Nonmonotonic conditionals (A |∼ B) are formalizations of common sense expressions of the form “if A, normally B”. The nonmonotonic conditional is interpreted by a “high” coherent conditional probability, P(B|A) > .5. Two important properties are closely related to the nonmonotonic conditional: First, A |∼ B allows for exceptions. Second, the rules of the nonmonotonic system p guiding A |∼ B allow for withdrawing conclusions in the light of new premises. This study reports a series of three experiments on (...) class='Hi'>reasoning with inference rules about nonmonotonic conditionals in the framework of coherence. We investigated the cut, and the right weakening rule of system p. As a critical condition, we investigated basic monotonic properties of classical (monotone) logic, namely monotonicity, transitivity, and contraposition. The results suggest that people reason nonmonotonically rather than monotonically. We propose nonmonotonic reasoning as a competence model of human reasoning. (shrink)

This Element is on new developments in the psychology of reasoning that raise or address philosophical questions. In traditional studies in the psychology of reasoning, the focus was on inference from arbitrary assumptions and not at all from beliefs, and classical binary logic was presupposed as the only standard for human reasoning. But recently a new Bayesian paradigm has emerged in the discipline. This views ordinary human reasoning as mostly inferring probabilistic conclusions from degrees (...) of beliefs, or from hypothetical premises relevant to a purpose at hand, and as often about revising or updating degrees of belief. This Element also covers new formulations of dual-process theories of the mind, stating that there are two types of mental processing, one rapid and intuitive and shared with other animals, and the other slow and reflective and more characteristic of human beings. The final topic covered is the new developments and rationality. (shrink)

In the late summer of 1998, the authors, a cognitive scientist and a logician, started talking about the relevance of modern mathematical logic to the study of human reasoning, and we have been talking ever since. This book is an interim report of that conversation. It argues that results such as those on the Wason selection task, purportedly showing the irrelevance of formal logic to actual human reasoning, have been widely misinterpreted, mainly because the picture of (...) logic current in psychology and cognitive science is completely mistaken. We aim to give the reader a more accurate picture of mathematical logic and, in doing so, hope to show that logic, properly conceived, is still a very helpful tool in cognitive science. The main thrust of the book is therefore constructive. We give a number of examples in which logical theorizing helps in understanding and modeling observed behavior in reasoning tasks, deviations of that behavior in a psychiatric disorder (autism), and even the roots of that behavior in the evolution of the brain. (shrink)

The modus ponens (A -> B, A :. B) is, along with modus tollens and the two logically not valid counterparts denying the antecedent (A -> B, ¬A :. ¬B) and affirming the consequent, the argument form that was most often investigated in the psychology of human reasoning. The present contribution reports the results of three experiments on the probabilistic versions of modus ponens and denying the antecedent. In probability logic these arguments lead to conclusions with imprecise probabilities. (...) In the modus ponens tasks the participants inferred probabilities that agreed much better with the coherent normative values than in the denying the antecedent tasks, a result that mirrors results found with the classical argument versions. For modus ponens a surprisingly high number of lower and upper probabilities agreed perfectly with the conjugacy property (upper probabilities equal one complements of the lower probabilities). When the probabilities of the premises are imprecise the participants do not ignore irrelevant (“silent”) boundary probabilities. The results show that human mental probability logic is close to predictions derived from probability logic for the most elementary argument form, but has considerable difficulties with the more complex forms involving negations. (shrink)

Nonmonotonic reasoning is often claimed to mimic human common sense reasoning. Only a few studies, though, have investigated this claim empirically. We report four experiments which investigate three rules of SYSTEMP, namely the AND, the LEFT LOGICAL EQUIVALENCE, and the OR rule. The actual inferences of the subjects are compared with the coherent normative upper and lower probability bounds derived from a non-infinitesimal probability semantics of SYSTEM P. We found a relatively good agreement of human (...) class='Hi'>reasoning and principles of nonmonotonic reasoning. Contrary to the results reported in the ‘heuristics and biases’ tradition, the subjects committed relatively few upper bound violations (conjunction fallacies). (shrink)

