Suppose you decide or promise to do something that you have evidence is difficult to do. Should you believe that you will do it? On the one hand, if you believe that you will do it, your belief goes against the evidence—since having evidence that it’s difficult to do it constitutes evidence that it is likely that you won’t do it. On the other hand, if you don’t believe that you will do it but instead believe, as your evidence suggests, (...) that it is likely that you will fail, your decision is not serious and your promise is not sincere. This problem—I call it the Epistemological Problem of Difficult Action—is a pressing philosophical problem that each of us faces. In this paper I consider several possible responses to it. I conclude that the right response is to say that we should believe against the evidence. Cases in which we decide or promise to do something that we have evidence is difficult to do are the best counterexamples to evidentialism. (shrink)

Peter Brössel and Franz Huber in 2015 argued that the Bayesian concept of confirmation had no use. I will argue that it has both the uses they discussed—it can be used for making claims about how worthy of belief various hypotheses are, and it can be used to measure the epistemic value of experiments. Furthermore, it can be useful in explanations. More generally, I will argue that more coarse-grained concepts can be useful, even when we have more fine-grained concepts available.

There is widespread agreement that we cannot know of a lottery ticket we own that it is a loser prior to the drawing of the lottery. At the same time we appear to have knowledge of events that will occur only if our ticket is a loser. Supposing any plausible closure principle for knowledge, the foregoing seems to yield a paradox. Appealing to some broadly Gricean insights, the present paper argues that this paradox is apparent only.

It’s been argued that there are no diachronic norms of epistemic rationality. These arguments come partly in response to certain kinds of counterexamples to Conditionalization, but are mainly motivated by a form of internalism that appears to be in tension with any sort of diachronic coherence requirements. I argue that there are, in fact, fundamentally diachronic norms of rationality. And this is to reject at least a strong version of internalism. But I suggest a replacement for Conditionalization that salvages internalist (...) intuitions, and carves a middle ground between conservatism and evidentialism. (shrink)

Why do we formulate arguments? Usually, things such as persuading opponents, finding consensus, and justifying knowledge are listed as functions of arguments. But arguments can also be used to stimulate reflection on one’s own reasoning. Since this cognitive function of arguments should be important to improve the quality of people’s arguments and reasoning, for learning processes, for coping with “wicked problems,” and for the resolution of conflicts, it deserves to be studied in its own right. This contribution develops first steps (...) towards a theory of reflective argumentation. It provides a definition of reflective argumentation, justifies its importance, delineates it from other cognitive functions of argumentation in a new classification of argument functions, and it discusses how reflection on one’s own reasoning can be stimulated by arguments. (shrink)

Are there any logical norms for argument evaluation besides soundness and inductive strength? The paper will look at several concepts or models introduced over the years, including those of Wisdom, Toulmin, Wellman, Rescher, defeasible reasoning proponents and Walton to consider whether there is common ground among them that supplies an alternative to deductive validity and inductive strength.

Students often study logic on the assumption that it provides a normative guide to reasoning in English. In particular, they are taught to associate connectives like “and” with counterparts in Sentential Logic. English conditionals go over to formulas with → as principal connective. The well-known difficulties that arise from such translation are not emphasized. The result is the conviction that ordinary reasoning is faulty when discordant with the usual representation in standard logic. Psychologists are particularly susceptible to this attitude.

The principle of belief persistence, or conservativity principle, states that ’\Nhen changing beliefs in response to new evidence, you should continue to believe as many of the old beliefs as possible' (Harman, 1986, p. 46). In particular, this means that if an individual gets new information, she has to accommodate it in her new belief set (the set of propositions she believes), and, if the new information is not inconsistent with the old belief set, then (1) the individual has to (...) maintain all the beliefs she previously had and (2) the change should be minimal in the sense that every proposition in the new belief set must be deducible from the union of the old belief set and the new information (see, e.g., Gardenfors, 1988; Stalnaker, 1984). We focus on this minimal notion of belief persistence and characterize it both semantically and syntactically. A ’possible world' semantic formalization of the principle easily comes to mind. The set of all the propositions that the individual believes corresponds to the set of states of the world that she considers possible and is a subset of the set of states that are not ruled out by the individual's information (or knowledge). It is required that, if the individual considers a state possible and her new information does not exclude this state, then she continue to consider it possible. Furthermore, if the individual regards a particular state as impossible, then she should continue to regard it as impossible unless her new information excludes all the states that she previously regarded as possible. This is closely related to the.. (shrink)

Severity of Test (SoT) is an alternative to Popper's logical falsification that solves a number of problems of the logical view. It was presented by Popper himself in 1963. SoT is a less sophisticated probabilistic model of hypothesis testing than Oaksford & Chater's (O&C's) information gain model, but it has a number of striking similarities. Moreover, it captures the intuition of everyday hypothesis testing.

