In a 2002 article Stewart Cohen advances the “bootstrapping problem” for what he calls “basic justification theories,” and in a 2010 followup he offers a solution to the problem, exploiting the idea that suppositional reasoning may be used with defeasible as well as with deductive inference rules. To curtail the form of bootstrapping permitted by basic justification theories, Cohen insists that subjects must know their perceptual faculties are reliable before perception can give them knowledge. But how is such (...) knowledge of reliability to be acquired if not through perception itself? Cohen proposes that such knowledge may be acquired a priori through suppositional reasoning. I argue that his strategy runs afoul of a plausible view about how epistemic principles function; in brief, I argue that one must actually satisfy the antecedent of an epistemic principle, not merely suppose that one does, to acquire any justification by its means – even justification for a merely conditional proposition. (shrink)

James Van Cleve raises some objections to my attempt to solve the bootstrapping problem for what I call “basic justification theories.” I argue that given 1 the inference rules endorsed by basic justification theorists, we are a priori (propositionally) justified in believing that perception is reliable. This blocks the bootstrapping result.

To suppose X means to pretend to change one's belief for the sake of the argument to include X. How to do so is a decision problem: of the many ways to modify one's beliefs to include X, one should choose the one that best fits with one's epistemic goals. I examine the role of suppositional reasoning in the evaluation of purported scientific explanations of various sorts, based on Hempel and Oppenheim's deductive-nomological and inductive-statistical explanations. First, I present (...) for each type of explanation the suppositional reasoning conditions it must satisfy. For example, the dipping of blue litmus paper in acid explains why it turned red only if, when one supposes that the litmus paper was not dipped in acid, one must also give up the belief that it turned red. Second, I argue that a specific decision making method should be used to determine how one is to change one's beliefs for the sake of the argument in each case. Third, I evaluate in detail whether purported explanations, both intuitively explanatory and intuitively non-explanatory satisfy these conditions. Fourth, I show that the suppositional reasoning conditions for explanations, when evaluated correctly, systematically solve the many counterexamples to the original Hempel-Oppenheim model. (shrink)

Suppositional reasoning can seem spooky. Suppositional reasoners allegedly (e.g.) “extract knowledge from the sheer workings of their own minds” (Rosa), even where the knowledge is synthetic a posteriori. Can literary fiction pull such a rabbit out of its hat? Where P is a work’s fictional ‘premise’, some hold that some works reason declaratively (supposing P, Q), imperatively (supposing P, do Q), or interrogatively (supposing P, Q?), and that this can be a source of knowledge if the (...) class='Hi'>reasoning is good. True, I will argue, although only within the context of judicious critical interpretation. Further evident constraints include that the form of the suppositional reasoning needs to be declarative or imperative, and that the fictional ‘premise’ of the work needs to be a metaphysical counterfactual possibility, not merely a temporal counterfactual and not merely an epistemic possibility or probabilistic supposition. (shrink)

The aim of this paper is to investigate two related aspects of human reasoning, and use the results to construct an automated theorem prover for the predicate calculus that at least approximately models human reasoning. The result is a non-resolution theorem prover that does not use Skolemization. It involves two central ideas. One is the interest constraints that are of central importance in guiding human reasoning. The other is the notion of suppositional reasoning, wherein one (...) makes a supposition, draws inferences that depend upon that supposition, and then infers a conclusion that does not depend upon it. Suppositional reasoning is involved in the use of conditionals and reductio ad absurdum, and is central to human reasoning with quantifiers. The resulting theorem prover turns out to be surprisingly efficient, beating most resolution theorem provers on some hard problems. (shrink)

An application of the Method of Analysis of Relational Complexity (MARC) to suppositional reasoning in the knight-knave task is outlined. The task requires testing suppositions derived from statements made by individuals who either always tell the truth or always lie. Relational complexity (RC) is defined as the number of unique entities that need to be processed in parallel to arrive at a solution. A selection of five ternary and five quaternary items were presented to 53 psychology students using (...) a pencil and paper format. A computer-administered version was presented to 50 students. As predicted, quaternary problems were associated with higher error rates and longer response times than ternary problems. The computer-administered form was more difficult than the pencil and paper version of the test. These differences are discussed in terms of RC theory and alternative processing accounts. Together, they indicate that the relational complexity metric is a useful and parsimonious way to quantify complexity of reasoning tasks. (shrink)