Human Reason and Its Enemies is the result of a two-year research project under a National Fellowship of the Indian Council of Philosophical Research. The book is an uncompromising expose of postmodernism-a philosophy which seeks to destroy philosophy; challenges and objectivity, universality and impartiality of reason; and whcih swears by 'situated' knowledge. The views of many postmoderns, particularly those of Cohen, Foucault, Lyotard, MacIntyre and Taylor, are shown to be superficial, sophistical, confused, fallacious and even ridiculous. Postmodernism believes truth (...) to be culture-relative and therefore believes that intercultural comparison and critical appraisal must require an 'Archimedean point' to make this possible. Since, they say, there is no such point, cultures are incommensurable. This argument, as well as the incommensurability thesis, are shown to be based on messy thinking and prejudice. The postmodern reliance on the concept of 'language games' and its love hate relationship to Western science, are examined in depth. The pronouncements of thinkers like Feyerabend and Kuhn are thoroughly exposed as mistaken and even laughable. An attempt is made to disclose the true nature and salient features of human reason and thinking. A full chapter is devoted to the arch-postmodern, Richard Rorty, and another to feminist writers like Fox Keller, Harding, Irigary and Tiles, who are powerfully drawn to postmodern ideas. (shrink)

Over and above the modalities with which it is expressed in the domains of Kant’s system, the theme of cosmopolitanism embodies the meaning of a philosophy seen as a plan to build on the connection between man, polis and reason; an essential connection that in human reason identifies not a simple endowment which everyone has by nature but a form of life to be realized in the world, a purpose whose binding strength is only fully expressed in the public (...) dimension. (shrink)

Oaksford & Chater (O&C) have rejected logic in favor of probability theory for reasons that are irrelevant to mental-logic theory, because mental-logic theory differs from standard logic in significant ways. Similar to O&C, mental-logic theory rejects the use of the material conditional and deals with the completeness problem by limiting the scope of its procedures to local sets of propositions.

The study of deductive reasoning has been a major paradigm in psychology for approximately the past 40 years. Research has shown that people make many logical errors on such tasks and are strongly influenced by problem content and context. It is argued that this paradigm was developed in a context of logicist thinking that is now outmoded. Few reasoning researchers still believe that logic is an appropriate normative system for most human reasoning, let alone a model (...) for describing the process of human reasoning, and many use the paradigm principally to study pragmatic and probabilistic processes. It is suggested that the methods used for studying reasoning be reviewed, especially the instructional context, which necessarily defines pragmatic influences as biases. (shrink)

This book represents the first major attempt by any author to provide an integrated account of the evidence for bias in human reasoning across a wide range of disparate psychological literatures. The topics discussed involve both deductive and inductive reasoning as well as statistical judgement and inference. In addition, the author proposes a general theoretical approach to the explanations of bias and considers the practical implications for real world decision making. The theoretical stance of the book is (...) based on a distinction between preconscious heuristic processes which determine the mental representation of 'relevant' features of the problem content, and subsequent analytic reasoning processes which generate inferences and judgements. Phenomena discussed and interpreted within this framework include feature matching biases in propositional reasoning, confirmation bias, biasing and debiasing effects of knowledge on reasoning, and biases in statistical judgement normally attributed to 'availability' and 'representativeness' heuristics. In the final chapter, the practical consequences of bias for real life decision making are considered, together with various issues concerning the problem of 'debiasing'. The major approaches discussed are those involving education and training on the one hand, and the development of intelligent software and interactive decision aids on the other. (shrink)

"The central aims of this book are (1) to present an overview of the philosophical debate on trust in the last three decades; (2) to address a central issue in that debate, namely, the presumed prima facie conflict between trust and rationality; and (3) in the course of the analysis, to apply a non-essentialist understanding of psychological concepts, as developed in Wittgenstein's philosophical psychology. The task is not to judge between different definitions of trust. Instead we need awareness of what (...) is implied in a given case when behaviour is singled out as an instance of trust. To invoke the vocabulary of trust and distrust in human interaction is both to describe it, to take a certain perspective on it and to influence it. This is also true in the philosophical debate itself. The issue of trust has been taken up in response to various theoretical conundrums. A dominant theme is the need to refute scepticism and show why trust can be embraced as a rationally justified pursuit. The author argues that this approach must in the end be self-refuting because it would lose the phenomenon it wants to justify. What emerges is instead a conception of rationality that includes the entire web of practices and ways of thinking that constitute human agency, including our ways of speaking about them. We are always already embedded in relations of dependence, we are ethically committed to each other as beings that trust and receive trust"--Bloomsbury Publishing. (shrink)