What difference do our decisions make to our reasons for action and the rationality of our actions? There are two questions here, and good grounds for answering them differently. However, it still makes sense to discuss them together. By thinking about the relationships that reasons and rationality bear to decisions, we may be able to cast light on the relationship that reasons and rationality bear to each other.

People have worried for many years — centuries — about how you perform large changes in your body of beliefs. How does the new evidence lead you to replace a geocentric system of planetary motion by a heliocentric system? How do we decide to abandon the principle of the conservation of mass?The general approach that we will try to defend here is that an assumption, presupposition, framework principle, will be rejected or altered when a large enough number of improbabilities must (...) be accepted on be basis of our experience. If I think that all swans are white, and a student claims to have a counterexample, I will assume that he has made some observational error. I will reject his result, and continue to accept the generalization. When a lot of people claim to have seen counterexamples, I will come around: to continue to accept the generalization would require me to accept too many improbabilities. (shrink)

Bermúdez convincingly argues that framing effects are ubiquitous and that this is not a sign of human irrationality, but an unavoidable feature of any intelligent system. The commentary adds that framing effects arise even in formal domains, such as chess and mathematics, which appear paradigms of rational thought. Indeed, finding and attempting to resolve clashes between different frames is a major impetus for deliberative cognition.

Some authors have called into question the normativity of logic, using as an argument that the bridge principles for logical normativity (MacFarlane, In what sense (in any) is logic normative for thought, 2004 )? are just by-products of general epistemic principles for belief. In this paper, I discuss that suggestion from a formal point of view. I show that some important bridge principles can be derived from usual norms for belief. I also describe some possible ways to block this derivation (...) by modifying the epistemic norms or weakening the bridge principles. Finally, I discuss different philosophical interpretations of these results. (shrink)

In the human cognitive economy there are four grades of epistemic involvement. Knowledge partitions into distinct sorts, each in turn subject to gradations. This gives a fourwise partition on ignorance, which exhibits somewhat different coinstantiation possibilities. The elements of these partitions interact with one another in complex and sometimes cognitively fruitful ways. The first grade of knowledge I call “anselmian” to echo the famous declaration credo ut intelligam, that is, “I believe in order that I may come to know”. As (...) construed here, one knows in this anselmian way that E = mc2 just in case one knows that sentence expresses a true statement, but without having to understand the proposition it expresses. Most epistemologists ignore the significance of this grade of epistemic involvement. In a second grade of epistemic involvement, knowing that E = mc2 is knowing what that sentence means and understanding the proposition it express. This is knowledge in the propositional or semantic sense, and is the dominant target of epistemological investigation. Tacit and implicit knowledge occupies another tier. A typical example would be something that someone has “known all along” but, until now, hasn’t had occasion to put her mind to it or formulate in words. TI-knowledge remains a minority interest in today’s epistemology. Operating at a fourth grade of epistemic involvement is what I call “impact”-knowledge, which is the knowledge of a matter at its deepest and most widespread. An example, to be discussed below, is the knowledge that was generated by the Wiles proof of Fermat’s last theorem. Its true importance lies not only, or even mainly, in its verification of a commonly accepted fact about numbers, but rather in its enrichment of the mathematics of elliptical curves and the promise it holds for greater advancement into the mathematical unknown. Knowledge of this fourth grade has yet to find a seat in the parliaments of epistemology. Knowledge of the anselmian sort is independent of the other three. Tacit and implicit knowledge is incompatible with anselmian and semantic knowledge but coinstantiable with impact-knowledge. Semantic knowledge is incompatible with tacit and implicit knowledge but coinstantiable with the others. Impact-knowledge is pairwise coinstantiable with the others. Below I will bring the ignorance partitions into such alignment as they have with these ones. In doing so, I’ll propose a naturalized causal response epistemology designed to give these interactive distinctions the theoretical air they need to breathe. (shrink)