Deductive reasoning shares with other forms of thinking a reliance on strategies, as shown by the results of three experiments on the nature and development of control strategies to solve suppositional deductions. These puzzles are based on assertors who may or may not be telling the truth, and their assertions about their status as truthtellers and liars. The first experiment shows that reasoners make backward inferences as well as forward inferences, to short-cut their way through the alternatives, and (...) the generation of suppositions is a source of difficulty. The second experiment establishes that the elimination of the suppositional status of an individual does not render problems easier. The third experiment shows that reasoners can improve their reasoning accuracy and speed spontaneously, without feedback, and it clarifies the transfer of strategies and their development. We discuss the implications of these data for alternative theories of suppositional deduction and for the relationship between reasoning and other forms of thinking such as problem solving. (shrink)

Two experiments investigated inferences based on suppositions. In Experiment 1, the subjects decided whether suppositions about individuals' veracity were consistent with their assertions—for example, whether the supposition “Ann is telling the truth and Beth is telling a lie”, is consistent with the premises: “Ann asserts: I am telling the truth and Beth is telling the truth. Beth asserts: Ann is telling the truth”. It showed that these inferences are more difficult than ones based on factual premises: “Ann asserts: I live (...) in Dublin and Beth lives in Dublin”. There was no difference between problems about truthtellers and liars, who always told the truth or always lied, and normals, who sometimes told the truth and sometimes lied. In Experiment 2, the subjects made inferences about factual matters set in three contexts: a truth-inducing context in which friends confided their personality characteristics, a lie-inducing context in which business rivals advertised their products, and a neutral context in which computers printed their program characteristics. Given the supposition that the individuals were lying, it was more difficult to make inferences in a truth-inducing context than in the other two contexts. We discuss the implications of our results for everyday reasoning from suppositions, and for theories of reasoning based on models or inference rules. (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)

Case-based reasoning is a familiar method of evaluating sentences. But when applied to conditionals, it seems to lead to implausible conclusions. In this paper I argue that the problem arises from equating the probability of a conditional sentence on the evidential supposition of some condition with the conditional probability of the former, given the latter.

In ‘Reasoning and Regress’ I argued that inferring a conclusion from a set of propositions may simply consist in taking it that the conclusion follows from these propositions—thereby defusing familiar regress arguments. Sinan Dogramaci challenges the generality of this view, on the grounds that sometimes you may draw conclusions from no premisses that you believe. I respond by clarifying a distinction between the premisses of an argument from the reasons your conclusion is based upon. While suppositional reasoning (...) may involve no premisses in the former sense, it does not follow that it does not involve concluding something on the basis of reasons. This allows the view defended in ‘Reasoning and Regress’ to extend to suppositional reasoning. (shrink)

Rodden writes, “How do stories persuade us? How do they ‘move’—and move us? The short answer: by analogies.” Rodden’s claim is a natural first view, also held by others. This chapter considers the extent to which this view is true and helpful in understanding how fictional narratives, taken as wholes, may be argumentative, comparing it to the two principal (though not necessarily exclusive) alternatives that have been proposed: understanding fictional narratives as exhibiting the structure of suppositional argument, or the (...) structure of a kind of transcendental argument. Three key aspects of understanding a fictional narrative as an argument from analogy are identified. First, the argument will be relativistic or depend in an essential way upon the circumstances or intentions of the auditor or author. Second, in view of the first aspect, the argument will be loose and subjective, and accordingly less likely to yield knowledge. Third, the argument will not exhibit a distinctive structure applicable only to fictional narratives. I find that the third, and sometimes the first and second, of these same three aspects apply to understanding fictional narratives as suppositional arguments. I present considerations that point to a way of establishing that some extended fictions exhibit the structure of a kind of transcendental argument that is neither relativistic nor subjective, is knowledge-generating, and is uniquely applicable to fictional narratives. This supports literary cognitivism—the thesis that “literary fiction can be a source of knowledge in a way that depends crucially on its being fictional.”. (shrink)

I object to Markos Valaris’s thesis that reasoning requires a belief that your conclusion follows from your premisses. My counter-examples highlight the important but neglected role of suppositional reasoning in the basis of so much of what we know.

