds that he has no mind to speak. When it is possible to speak one's mind and when not is largely determined by the kinds of beings we are and by the (...) kinds of resources we are able to draw upon. In either case, not speaking one's mind is leaving something out whose articulation would or could matter for the purposes for which one was speaking in the first place. Inarticulation is no fleetingly contingent and peripheral phenomenon in human thinking and discourse. It is a substantial and dominant commonplace. In Part One I attempt to say something about what it is about the human agent that makes inarticulateness so rife. In Part Two, I consider various strategies for making the unarticulated explicit, and certain constraints on such processes. I shall suggest, among other things, that standard treatments of enthymematic reconstruction are fundamentally misconceived. (shrink)

E. C. W. Krabbe characterizes a metadialogue as a dialogue about a dialogue, which in turn, is characterized as a ground level dialogue. Krabbe raises a number of interesting questions about this distinction, of which the most pressing is whether the difference between ground level and metadialogues can be drawn in a principled and suitably general way. In this note, I develop the idea that something counts as a metadialogue to the extent that it stands to its ground level counterpart (...) in a relation of irrelevance. The irrelevance in question subsumes a triple of subconcepts: strategic relevance, agenda-relevance and irredundancy-relevance. (shrink)

Contemporary theory of argumentation offers many insights about the ways in which, in the context of a public controversy, arguers should ideally present their arguments and criticize those of their opponents. We also know that in practice not all works out according to the ideal patterns: numerous kinds of derailments are an object of study for argumentation theorists. But how about the use of unfairstrategiesvis-à-vis one’s opponents? What if it is not a matter of occasional derailments but of one party’s (...) systematic refusal to take other parties seriously? What if one party continually forgoes any form of critical testing and instead resorts to threats or blackmail? Can this be countered by the tools of reason? Or should one pay one’s opponent back in the same coin? To gain some grasp of these issues, we describe a number of strategies used in the public controversy about induced earthquakes in Groningen. We check whether these strategies arefair,i.e.balanced, transparent,andtolerant.We also investigate the effects of the choice for a particular kind of strategy. It appears that, in circumstances, choosing a fair strategy may be detrimental for resolving the controversy and choosing an unfair one beneficial. Following up ideas from social psychology and political science, we formulate some guidelines for the choice of strategies. At the end, we stress the importance — especially for those whose opinions carry little weight — of having a society in which the knowledge and skills needed for assessing the fairness of strategies are widespread. (shrink)

In all three of its manifestations, —abusive, circumstantial and tu quoque—the role of the ad hominem is to raise a doubt about the opposite party’s casemaking bona-fides.Provided that it is both presumptive and provisional, drawing such a conclusion is not a logical mistake, hence not a fallacy on the traditional conception of it. More remarkable is the role of the ad hominem retort in seeking the reassurance of one’s opponent when, on the face of it, reassurance is precisely what he (...) would seem to be ill-placed to give. Brief concluding remarks are given over to an examination of rival approaches to the ad hominem, especially those in which it is conceived of as a dialectical error. (shrink)

Formal dialogue systems model rule-based interaction between agents and as such have multiple applications in multi-agent systems and AI more generally. Their conceptual roots are in formal theories of natural argumentation, of which Hamblin’s formal systems of argumentation in Hamblin (Fallacies. Methuen, London, 1970, Theoria 37:130–135, 1971) are some of the earliest examples. Hamblin cites the medieval theory of obligationes as inspiration for his development of formal argumentation. In an obligatio, two agents, the Opponent and the Respondent, engage in an (...) alternating-move dialogue, where the Respondent’s actions are governed by certain rules, and the goal of the dialogue is establishing the consistency of a proposition. We implement obligationes in the formal dialogue system framework of Prakken (Knowl Eng Rev 21(2):163–188, 2006) using Dynamic Epistemic Logic (van Ditmarsch et al. in Dynamic epistemic logic, Synthese Library Series. Springer, Berlin, 2007). The result is a new type of inter-agent dialogue, for consistency-checking, and analyzing obligationes in this way also sheds light on interpretational and historical questions concerning their use and purpose in medieval academia. (shrink)