I argue in favor of a certain connection between knowledge and the permissibility of action. On this approach, we do not think of the relation between those notions as reflecting a universal epistemic principle. Instead, we think of it as something resembling a platitude from folk psychology. With the help of some elementary tools from the logic of normativity and counterfactuals, I attempt to establish the connection by deriving it from more elementary principles. The new formulation involves a ceteris paribus (...) clause. Though it is often difficult to specify the exact content of a ceteris paribus clause, we will see that our clause is derived from a descriptive generalization with independent motivation. (shrink)

According to a popular closure principle for epistemic justification, if one is justified in believing each of the premises in set Φ and one comes to believe that ψ on the basis of competently deducing ψ from Φ—while retaining justified beliefs in the premises—then one is justified in believing that ψ. This principle is prima facie compelling; it seems to capture the sense in which competent deduction is an epistemically secure means to extend belief. However, even the single-premise version of (...) this closure principle is in conflict with certain seemingly good inferences involving the epistemic possibility modal ♢. According to other compelling principles concerning competent deduction and epistemic justification, one can competently infer ¬♢φ from ¬φ in deliberation even though there are cases in which one can justifiably believe ¬φ but would be unjustified in believing ¬♢φ. Thus, as we argue, philosophers must choose between unrestricted closure for justification and the validity of these other principles. (shrink)

This paper continues a recent exchange in this journal concerning explanationist accounts of epistemic justification. In the first paper in this exchange, Byerly argues that explanationist views judge that certain beliefs about the future are unjustified when in fact they are justified. In the second paper, McCain defends a version of explanationism which he argues escapes Byerly’s criticism. Here we contribute to this exchange in two ways. In the first section, we argue that McCain’s defense of explanationism against Byerly’s objection (...) is unsuccessful. Then, in the second section, we develop an independent objection to explanationism from a different direction. If our arguments in each section are sound, then not only do explanationist accounts of epistemic justification judge beliefs that are justified to be unjustified, but they judge beliefs that are unjustified to be justified. Explanationism faces problems on both sides. (shrink)

Many have the intuition that the right response to the Lottery Paradox is to deny that one can justifiably believe of even a single lottery ticket that it will lose. The paper shows that from any theory of justification that solves the paradox in accordance with this intuition, a theory not of that kind can be derived that also solves the paradox but is more conducive to our epistemic goal than the former. It is argued that currently there is no (...) valid reason not to give preference to the derived accounts over the accounts from which they come. (shrink)

The underconsideration argument against inference to the best explanation and scientific realism holds that scientists are not warranted in inferring that the best theory is true, because scientists only ever conceive of a small handful of theories at one time, and as a result, they may not have considered a true theory. However, antirealists have not developed a detailed alternative account of why explanatory inference nevertheless appears so central to scientific practice. In this paper, I provide new defences against some (...) recent objections to the underconsideration argument, while also developing an account of explanatory inference that both survives these criticisms and does not entail realism. (shrink)

Within the field of virtue and vice epistemology open-mindedness is usually considered an archetypal virtue. Nevertheless, there is ongoing disagreement over how exactly it should be defined. In this paper I propose a novel definition of open-mindedness as a process of impartial belief revision and use it to argue that we should shift our normative assessments away from the trait itself to the context in which it is exercised. My definition works by three sequential stages: not screening new claims, impartially (...) weighing the evidential strength of claims, and updating beliefs accordingly. Using this definition I argue for a focus on agents’ particular circumstances to determine what degrees of credulity, open-, or closed-mindedness are appropriate in any given situation. As well as providing conceptual clarity regarding the concept of open-mindedness this paper indicates the benefits of this contextual approach for our everyday epistemic attitudes. In particular it enables us to recognise, without stigma, when ourselves or others deviate from open-mindedness for appropriate reasons. (shrink)

The international community has not been able to agree on a definition of “terrorism,” which has been a controversial term for decades. In order to understand the controversy, here the meaning of “terrorism” is analysed by means of the inferentialist framework developed by Robert Brandom. It will be shown that there is wide agreement about (at least some of) the consequences of application of the term, whereas the conditions of application are precisely what is at issue. Three consequences of application (...) will be distinguished: epistemic, evaluative, and programmatic. Evaluative and programmatic consequences of application of the term “terrorism” are widespread and very serious, even in the absence of a precise definition, and that explains why the conditions of application are a controversial matter. In the end, the controversy is best understood as a clash of interests regarding when the consequences of the term should apply. (shrink)

It is argued that higher-order awareness is central to one type of everyday rationality. The author starts by specifying the target notion of rationality, contrasting it with other useful notions in the neighbourhood. It is then shown that the target notion relies on first-person awareness of the unfolding of cognition. This is used to explain the kernel of truth in epistemic conservatism, the structure of defeasibility, and the root motive behind the widely accepted distinction between rational inference and trivial entailment.