Arguments and conditionals are powerful means language provides us to reason about possibilities and to reach conclusions from premises. These two kinds of constructions exhibit several affinities—e.g., they both come in different varieties depending on the mood; they share some of the same connectives (i.e., ‘then’); they allow for similar patterns of modal subordination. In the light of these affinities, it is not surprising that prominent theories of conditionals—old and new suppositionalisms as well as dynamic theories of conditionals—as well as (...) certain reductive theories of arguments tend to semantically assimilate conditionals and arguments. In this paper, I shall marshall some linguistic evidence as well as some theoretical considerations for thinking that, despite these similarities, arguments and conditionals should be given a different semantics and I shall lay out a framework that can capture at least some of their affinities while accounting for their outstanding differences. (shrink)

This paper presents a unifying diagnosis of a number of important problems facing existing models of rational choice under moral uncertainty and proposes a remedy. I argue that the problems of (i) severely limited scope, (ii) intertheoretic comparisons, and (iii) 'swamping’ all stem from the way in which values are assigned to options in decision rules such as Maximisation of Expected Choiceworthiness. By assigning values to options under a given moral theory by asking something like ‘how much do I desire (...) this option, supposing this theory is true?’ rather than ‘how much value does this theory assign to this option?’ these problems can be avoided, while the appealing features of these accounts can be preserved. This amendment provides a role for the preferences, desires, or goals of rational agents that is curiously absent from the existing discussion of what individuals rationally ought to do when they are uncertain about what they morally ought to do. (shrink)

A popular view maintains that supposition is a kind of cognitive mental state, very similar to belief in essential respects. Call this view “cognitivism about supposition”. There are at least three grades of cognitivism, construing supposition as (i) a belief, (ii) belief-like imagination or (iii) a species of belief-like imagination. I shall argue against all three grades of cognitivism and claim that supposition is a sui generis form of imagination essentially dissimilar to belief. Since for good reasons (i) is not (...) supported in the literature, I shall dwell on (ii) and (iii). Without further explanation supposition has been very often merely postulated as being nothing but belief-like imagination—that is, (ii). I shall show that at least two considerations undermine (ii). First, supposition and belief-like imagination are governed by different norms, more precisely the former is freer than the latter and requires minimal or no mental effort. Second, contrary to belief-like imagination, supposition is “cold”, in that it is typically dissociated from emotional reactions. Proponents of (iii) face the pressure of explaining these differences between supposition and belief-like imagination too. I shall argue that they have not sufficiently motivated the claim that supposition is belief-like. In particular they fail to accommodate precisely the dimensions of supposition pertaining to its normativity and emotionality. I shall close with a sketch of a new account of supposition. (shrink)

This dissertation is devoted to empirically contrasting the Suppositional Theory of conditionals, which holds that indicative conditionals serve the purpose of engaging in hypothetical thought, and Inferentialism, which holds that indicative conditionals express reason relations. Throughout a series of experiments, probabilistic and truth-conditional variants of Inferentialism are investigated using new stimulus materials, which manipulate previously overlooked relevance conditions. These studies are some of the first published studies to directly investigate the central claims of Inferentialism empirically. In contrast, the (...) class='Hi'>Suppositional Theory of conditionals has an impressive track record through more than a decade of intensive testing. The evidence for the Suppositional Theory encompasses three sources. Firstly, direct investigations of the probability of indicative conditionals, which substantiate “the Equation” (P(if A, then C) = P(C|A)). Secondly, the pattern of results known as “the defective truth table” effect, which corroborates the de Finetti truth table. And thirdly, indirect evidence from the uncertain and-to-if inference task. Through four studies each of these sources of evidence are scrutinized anew under the application of novel stimulus materials that factorially combine all permutations of prior and relevance levels of two conjoined sentences. The results indicate that the Equation only holds under positive relevance (P(C|A) – P(C|¬A) > 0) for indicative conditionals. In the case of irrelevance (P(C|A) – P(C|¬A) = 0), or negative relevance (P(C|A) – P(C|¬A) < 0), the strong relationship between P(if A, then C) and P(C|A) is disrupted. This finding suggests that participants tend to view natural language conditionals as defective under irrelevance and negative relevance (Chapter 2). Furthermore, most of the participants turn out only to be probabilistically coherent above chance levels for the uncertain and-to-if inference in the positive relevance condition, when applying the Equation (Chapter 3). Finally, the results on the truth table task indicate that the de Finetti truth table is at most descriptive for about a third of the participants (Chapter 4). Conversely, strong evidence for a probabilistic implementation of Inferentialism could be obtained from assessments of P(if A, then C) across relevance levels (Chapter 2) and the participants’ performance on the uncertain-and-to-if inference task (Chapter 3). Yet the results from the truth table task suggest that these findings could not be extended to truth-conditional Inferentialism (Chapter 4). On the contrary, strong dissociations could be found between the presence of an effect of the reason relation reading on the probability and acceptability evaluations of indicative conditionals (and connate sentences), and the lack of an effect of the reason relation reading on the truth evaluation of the same sentences. A bird’s eye view on these surprising results is taken in the final chapter and it is discussed which perspectives these results open up for future research. (shrink)