A recent development in the cognitive science of reasoning has been the emergence of a probabilistic approach to the behaviour observed on ostensibly logical tasks. According to this approach the errors and biases documented on these tasks occur because people import their everyday uncertain reasoning strategies into the laboratory. Consequently participants' apparently irrational behaviour is the result of comparing it with an inappropriate logical standard. In this article, we contrast the probabilistic approach with other approaches to explaining rationality, (...) and then show how it has been applied to three main areas of logical reasoning: conditional inference, Wason's selection task and syllogistic reasoning. (shrink)

The literature has shown that the theory of mental models is able to describe human inductive processes. That theory has been related to the structure of inductive inferences, such as Gautama’s Syllogism indicates. On the other hand, the theory of mental models has also been linked to modal system K. This paper argues that there can be a connection between Gautama’s Syllogism and system K, not in rigorous logical deductions but in describing how the human mind can work. (...) They can refer to two different moments of inductive reasoning; the rule of necessitation of K can be a key element in the second of those moments. (shrink)

The author of the acclaimed Gay Fiction Speaks brings us new interviews with twelve prominent gay writers who have emerged in the last decade. Hear Us Out demonstrates how in recent decades the canon of gay fiction has developed, diversified, and expanded its audience into the mainstream. Readers will recognize names like Michael Cunningham, whose Pulitzer Prize-winning novel The Hours inspired the hit movie; and others like Christopher Bram, Bernard Cooper, Stephen McCauley, and Matthew Stadler. These accounts explore the vicissitudes (...) of writing on gay male themes in fiction over the last thirty years--prejudices of the literary marketplace; social and political questions; the impact of AIDS; commonalities between gay male and lesbian fiction... and even some delectable bits of gossip. (shrink)

According to Aristotle, humans are the rational animal. The borderline between rationality and irrationality is fundamental to many aspects of human life including the law, mental health, and language interpretation. But what is it to be rational? One answer, deeply embedded in the Western intellectual tradition since ancient Greece, is that rationality concerns reasoning according to the rules of logic – the formal theory that specifies the inferential connections that hold with certainty between propositions. Piaget viewed logical (...) class='Hi'>reasoning as defining the end-point of cognitive development; and contemporary psychology of reasoning has focussed on comparing human reasoning against logical standards. (shrink)

It seems that nonmonotonicity of our reasoning is an obvious truth. Almost every logician not even believes, but simply knows very well that a human being thinks in a nonmonotonic way. Moreover, a nonmonotonicity of thinking seems to be a phenomenon parallel to the existence of human beings. Examples allegedly illustrating this phenomenon are not even analyzed today. They are simply quoted. Nowadays, this is a standard approach to nonmonotonicity. However, even simple analysis of those “obvious” examples (...) shows that they illustrate various problems of our thinking, among which none concerns nonmonotonicity. (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)

The Territories of Human Reason is the first major study to explore the emergence of multiple situated rationalities. It focuses on the relation of the natural sciences and Christian theology, but its approach can easily be extended to other disciplines. It provides a robust intellectual framework for discussion of transdisciplinarity, which has become a major theme in many parts of the academic world. McGrath offers a major reappraisal of what it means to be 'rational' which will have significant impact (...) on older discussions of this theme. He sets out to explore the consequences of the seemingly inexorable move away from the notion of a single universal rationality towards a plurality of cultural and domain-specific methodologies and rationalities. This groundbreaking volume will provoke intense discussion and debate. (shrink)