ABSTRACT: I shall consider the phenomenon of believing ourselves to have at least one false belief: a phenomenon I call believed fallibility I shall first present a paradoxical argument which appears to show that believed fallibility is incoherent; second, note that this argument assumes that we are committed to the conjunction of all our beliefs; third, sketch a more intuitive notion of commitment in which we are not committed to the conjunction of all our beliefs and argue that the original (...) paradoxical argument is now defused; fourth, construct a new paradoxical argument showing that if we believe that we have at least one false belief we are committed to a contradiction, employing the preferable notion of commitment; and, fifth, suggest that perhaps we might avoid the new paradox by denying that closing our beliefs under conjunction is required by rationalityRÉSUMÉ: Je me pencherai ici sur le phénomène qui consiste à penser que nous avons au moins une opinion fausse: je nomme ce phénoméne «la croyance d’etre faillible». Je présente en premier lieu un argument paradoxal qui semble démontrer que la croyance d’être faillible est incohérente. Deuxièmement, je remarque que cet argument suppose que nous nous obligions à réaliser la conjonction de toutes nosopinions. Troisièmement, je propose une version plus intuitive de cette obligation selon laquelle nous ne sommes pas obligés de réaliser la conjonction de toutes nos opinions, et je soutiens que le paradoxe initial est alors désamorcé. Quatrièmement, je construis un nouvel argument paradoxal démontrant que, si nous croyons que nous avons au moins une opinion fausse, nous sommes obligés de nous contredire, selon la notion d’obligation que je préconise d’adopter. Cinquièmement, je suggère que nous pourrions peut-être éviter ce nouveau paradoxe en niant que la rationalité exige de soumettre nos opinions à la conjonction. (shrink)

Marianna Bergamaschi Ganapini argues that we can believe the error theory. In this reply, I explain why I still think we cannot.

The paper argues that argument and argumentation deserve philosophical attention but do not receive it, and proposes some explanations. It then asks whether there is a field of philosophy, “philosophy of argument,” that might attract philosophers’ attention. A case is made that such a field exists. However, challenges to that case seriously undermine it. Thus those who want philosophers to pay more attention to argument must find other ways to make their case.

This paper provides a computational characterization of coherence that applies to a wide range of philosophical problems and psychological phenomena. Maximizing coherence is a matter of maximizing satisfaction of a set of positive and negative constraints. After comparing five algorithms for maximizing coherence, we show how our characterization of coherence overcomes traditional philosophical objections about circularity and truth.

Je suis trés reconnaissant à Michel Seymour d'avoir soumis mon livre à un examen détaillé, pénétrant, et charitable et d'avoir, par ses objections, mis le doigt sur un certain nombre de présupposés des thèses défendues dans ce livre, qu'il a souvent articulés bien mieux que je n'ai été capable de le faire. Le principal de ces présupposés est mon rejet implicite de la thése quinienne de l'indétermination de la traduction, qui m'engage, selon Seymour, à défendre une conception conservatrice de la (...) logique et à insister sur une détermination de son domaine qui lui paraît injustifiée. Seymour soutient au contraire qu'il faut admettre cette thése, qui «commande une tout autre perspective» que la mienne. Je voudrais à la fois résister à la prémisse et à la conclusion de cette inférence. (shrink)

Traditional epistemologists assumed that the most important doxastic norms were rational requirements on belief. This orthodoxy has recently been challenged by the work of revolutionary epistemologists on the rational requirements on credences. Revolutionary epistemology takes it that such contemporary work is important precisely because traditional epistemologists are mistaken—credal norms are more fundamental than, and determinative of, belief norms. To make sense of their innovative project, many revolutionary epistemologists have also adopted another commitment, that norms on credences are governed by a (...) fundamental accuracy norm. Unfortunately for the revolutionary epistemologist, it has been difficult to define a measure of accuracy while maintaining that credal norms are more basic than belief norms. In this paper, I criticize one such proposal for measuring accuracy, that the accuracy of our credences should be assessed in terms of what we know, arguing that this picture ultimately cannot vindicate the revolutionary approach. (shrink)