In Constructing the World, Chalmers observes that our knowledge exceeds the core evidence provided by our senses and introspection. Thus, on the basis of core evidence, one also can know (S) that water covers the majority of the Earth. This knowledge, Chalmers suggests, requires a great deal of apriori knowledge. Chalmers argues that even if one suspends belief in one’s core evidence, one can nevertheless reason from a description of this evidence to an ordinary claim such as S. Chalmers concludes (...) that the ordinary claim must be apriori entailed by a description of the core evidence. However, I propose that careful thinking about belief suspension reveals that empirical information can contaminate the reasoning from the core evidence to the ordinary claim S, even if belief in the core evidence is suspended. One result is that empiricists and externalists may freely appeal to thought experiments without having to concede that there are substantive apriori truths. (shrink)

Applying good inductive rules inside the scope of suppositions leads to implausible results. I argue it is a mistake to think that inductive rules of inference behave anything like 'inference rules' in natural deduction systems. And this implies that it isn't always true that good arguments can be run 'off-line' to gain a priori knowledge of conditional conclusions.

I first support Alec Fisher's thesis that premises and conclusions in arguments can be unasserted first by arguing in its favor that only it preserves our intuition that it is at least possible that two arguments share the same premises and the same conclusion although not everything that is asserted in the one is also asserted in the other and second by answering two objections that might be raised against it. I then draw from Professor Fisher's thesis the consequence that (...) in suppositional arguments the falsity (or unacceptability) of a supposition does not tell unfavorably in the evaluation of the argument, because the falsity (or unacceptability) of a (nonredundant) premise counts against an argument if and only if that premise is asserted. Finally, I observe that, despite the fact that they are neither expressed nor even alluded to, implicit assumptions in arguments are always asserted, unless the conclusion, but none of the explicit premisses, is unasserted. Hence, apart from an exceptional case of the kind just mentioned, the falsity (or unacceptability) of implicit assumptions always counts against an argument. (shrink)

Philotheus boehner's "medieval logic" gives the impression that medieval supposition theory and modern quantification theory agree on their interpretation of particular propositions but differ on their interpretation of universal propositions. Matthews shows that this impression is mistaken: they differ on both particular and universal propositions, And the basic reason is that the medievals quantify over terms while modern logicians quantify over variables. (staff).

[Marilyn McCord Adams] In this paper I begin with Aristotle's Categories and with his apparent forwarding of primary substances as metaphysically special because somehow fundamental. I then consider how medieval reflection on Aristotelian change led medieval Aristotelians to analyses of primary substances that called into question how and whether they are metaphysically special. Next, I turn to a parallel issue about supposits, which Boethius seems in effect to identify with primary substances, and how theological cases-the doctrines of the Trinity, the (...) Incarnation, and of the human soul's separate survival between death and resurrection-call into question how and to what extent supposits are metaphysically special. I conclude with some reflections on various senses of being metaphysically special and how they pertain to primary substances and supposits. /// [Richard Cross] Scotus's belief that any created substance can depend on the divine essence and/or divine persons as a subject requires him to abandon the plausible Aristotelian principle that there is no merely relational change. I argue that Scotus's various counterexamples to the principle can be rebutted. For reasons related to those that arise in Scotus's failed attempt to refute the principle, the principle also entails that properties cannot be universals. (shrink)

Williamson has argued against scepticism concerning our metaphysically modal knowledge, by arguing that standard patterns of suppositional reasoning to counterfactual conclusions provide reliable sources of correct ascriptions of possibility and necessity. The paper argues that, while Williamson’s claims relating to necessity may well be right, he has not provided adequate reasons for thinking that the familiar modes of counterfactual reasoning to which he points generalise to provide a decent route to ascriptions of possibility. The paper also explores (...) another path to ascriptions of possibility that may be extracted from Williamson’s ideas, before briefly considering the general status of counterfactual reasoning in relation to our knowledge of possibilities. (shrink)

