Expert reasoning is responsible for some of the most stunning human achievements, but also for some of the most disastrous decisions ever made. The argumentative theory of reasoning has proven very effective at explaining the pattern of reasoning’s successes and failures. In the present article, it is expanded to account for expert reasoning. The argumentative theory predicts that reasoning should display a strong confirmation bias. If argument quality is not sufficiently high in a domain, the confirmation bias will make experts (...) tap into their vast knowledge to defend whatever opinion they hold, with polarization and overconfidence as expected results. By contrast, experts should benefit even more from the power of group discussion to make the best of the confirmation bias—when they genuinely disagree that is, otherwise polarization is again likely to ensue. When experts interact with laymen other mechanisms can take the lead, in particular trust calibration and consistency checking. They can yield poor outcomes if experts do not have a sustained interaction with laymen, or if the laymen have strong opinions when they witness a debate between experts. Seeing reasoning as a mechanism of epistemic vigilance aimed at finding and evaluating arguments helps make better sense of expert reasoning performance, be it in individual ratiocination, in debates with other experts, or in interactions with laymen. (shrink)

Short abstract (98 words). Reasoning is generally seen as a means to improve knowledge and make better decisions. However, much evidence shows that reasoning often leads to epistemic distortions and poor decisions. This suggests that the function of reasoning should be rethought. Our hypothesis is that the function of reasoning is argumentative. It is to devise and evaluate arguments intended to persuade. Reasoning so conceived is adaptive given humans’ exceptional dependence on communication and vulnerability to misinformation. A wide range of (...) evidence in the psychology of reasoning and decision making can be reinterpreted and better explained in the light of this hypothesis. (shrink)

This book presents novel formalizations of three of the most important medieval logical theories: supposition, consequence and obligations. In an additional fourth part, an in-depth analysis of the concept of formalization is presented - a crucial concept in the current logical panorama, which as such receives surprisingly little attention.Although formalizations of medieval logical theories have been proposed earlier in the literature, the formalizations presented here are all based on innovative vantage points: supposition theories as algorithmic hermeneutics, theories of consequence analyzed (...) with tools borrowed from model-theory and two-dimensional semantics, and obligations as logical games. For this reason, this is perhaps the first time that these medieval logical theories are made fully accessible to the modern philosopher and logician who wishes to obtain a better grasp of them, but who has always been held back by the lack of appropriate ‘translations' into modern terms.Moreover, the book offers a reflection on the very nature of logic, a reflection that is prompted by the comparisons between medieval and modern logic, their similarities and dissimilarities. It is thus a contribution not only to the history of logic, but also to the philosophy of logic, the philosophy of language and semantics.The analysis of medieval logic is also relevant for the modern philosopher and logician in that, being the unifying methodology used across all disciplines at that time, logic really provided unity to science. It thus presents a unified model of scientific investigation, where logic plays the aggregating role. (shrink)

Two periods in the history of logic and philosophy are characterized notably by vivid interest in self-referential paradoxical sentences in general, and Liar sentences in particular: the later medieval period (roughly from the 12th to the 15th century) and the last 100 years. In this paper, I undertake a comparative taxonomy of these two traditions. I outline and discuss eight main approaches to Liar sentences in the medieval tradition, and compare them to the most influential modern approaches to such sentences. (...) I also emphasize the aspects of each tradition that find no counterpart in the other one. It is expected that such a comparison may point in new directions for future research on the paradoxes; indeed, the present analysis allows me to draw a few conclusions about the general nature of Liar sentences, and to identify aspects that would require further investigation. (shrink)

The focus of the paper is a sophism based on the proposition ‘This is Socrates’ found in a short treatise on obligational casus attributed to William Heytesbury. First, the background to the puzzle in Walter Burley’s traditional account of obligations (the responsio antiqua), and the objections and revisions made by Richard Kilvington and Roger Swyneshed, are presented. All six types of obligations described by Burley are outlined, including sit verum, the type used in the sophism. Kilvington and Swyneshed disliked the (...) dynamic nature of the responsio antiqua, and Kilvington proposed a revision to the rules for irrelevant propositions. This allowed him to use a form of reasoning, the “disputational meta-argument”, which is incompatible with Burley’s rules. Heytesbury explicitly rejected Kilvington’s revision and the associated meta-argument. Swyneshed also revised Burley’s account of obligations, formulating the so-called responsio nova, characterised by the apparently surprising thesis that a conjunction can be denied both of whose conjuncts are granted. On closer inspection, however, his account is found to be less radical than first appears. (shrink)