One can intend the actions of others, even when one believes such actions are not under one’s control. Call the objects of intentions “ends”; the ends that consist of other people’s actions “social”; and the ends that consist of things one believes one cannot control “recalcitrant”. The thesis, then, is that one can intend recalcitrant social ends. I present a positive argument in favor of this idea, and then argue against some purported conditions on the possible content of intentions that (...) would rule out the possibility of intending such ends. The positive argument is the following: intentions are realized by a certain cluster of dispositions. One can come to be so disposed towards recalcitrant social ends. So one can come to be disposed toward such ends in the manner that realizes an intention. So one can intend recalcitrant social ends. The conditions against which I argue are known in the literature as the Own Action Condition, the Control Condition, and the Settle Condition. I present cases where, intuitively, agents genuinely intend ends that would be ruled out by these conditions. (shrink)

Jason Stanley’s Knowledge and Practical Interests is a brilliant book, combining insights about knowledge with a careful examination of how recent views in epistemology fit with the best of recent linguistic semantics. Although I am largely convinced by Stanley’s objections to epistemic contextualism, I will try in what follows to formulate a version that might have some prospect of escaping his powerful critique.

It has been argued by several writers that practical reasoning is capable of a kind of validity that is unlike the validity which theoretical reasoning can possess. One can gain an initial impression of this view's appeal, as well as of its content, by seeing how it could issue from analytical reflection upon the idea that actions, decisions and intentions all can be, and frequently are, reasonable . An inviting first step in such reflection is to say that for a (...) certain intention, say, to be reasonable on a certain occasion is, roughly, for it to be true that a person could come to have that intention as a result of reasoning well about what to do. One might then add the further thought that, so far as regards what it is for a piece of reasoning to be well done, reasoning falls into at least two basic kinds: reasoning about what to do differs generically from reasoning about what is the case. The view which I mentioned at the outset can now be seen as a specific proposal regarding where this difference lies: reasoning about what to do has distinctive validity-conditions not shared by reasoning about what is the case. (shrink)

Of all the problems attending the sense-datum theory, arguably the deepest is that it draws a veil of appearances over the external world. Today, the sense-datum theory is widely regarded as an overreaction to the problem of hallucination. Instead of accounting for hallucination in terms of intentional relations to sense data, it is often thought that we should account for it in terms of intentional relations to properties. In this paper, however, I argue that in the versions that might address (...) the problem of hallucination, this newer account is guilty of a vice similar to sense-datum theory’s: it draws a veil of abtracta over the concrete world. (shrink)

In this paper, I examine an account of instrumental reasoning recently put forth by John Broome. His key suggestion is that anyone who engages in reasoning about his intentions also believes that he will do what he intends to do and that combined with a belief about necessary means this creates rational pressure towards believing that one will take the necessary means. I argue that Broome’s model has three significant problems; his key premise is false—the sincere expression of an intention (...) does not entail the belief that one will successfully execute that intention; his account yields a model of instrumental reasoning that is uncomfortably reflective; he seems unable to explain the rational pressure towards taking necessary means that arises directly from having an end and an instrumental belief. All three problems, I argue, are a consequence of Broome’s inadequate position on what it is to intend to do something. (shrink)

The AGM paradigm for belief revision provides a very elegant and powerful framework for reasoning about idealized agents. The paradigm assumes that the modeled agent is a perfect reasoner with infinite memory. In this paper we propose a framework to reason about non-ideal agents that generalizes the AGM paradigm. We first introduce a structure to represent an agent's belief states that distinguishes different status of beliefs according to whether or not they are explicitly represented, whether they are currently active and (...) whether they are fully accepted or provisional. Then we define a set of basic operations that change the status of beliefs and show how these operations can be used to model agents with different capacities. We also show how different operations of belief change described in the literature can be seen as special cases of our theory. (shrink)

Let me begin by sincerely thanking the commentators for taking the time to share their insightful reactions to the target article [Callender 2022a]. I am very fortunate to have so many talented, di...