This paper has two main parts. In the first part, we motivate a kind of indeterminate, suppositional credences by discussing the prospect for a subjective interpretation of a causal Bayesian network, an important tool for causal reasoning in artificial intelligence. A CBN consists of a causal graph and a collection of interventional probabilities. The subjective interpretation in question would take the causal graph in a CBN to represent the causal structure that is believed by an agent, and interventional (...) probabilities in a CBN to represent suppositional credences. We review a difficulty noted in the literature with such an interpretation, and suggest that a natural way to address the challenge is to go for a generalization of CBN that allows indeterminate credences. In the second part, we develop a decision-theoretic foundation for such indeterminate suppositional credences, by generalizing a theory of coherent choice functions to accommodate some form of act-state dependence. The upshot is a decision-theoretic framework that is not only rich enough to, so to speak, ground the probabilities in a subjectively interpreted causal network, but also interesting in its own right, in that it accommodates both act-state dependence and imprecise probabilities. (shrink)

In this paper I deal with epistemological issues that stem from the hypothesis that reasoning is not only a means of transmitting knowledge from premise-beliefs to conclusion-beliefs, but also a primary source of knowledge in its own right. The idea is that one can gain new knowledge on the basis of suppositional reasoning. After making some preliminary distinctions, I argue that there are no good reasons to think that purported examples of knowledge grounded on pure reasoning (...) are just examples of premise-based inferences in disguise. Next, I establish what kinds of true propositions can to a first approximation be known on the basis of pure reasoning. Finally, I argue that beliefs that are competently formed on the basis of suppositional reasoning satisfy both externalist and internalist criteria of justification. (shrink)

It seems natural to think that there are aesthetic reasons for action and that an artist must be guided by such reasons as he or she begins work on the canvas or poem or symphony or marble. This latter supposition seems at odds, however, not only with classical inspiration theory but also with the views of one of the last century’s most important philosophers of art, R. G. Collingwood. We propose an account of acting for an aesthetic reason inspired by (...) G. E. M. Anscombe’s Intention, specifically by her concept of ‘practical knowledge’, which we believe can accommodate Collingwood’s reservations about the sort of knowledge of their ends, and of the means to those ends, which artists have as they engage in their creative activity. (shrink)

In “On the Nature of Logical Judgment” (published 1893) and A New Law of Thought and Its Logical Bearings (published 1911), E. E. Constance Jones developed a view on which we can think and talk about the round-square. On her view, the round-square has a kind of existence; otherwise, sentences about it wouldn’t be meaningful. But it doesn’t exist in space, since it’s both round and square, and nothing in space is both. Although it has a kind of existence in (...) what she calls “a Region of Supposition,” we can truly say that it “doesn’t exist,” if what we mean is that it doesn’t exist in space. It plays a role in reasoning, since we need to be able to reason about it to conclude that it doesn’t exist in space. And, although the round-square is both round and square, the Law of Contradiction needn’t be violated, provided that it’s understood in light of Jones’s distinction between two kinds of negation. (shrink)

[Marilyn McCord Adams] In this paper I begin with Aristotle's Categories and with his apparent forwarding of primary substances as metaphysically special because somehow fundamental. I then consider how medieval reflection on Aristotelian change led medieval Aristotelians to analyses of primary substances that called into question how and whether they are metaphysically special. Next, I turn to a parallel issue about supposits, which Boethius seems in effect to identify with primary substances, and how theological cases-the doctrines of the Trinity, the (...) Incarnation, and of the human soul's separate survival between death and resurrection-call into question how and to what extent supposits are metaphysically special. I conclude with some reflections on various senses of being metaphysically special and how they pertain to primary substances and supposits. /// [ Richard Cross] Scotus's belief that any created substance can depend on the divine essence and/or divine persons as a subject requires him to abandon the plausible Aristotelian principle that there is no merely relational change. I argue that Scotus's various counterexamples to the principle can be rebutted. For reasons related to those that arise in Scotus's failed attempt to refute the principle, the principle also entails that properties cannot be universals. (shrink)