The paper argues that much of the difficulty with making progress on the issue of the normativity of logic for thought, as discussed in the literature, stems from a misapprehension of what logic is normative for. The claim is that, rather than mono-agent mental processes, logic in fact comprises norms for quite specific situations of multi-agent dialogical interactions, in particular special forms of debates. This reconceptualization is inspired by historical developments in logic and mathematics, in particular the pervasiveness of such (...) dialogical conceptions in the early days of logic in ancient Greece. The multi-agent, dialogical perspective then allows for the formulation of compelling 'bridge principles’ between the relation of logical consequence and dialogical normative principles, something that is notoriously difficult to achieve in a mono-agent setting pertaining exclusively to thought and belief. The upshot is also that the truth-preserving rules of logic generally do not have a primary normative bearing on mono-agent mental processes, and in this sense the paper sides with Harman's critique of the idea that logic has a normative import for thought and belief. (shrink)

Walter Sinnott-Armstrong argues that moral disagreement and widespread moral bias pose a serious problem for moral intuitionism. Seneca’s view that we just recognise the good could be criticised using a similar argument. His approach to argumentation offers a way out, one that may serve as a model for a revisionary intuitionism.

There is a deep tension between logical and probabilistic norms of belief. This article illustrates the normative force that is associated with these frameworks by showing how rather unrestricted belief bases can be improved by undergoing logical and probabilistic reflection. It is argued that probabilistic reasoning accounts for the reliability of the conclusions one can draw from the beliefs. Most importantly, reliability commands us to care for the increasing uncertainty of conjunctions of beliefs. Deductive logic captures the agent's commitment towards (...) all conclusions of her beliefs. In other words, it seems that commitment forces the agent to believe conclusions, which reliability tells her to view with scepticism. This conflict is resolved by arguing that commitment merely forces the agent to find the logical conclusions of her beliefs acceptable, not necessarily to believe them. This demands consistency but no deductive closure. Furthermore, it is shown that by restoring consistency, a straightforward connection between high subjective probability and full belief is undermined. Finally, the article delineates how this approach deals with the lottery paradox and the preface paradox. (shrink)

Mercier & Sperber (M&S) argue for their argumentative theory in terms of communicative abilities. Insights can be gained by extending the discussion beyond human reasoning to rodent and robot navigation. The selection of arguments and conclusions that are mutually reinforcing can be cast as a form of abductive reasoning that I argue underlies the construction of cognitive maps in navigation tasks.

In earlier work, I have presented an interpretation of Obligationes as logical games of consistency maintenance; this interpretation has some advantages, in particular that of capturing the multi-agent, goal-oriented, rule-governed nature of the enterprise by means of the game analogy. But it has as its main limitation the fact that it does not provide a satisfactory account of the deontic aspect of the framework—i.e. of what being obliged to a certain statement consists in. In order to remedy this shortcoming, this (...) paper argues for the more encompassing thesis that Obligationes can be viewed as a theory of rational dialogical practices, in particular concerning the management of one's discursive commitments. The main inspiration for this interpretation comes from R. Brandom's inferentialist, normative pragmatism, but more generally, it relies heavily on a dialogical conception of logic. I argue that it offers a more compelling account of several aspects of the obligational framework, in particular the role of doubting responses and the ubiquity of obligational vocabulary in the context of scientific discourse in the medieval tradition. (shrink)