We report the results of three experiments designed to assess the role of suppositions in human reasoning. Theories of reasoning based on formal rules propose that the ability to make suppositions is central to deductive reasoning. Our first experiment compared two types of problem that could be solved by a suppositional strategy. Our results showed no difference in difficulty between problems requiring affirmative or negative suppositions and very low logical solution rates throughout. Further analysis of the (...) error data showed a pattern of responses, which suggested that participants reason from a superficial representation of the premises in these arguments and this drives their choice of conclusion. Our second experiment employed a different set of suppositional problems but with extremely similar proofs in terms of the rules applied and number of inferential steps required. As predicted by our interpretation of reasoning strategies employed in Experiment 1, logical performance was very much higher on these problems. Our third experiment showed that problems that could be solved by constructing an initial representation of the premises were easier than problems in which this representation was not sufficient. This effect was independent of the suppositional structure of the problems. We discuss the implications of this research for theories of reasoning based on mental models and inference rules. (shrink)

The Copernican Revolution had meant for modern Europe surer navigation, bolder voyages and wilder discoveries. With the declaration of independence of America in 1781 and the publication of The Critique of Pure Reason by Immanuel Kant in the same year, the age of Enlightenment defined itself as an age of coming of age and of daring to know. This essay tries to draw out the peculiar enlightenment ethos of a youth against youth through Kant’s depiction of the voyage of (...) class='Hi'>human reason in the First Critique. It will do so by examining the four-fold sense of objects, the island of truth surrounded by illusion, amphibolic insularity, the mirror of schema and the “No Further!” of the Pillars of Hercules. Interrogating the dual sense of “limit” as both infinitizing, transgressively de-territorializing and yet at the same time self-delimiting, self-critiquingly re-territorializing, this essay argues for a hermeneutic vantage point to comprehend Kant as the unwilling mariner who by way of the transcendental as-if attempted to gain a certain spectatorship, a particular possibility of seeing - at a shore already and increasingly lost to the European and global humanity of centuries to come. (shrink)

The work of Tversky, Kahneman and others suggests that people often make use of cognitive heuristics such as availability, salience and representativeness in their reasoning and decision making. Through use of a historical example--the recent plate tectonics revolution in geology--I argue that such heuristics play a crucial role in scientific decision making also. I suggest how these heuristics are to be considered, along with noncognitive factors (such as motivation and social structures) when drawing historical and epistemological conclusions. The normative (...) perspective is community-wide, contextual, and instrumental. (shrink)

Research from ethology and evolutionary biology indicates the following about the evolution of reasoning capacity. First, solving problems of social competition and cooperation have direct impact on survival rates and reproductive success. Second, the social structure that evolved from this pressure is the dominance hierarchy. Third, primates that live in large groups with complex dominance hierarchies also show greater neocortical development, and concomitantly greater cognitive capacity. These facts suggest that the necessity of reasoning effectively about dominance hierarchies left (...) an indelible mark on primate reasoning architectures, including that of humans. In order to survive in a dominance hierarchy, an individual must be capable of (a) making rank discriminations, (b) recognizing what is forbidden and what is permitted based one's rank, and (c) deciding whether to engage in or refriin from activities that will allow one to move up in rank. The first problem is closely tied to the capacity for transitive reasoning, while the second and third are intimately related to the capacity for deontic reasoning. I argue that the human capacity for these types of reasoning have evolutionary roots that reach deeper into our ancestral past than the emergence of the hominid line, and the operation of these evolutionarily primitive reasoning systems can be seen in the development of human reasoning and domain-specific effects in adult reasoning. (shrink)

Paper presented at Cognition, Evolution and Rationality: Cognitive Science for the 21st Century. Oporto, September 2002. To appear in a volume based on that conference edited by Antonio Jose Teiga Zilhao.

This paper attempts to reconcile the claims that the mind is both flat (Chater, 2018) and highly rational (Oaksford & Chater, 2020). According to the flat mind hypothesis, the mind is a mass of inconsistent and contradictory fragments of experience. However, standard accounts of rationality from formal epistemology argue that to be rational, our beliefs must be consistent, and we must believe all the logical consequences of our beliefs. A social account of rationality is developed based on Brandom's (1994) logical (...) expressivism, in which respecting the norms of logic and probability theory is still central but where these standards apply to our public commitments in social dialogical contexts rather than to our individual belief systems (Skovgaard-Olsen, 2017). According to this account, even if someone's individual beliefs are inconsistent, they cannot be condemned as irrational if they acknowledge the inconsistency and seek to resolve it. It is shown how this approach interacts with people's fragmented and shallow world knowledge, and its social distribution yields some counterintuitive consequences, such as it sometimes being rational individually not seeking to resolve contradictions. Other consequences of this social expressivist approach are considered, including for dual process theories of reasoning, our view of beliefs, the status of logic, and Fodor's (1983) view of central systems. It is concluded that people can have flat minds and yet be highly rational. (shrink)