This paper examines the "causal theory of reference", according to which science aims at the discovery of "essences" which are the objects of reference of natural kind terms (among others). This theory has been advanced as an alternative to traditional views of "meaning", on which a number of philosophical accounts of science have relied, and which have been criticized earlier by the present author. However, this newer theory of reference is shown to be equally subject to fatal internal difficulties, and (...) to be incompatible with actual science as well. Indeed, it rests on assumptions which it shares with the purportedly opposing theory of meaning. Behind those common assumptions is the supposition that the nature of science can be illuminated by an examination of alleged necessities of language which are independent of the results and methods of scientific inquiry. An alternative view of science is proposed, according to which the goals and language of science develop as integral parts of the process of demarcating science from non-science, a process in which the notion of a "reason" gradually assumes a decisive role. On this view, the comparability, competition, and development of scientific ideas are understood without reliance on either common "meanings" or common "references" as fundamental tools of analysis. (shrink)

This book by one of the world's foremost philosophers in the fields of epistemology and logic offers an account of suppositional reasoning relevant to practical deliberation, explanation, prediction and hypothesis testing. Suppositions made 'for the sake of argument' sometimes conflict with our beliefs, and when they do, some beliefs are rejected and others retained. Thanks to such belief contravention, adding content to a supposition can undermine conclusions reached without it. Subversion can also arise because suppositional reasoning (...) is ampliative. These two types of nonmonotonic logic are the focus of this book. A detailed comparison of nonmonotonicity appropriate to both belief contravening and ampliative suppositional reasoning reveals important differences that have been overlooked. (shrink)

Our understanding of folk and scientific psychology often informs the law’s conclusions regarding questions about the voluntariness of a defendant’s action. The field of psychology plays a direct role in the law’s conclusions about a defendant’s guilt, innocence, and term of incarceration. However, physical sciences such as neuroscience increasingly deny the intuitions behind psychology. This paper examines contemporary biases against the autonomy of psychology and responds with considerations that cast doubt upon the legitimacy of those biases. The upshot is that (...) if reasonable doubt is established regarding whether psychology’s role in the law should be displaced, then there is room for future work to be done with respect to the truth of psychology’s conclusions about criminal responsibility. (shrink)

Action explanations like ‘I am heading to the ferry because the bridge is closed,’ are supposed to require restatement: ‘I am... because I believe the bridge is closed,’ because (i) the objective claim may be false though the intended explanation is correct, and (ii) because objective circumstances have to be cognitively mediated if they are to bear on action. This supposition is rejected here. Restatements cannot withdraw the objective claim without withdrawing the explanation. In the context of reason‐giving, belief statements (...) do not function as assertions about the inner life. The fact that belief statements may be true though the belief itself is false creates the illusion of distinctive subject matters. The illusion is exploited by conceptions of belief positing stored representations. Even if there were such representations, retrieved for the sake of expressing previously acquired beliefs, the expression of belief must endorse p and cannot merely advert to the existence and content of a representation. The reverse of the standard philosophical view about restatement is actually correct. Wherever an agent correctly adduces a belief that an objective circumstance obtains in explaining his action, a de‐psychologizing restatement that merely makes the objective claim must be ascribable to the agent. (shrink)

The traditional view in epistemology has it that knowledge is insensitive to the practical stakes. More recently, some philosophers have argued that knowledge is sufficient for rational action: if you know p, then p is a reason you have (epistemically speaking). Many epistemologists contend that these two claims stand in tension with one another. In support of this, they ask us to start with a low stakes case where, intuitively, a subject knows that p and appropriately acts on p. Then, (...) they ask us to consider a high stakes version of the case where, intuitively, this subject does not know that p and could not appropriately act on p without double-checking. Finally, they suggest that the best explanation for our shifty intuitions is that p is a reason the subject has in the low stakes case but not in the high stakes case. In short, according to this explanation, having a reason (in the epistemic sense) is sensitive to the stakes. If so, either knowledge is sensitive to the stakes or else you can know that p even if p is not a reason you have (in the epistemic sense). In this paper, I consider more closely the relation between having a reason (in the epistemic sense) and having a reason to check. I argue that the supposition that if one has p as a reason (in the epistemic sense) then one has a reason not to check whether p, or no reason to check whether p, is highly doubtful. On the contrary, I suggest, it is plausible that, given our fallibility, one always has an epistemic reason to check whether p, whether or not p is a reason one has (in the epistemic sense). On the basis of this observation, I show that one can offer a new way of explaining the cases in question, allowing us to reconcile the traditional view about knowledge and the sufficiency of knowledge for rational action. (shrink)