Enthymemes are traditionally defined as arguments in which some elements are left unstated. It is an empirical fact that enthymemes are both enormously frequent and appropriately understood in everyday argumentation. Why is it so? We outline an answer that dispenses with the so called "principle of charity", which is the standard notion underlying most works on enthymemes. In contrast, we suggest that a different force drives enthymematic argumentation—namely, parsimony, i.e. the tendency to optimize resource consumption, in light of the agent's (...) goals. On this view, the frequent use of enthymemes does not indicate sub-optimal performance of arguers, requiring appeals to charity for their redemption. On the contrary, it is seen as a highly adaptive argumentation strategy, given the need of everyday reasoners to optimize their cognitive resources. Considerations of parsimony also affect enthymeme reconstruction, i.e. the process by which the interpreter makes sense of the speaker's enthymemes. Far from being driven by any pro-social cooperative instinct, interpretative efforts are aimed at extracting valuable information at reasonable costs from available sources. Thus, there is a tension between parsimony and charity, insofar as the former is a non-social constraint for self-regulation of one's behaviour, whereas the latter implies a pro-social attitude. We will argue that some versions of charity are untenable for enthymeme interpretation, while others are compatible with the view defended here, but still require parsimony to expose the ultimate reasons upon which a presumption of fair treatment in enthymeme reconstruction is founded. (shrink)

This paper studies general numerical networks with support and attack. Our starting point is argumentation networks with the Caminada labelling of three values 1=in, 0=out and ½=undecided. This is generalised to arbitrary values in [01], which enables us to compare with other numerical networks such as predator?prey ecological networks, flow networks, logical modal networks and more. This new point of view allows us to see the place of argumentation networks in the overall landscape of networks and import and export ideas (...) to and from argumentation networks. We make a special effort to make clear how general concepts in general networks relate to the special case of argumentation networks. We pay special attention to the handling of loops and to the special features of numerical support. We find surprising connections with the Dempster?Shafer rule and with the cross-ratio in projective geometry. This paper is an expansion of our 2005 paper and so we also consider higher level features such as numerical attacks on attacks, and propagation of numerical values.We conclude with a brief view of temporal numerical argumentation and with a detailed comparison with related papers published since 2005. (shrink)

This volume presents mathematical game theory as an interface between logic and philosophy.

The quality of our public discourse – think of the climate change debate for instance – is never very high. A day spent observing it reveals a litany of misrepresentation and error, argumentative fallacy, and a general lack of good will. In this paper I focus on a microcosmic aspect of these practices: the use of two types of argument – the argumentum ad hominem and appeal to authority – and a way in which they are related. Public debate is (...) so contaminated by the misuse of the ad hominem tactic that it is important to have an understanding of one of the ways in which its use may be legitimate. So readers who might have expected an analysis of the ad hominem fallacy will, on the contrary, be presented with an account of one of the places for its potential success. In ad hominem, arguers are viewed as legitimate constitutive targets for their own argument; in authority arguments, arguers provide a legitimate constitutive warrant for an argument they deploy. These types of argument are connected in so far as the identities of persons deploying them carry the cognitive weight of the argument. If authority arguments sometimes deserve to succeed, ad hominem attacks on them are potentially legitimate. An important motivation for this analysis is that in identifying the success conditions for one of the ad hominem types we attain some clarity in the evaluation of their use. (shrink)

Why are enthymemes so frequent? Are we dumb arguers, smart rhetoricians, or parsimonious reasoners? This paper investigates systematic use of enthymemes, criticizing the application of the principle of charity to their interpretation. In contrast, I propose to analyze enthymematic argumentation in terms of parsimony, i.e. as a manifestation of the rational tendency to economize over scant resources. Consequences of this view on the current debate on enthymemes and on their rational reconstruction are discussed.