The project of naturalizing ethics has multiple contributions, from cognitive and moral psychology to primatology, neuroscience or evolutionary theory. One of the strategies for naturalizing ethics has been to argue that moral norms and values can be explained away if we focus on their causal history, if it is possible to offer both an ultimate and proximate causal explanation for them. In this article, I will focus on the contribution of cognitive and moral psychology as a way of offering a (...) proximate causal explanation for moral judgments. I am mostly interested in understanding to what extent these cognitive and psychological questions have some bearing in the fields of ethics and meta-ethics. Does this research programme put at stake the contention that ethics is a manifestation of human rationality? Is it true that finding the cognitive underpinnings of some of our moral judgments vindicates some meta-ethical position, namely some kind of reductionist naturalism? In the end, I will argue that even if scientific disciplines such as cognitive psychology give us a naturalized picture of the moral agent, there seem to be no reasons to think that from a naturalized perspective of the agent capable of perceiving value it must follow the naturalization of value itself. (shrink)

There are several features of law which rightly draw the interest of philosophers, especially those whose expertise lies in ethics and social and political philosophy. But the law also has features which haven’t stirred much in the way of philosophical investigation. I must say that I find this surprising. For the fact is that a well-run criminal trial is a master-class in logic and epistemology. Below I examine the logical and epistemological properties of greatest operational involvement in a criminal proceedings, (...) concepts such as evidence, proof, argument, inference, relevance, probability, and more. My principal objective is to expose the deep cleavage between establishment norms in epistemology and logic and standard practice in criminal proceedings. This gives us two options to reflect upon. In one, the establishment norms for the correct management of the concepts in question are basically sound. In that case, as I will show, common law criminal practice would be basically unsound; its convictions would be basically false and unjust. Seen from the other perspective, the criminal justice system would be basically sound, and its criminal convictions basically true and just. It turns out to matter that option one meets with widely spread common disbelief and is generally taken as contrary to common knowledge. What is needed here is an epistemology which gives these sentiments some air to breathe. I will argue that on balance it is the logico-epistemic establishment which requires some serious rethinking. (shrink)

This essay criticizes Joseph Raz’s service conception of authority on the basis of its knowability condition. The condition states that for agents to be justified in following authoritative directives, they must be able to know (i.e., form reliable beliefs) that the authority issuing the directives is in fact legitimate. Three grounds for concern are identified. The first is that the satisfaction of the normal justification thesis (NJT), which states that the legitimacy of authorities hinges on whether their directives enable subjects (...) to better conform to reason, only provides agents with reasons to believe that it is justified to act as if an authority were legitimate (i.e., on the assumption that it is). Based on the belief/acceptance distinction, the NJT allows for a gap between what is actually the case and what agents are willing to go along with in order to improve the likelihood of conforming to right reason. The independence condition (IC), which states that for those matters where the NJT obtains it must be better for a subject to improve such conformity than to decide for herself, must be satisfied in conjunction with the NJT, but suffers from its own particular problems. Thus, the second problem identified is that of incommensurable values, which appears when agents are not able to decide between the value of improving right reason—NJT—and the value of deciding for themselves—IC. Finally, the third problem is that of vagueness about right reason, where agents attempting to determine whether an authority meets the two conditions are not able to settle whether reason is improved. Together, these three problem areas of knowability serve to challenge Raz’s position. (shrink)

This thesis studies the role of conceptual content in inference and reasoning. The first two chapters offer a theoretical and historical overview of the relation between inference and meaning in philosophy and psychology. In particular, a critical analysis of the formality thesis, i.e., the idea that rational inference is a rule-based and topic-neutral mechanism, is advanced. The origins of this idea in logic and its influence in philosophy and cognitive psychology are discussed. Chapter 3 consists of an analysis of the (...) relationship between inference and representation. It is argued that inference has to be studied from a pluralistic per- spective due to its dependence on different formats of representing information. The following four chapters apply conceptual spaces, a formal theory of concepts within cognitive semantics, to three concept-based inference-types. First, an explication of Sellars notion of material inference is advanced. Later, the model is extended to account for nonmonotonic inference by studying the role expectations in reasoning. Finally, a conceptual space-model of category-based induction is presented. This model predicts most of the empirical properties of this psychological phenomenon and subsumes some of the previous theories in psychology. It is stated that the explanatory fruitfulness of this new approach is evidence for the failure of the formality thesis and calls for a unified model of rational inference that puts semantics at center stage. The last chapter of the thesis discusses how inference and concepts interact in scientific reasoning, which makes constant use of hybrid symbolic structures for representing conceptual information. Stephen Toulmin’s notions of method of representation and inferential technique are developed and applied in a case study about the emergence of the notion of instantaneous speed during the passage from geometrical physics to analytical mechanics. It is claimed that this analysis provides support to the pluralistic perspective for theorizing about reasoning. (shrink)