In [Dutilh Novaes, Medieval-obligations as logical Games of Consistency maintenance, synthese, (2004)], I proposed a reconstruction of Walter Burley’s theory of obligationes, based on the idea that Burley’s theory of obligationes could be seen as a logical game of consistency maintenance. In the present paper, I intend to test the game hypothesis on another important theory of obligationes, namely Roger Swyneshed’s theory. In his treatise on obligationes [edited by P.V. Spade, cf. Spade History and philosophy of Logic 3(1982) 1-32], Swyneshed (...) introduced significant modifications to the general framework of obligationes. To compare the two theories, I apply the same formal apparatus used in the previous paper. It will become patent that Swyneshed’s theory is considerably different from Burley’s, among other reasons because the dynamic aspects that play a major role in the latter are simply not present in the former. My conclusion is that Swyneshed’s version of obligationes is not directed towards consistency maintenance, but rather towards inference recognition, and that it is, from a game-theoretical perspective, less interesting a theory than Burley’s. (shrink)

This thesis is on the history and philosophy of logic and semantics. Logic can be described as the ‘science of reasoning’, as it deals primarily with correct patterns of reasoning. However, logic as a discipline has undergone dramatic changes in the last two centuries: while for ancient and medieval philosophers it belonged essentially to the realm of language studies, it has currently become a sub-branch of mathematics. This thesis attempts to establish a dialogue between the modern and the medieval traditions (...) in logic, by means of ‘translations’ of the medieval logical theories into the modern framework of symbolic logic, i.e. formalizations. One of its conclusions is that, when properly understood within their own framework, the interest of medieval logical theories for modern investigations go beyond mere historical interest, but that a thorough conceptual analysis of such theories must be undertaken in order to avoid conceptual misprojections. While such translations of medieval into modern logic have been attempted before, the approach presented here is innovative in that attention is paid to the similarities as well as to the dissimilarities between the two traditions, and to what can be learned from the medieval masters for modern investigations in logic and semantics. (shrink)

Este artículo se propone reconstruir histórica y metodológicamente la disputatio scholastica y acercarse a la manera como era ejercitado este tipo de juego dialéctico en los colegios jesuitas de la América Hispánica. Examinando fuentes manuscritas e impresas, se enumeran y discuten las reglas que los participantes de los certámenes filosóficos de la escolástica barroca obedecían. La estructura lógica y dialéctica de la disputatio es examinada a la luz del método de discusión abstraído y sistematizado por Aristóteles en los Tópicos. Se (...) destaca el lugar privilegiado de la capacidad de distinguir sentidos como instrumento de la dialéctica en la disputatio scholastica. (shrink)

What role, if any, does dialectic play in Aristotle’s epistemology in the Topics? In this paper I argue that it does play a role, but a role that is independent of endoxa. In the first section, I sketch the case for thinking that dialectic plays a distinctively epistemological role—not just a methodological role, or a merely instrumental role in getting episteme. In the second section, I consider three ways it could play that role, on two of which endoxa play at (...) least a co-starring role. But in the third section, I argue that endoxa don’t play that co-starring role, by arguing for a deflationary account of what endoxa are. For that reason, the third view emerges as the most plausible; but the third view is, I’ll suggest, Platonic. (shrink)

Theoreticians of deliberative democracy have sometimes found it hard to relate to the seemingly contradictory experimental results produced by psychologists and political scientists. We suggest that this problem may be alleviated by inserting a layer of psychological theory between the empirical results and the normative political theory. In particular, we expose the argumentative theory of reasoning that makes the observed pattern of findings more coherent. According to this theory, individual reasoning mechanisms work best when used to produce and evaluate arguments (...) during a public deliberation. It predicts that when diverse opinions are discussed, group reasoning will outperform individual reasoning. It also predicts that individuals have a strong confirmation bias. When people reason either alone or with like-minded peers, this confirmation bias leads them to reinforce their initial attitudes, explaining individual and group polarization. We suggest that the failures of reasoning are most likely to be remedied at the collective than at the individual level. (shrink)

The article deals with the Lutheran–Catholic religious colloquy at Regensburg of 1601. It points out that the event was of importance not only for political and religious reasons but also in terms...

Mercier & Sperber (M&S) claim that the phenomenon of belief bias provides fundamental support for their argumentative theory and its basis in intuitive judgement. We propose that chronometric evidence necessitates a more nuanced account of belief bias that is not readily captured by argumentative theory.