This essay grows out of the conviction that recent work by psychologists studying human reasoning has important implications for a broad range of philosophical issues. To illustrate our thesis we focus on Nelson Goodman's elegant and influential attempt to "dissolve" the problem of induction. In the first section of the paper we sketch Goodman's account of what it is for a rule of inference to be justified. We then marshal empirical evidence indicating that, on Goodman's account of justification, (...) patently invalid inferential rules turn out to be "justified." We conclude that something is seriously wrong with Goodman's story about justification. In the second section we attempt to patch Goodman's account. The notion of epistemic authority and the social aspect of justification play central roles in the alternative account of justification that we propose. (shrink)

In this paper I contemplate two phenomena that have impressed theorists concerned with the domain of reasons and of normativity. One is the much-discussed ‘externality’ of reasons. Reasons are just there, anyway. They exist whether or not agents take any notice of them. They do not only exist in the light of contingent desires or mere inclinations. They are ‘external’ not ‘internal’. They bear on us, even when through ignorance or wickedness we take no notice of them. They thus very (...) conspicuously shine the lights of objectivity, and independence, and even necessity. By basking in this light, ethics is rescued from the slough of sentiment and preference, and regains the dignity denied to it by theorists such as Hobbes or Hume, Gibbard or myself. Many contemporary philosophers compete to stress the external nature of reasons, their shining objectivity.1 The other phenomenon is that of the inescapable ‘normativity’ of means-ends reasoning. Here the irrationality of intending an end but failing to intend the means is a shining beacon of pure practical reason in operation: an indisputable norm, again showing a sublime indifference to whatever weaknesses people actually have, and ideally fitted to provide a Trojan horse for inserting rationality into practical life. If the meansend principle is both practical and the child of rationality itself, then other principles of consistency or of humanity, or of universalizing the maxims of our action, can perhaps follow through the breach in the Humean citadel that it has spearheaded. And so we get the dazzling prospect that if people who choose badly are choosing against reason, then this can be seen to be a special and grave defect. It would locate the kind of fault they are indulging. It would give us, the people of reason, a special lever with which to dislodge their vices. Being able to corral knaves and villains in a compound reserved for those who trespass against reason and rationality may therefore represent definite progress. It is sad to have to spoil the party, but my claim is straightforward.. (shrink)

The 'no-supervenience' theorem (Reason, 2019; Reason and Shah, 2021) is a proof that no fully self-aware system can entirely supervene on any objectively observable system. I here present a simple, non-technical summary of the proof and demonstrate its implications for four separate theories of consciousness: the 'property dualism' theory of David Chalmers; the 'reflexive monism' of Max Velmans; Galen Strawson's 'realistic monism'; and the 'illusionism' of Keith Frankish. It is shown that all are ruled out in their current form by (...) the no-supervenience theorem, except for Chalmers' theory, which I show requires humans to behave irrationally. (shrink)

In comparing humans and animals, we may use humans as the standard to measure animals, or conversely, animals as the standard to measure humans. While most philosophers have adopted the former approach, David Hume is among those few who use the comparison with animals as means to throw light on human nature. I focus on Hume’s treatment of human and animal reason. The cognitive processes and states that Hume holds to be common to humans and animals may be (...) called situated, that is, embedded in the process of guiding actions that is actually going on and consequently relative to the agent’s current position in space-time. Hume’s treatment of causal reasoning underlines the centrality of situated cognition in the workings of human, as well as animal minds. Taking situated reasoning and beliefs as the paradigm of human cognition enables us to look from an alternative point of view, at the features supposedly unique to human cognition, like the use of general words and concepts. Thus we can find a confirmation of the practical import of general words and concepts in Hume’s account of the obligation of promises, where words play an essential role in extending our control over objects and actions beyond what is present and particular into what is absent or not yet actualized. This is also a confirmation of how deeply our cognitive abilities in general are rooted in our practical needs. (shrink)

This paper answers the philosophical contentions defended in Horsten and Welch . It contains a description of the standard format of adaptive logics, analyses the notion of dynamic proof required by those logics, discusses the means to turn such proofs into demonstrations, and argues that, notwithstanding their formal complexity, adaptive logics are important because they explicate an abundance of reasoning forms that occur frequently, both in scientific contexts and in common sense contexts.

Over the last decade, Hugo Mercier and Dan Sperber have elaborated an influential naturalistic account of human reasoning. Their distinctive hypothesis is that its adaptive rationale – and primary function – is to produce and assess reasons in interpersonal justification and argumentation. In this paper I argue, first, that their characterisation of reasoning as based on metarepresentations threatens to oversophisticate reasoning and faces the problem of vicious regress. Second, I argue that they owe us a coherent (...) account of the cognitive role of reasons in reasoning. (shrink)

Are people rational? This question was central to Greek thought and has been at the heart of psychology and philosophy for millennia. This book provides a radical and controversial reappraisal of conventional wisdom in the psychology of reasoning, proposing that the Western conception of the mind as a logical system is flawed at the very outset. It argues that cognition should be understood in terms of probability theory, the calculus of uncertain reasoning, rather than in terms of logic, (...) the calculus of certain reasoning. (shrink)

The biological function of human reasoning abilities cannot be to improve shared knowledge. This is at best a side effect. A more plausible function of argumentation, and thus of reasoning, is to advertise one's ability to detect lies and errors. Such selfish behavior is closer to what we should expect from a naturally selected competence.

This paper answers the philosophical contentions defended in Horsten and Welch (2007, Synthese, 158, 41–60). It contains a description of the standard format of adaptive logics, analyses the notion of dynamic proof required by those logics, discusses the means to turn such proofs into demonstrations, and argues that, notwithstanding their formal complexity, adaptive logics are important because they explicate an abundance of reasoning forms that occur frequently, both in scientific contexts and in common sense contexts.

Those in animal and environmental ethics wishing to extend moral considerability beyond the human community have at some point all had to counter the claim that it is reason that makes human distinct. Detailed arguments against the significance of reason have been rare due to the lack of any good empirical accounts of what reason actually is. Contemporary studies of the embodied mind are now able to fill this gap and show why reason is a poor choice for (...) a criterion to distinguish us from non-human animals. I use studies of the embodied mind to show that rationality is integrally connected to our animal and animate nature and hence not a significant point of departure between human and non-human animals. (shrink)

In my thesis I explain why the common, pre-theoretical understanding of morality is an important part of Kant’s ethics, and I critically evaluate what the strengths and weaknesses are of doing ethics with the common perspective as a point of reference. In chapter 1, I discuss the significance of common rational capacities for the deduction in Groundwork III as well as for the Fact of Reason. Attention to the fundamental role of common rational capacities in the Second Critique reveals that (...) Kant intends to provide further warrant for the Fact than its introspective self-evidence. In chapter 2, I discuss what it means for a rational agent to be endowed with common rational capacities. The agent has everything she needs to reason on her own about what she ought to do and act from rational judgements. Furthermore, I critically evaluate Kant’s claim that his ethics spells out fundamental, pre-theoretical convictions. In chapter 3, I discuss Kant’s conception of rationalizing. I analyse rationalizing as a process of self-deception in which an agent tries to justify or excuse violations of the moral law. This can lead to loss of the reliable use of common rational capacities. I discuss what help critical practical philosophy and moral education can afford against rationalizing. In chapter 4, I argue that Kant saw dialogical engagement with ordinary agents as an important way of obtaining data concerning the correct starting point of practical philosophy. Kant demands that whatever we get from dialog and observation has to be isolated from its contingent elements. I conclude that the main problem for Kant’s method is how we can, on the one hand, exclude non-rational content, and, on the other hand, be open to what other agents actually have to say about morality. (shrink)