Moral theorists often say such things as “But surely A ought to do such and such,” or “Plainly it is morally permissible for B to do so and so,” and do not even try to prove that those judgments are true. Moreover, they often rest weight on the supposition that those judgments are true. In particular, they often rest theories on them: they take them as data. Others object. They say that nobody is entitled to rest any weight at all (...) on judgments such as those. They say, not that the judgments are false, but that there is no reason to believe them true. They say, more generally, that there is no reason to think of any moral judgment that it is true. I will call this The No Reason Thesis. Is there reason to think The No Reason Thesis true? There are lots of arguments for it in the literature, but I want to focus on one of them in particular. I think that the one I will focus on lies behind all the others, but no matter if it does not: I suggest that if this argument fails, they all fail. (shrink)

An organizing theme of the dissertation is the issue of how to make philosophical theories useful for scientific purposes. An argument for the contention is presented that it doesn’t suffice merely to theoretically motivate one’s theories, and make them compatible with existing data, but that philosophers having this aim should ideally contribute to identifying unique and hard to vary predictions of their theories. This methodological recommendation is applied to the ranking-theoretic approach to conditionals, which emphasizes the epistemic relevance and the (...) expression of reason relations as part of the semantics of the natural language conditional. As a first step, this approach is theoretically motivated in a comparative discussion of other alternatives in psychology of reasoning, like the suppositional theory of conditionals, and novel approaches to the problems of compositionality and accounting for the objective purport of indicative conditionals are presented. In a second step, a formal model is formulated, which allows us to derive quantitative predictions from the ranking-theoretic approach, and it is investigated which novel avenues of empirical research that this model opens up for. Finally, a treatment is given of the problem of logical omniscience as it concerns the issue of whether ranking theory (and other similar approaches) makes too idealized assumptions about rationality to allow for interesting applications in psychology of reasoning. Building on the work of Robert Brandom, a novel solution to this problem is presented, which both opens up for new perspectives in psychology of reasoning and appears to be capable of satisfying a range of constraints on bridge principles between logic and norms of reasoning, which would otherwise stand in a tension. (shrink)

People frequently report that their thought has, at times, a vocal character. Thinking commonly appears to be accompanied or constituted by silently ‘talking’ to oneself in inner speech. In this paper, I argue that inner speech ‘utterances’ can constitute occurrent propositional attitudes, e.g., occurrent judgments, suppositions, etc., and, thereby, we can consciously reason through tokening a series of inner speech utterances in working memory. As I demonstrate, the functional role a mental state plays in working memory is determined in a (...) flexible and context sensitive manner by metacognitive monitoring and control procedures. An inner speech utterance functions as an occurrent judgment (and, thus, as a premise, lemma, or conclusion in a line of conscious reasoning) when it is experienced with a level of certainty that exceeds one’s threshold of confidence for acceptance. In virtue of an agent experiencing an inner speech utterance with a sufficient level of certainty, the utterance plays the functional role of an occurrent judgment through, e.g., terminating inquiry and causing overt actions (like overtly asserting the words rehearsed in inner speech). (shrink)

Counterfactual reasoning has been used to account for many aspects of scientific reasoning. More recently, it has also been used to account for the scientific practice of modeling. Truth in a model is truth in a situation considered as counterfactual. When we reason with models, we reason with counterfactuals. Focusing on selected models like Bohr’s atom model or models of population dynamics, I present an account of how the imaginative development of a counterfactual supposition leads us from reality (...) to interesting model assumptions; how it guides our reasoning from these assumptions to interesting consequences for the model scenario via counterfactual entailment; and how it leads us back to conclusions on real target phenomena. (shrink)

A general two-stage theory of human inference is proposed. A distinction is drawn between heuristic processes which select items of task information as ‘relevant’, and analytic processes which operate on the selected items to generate inferences or judgements. These two stages are illustrated in a selective review of work on both deductive and statistical reasoning. Factors identified as contributing to heuristic selection include perceptual salience, linguistic suppositions and semantic associations. Analytic processes are considered to be context dependent: people reason (...) from experience, not from inference rules. The paper includes discussion of the theory in comparison with other contemporary theories of human inference, and in relation to the current debate about human rationality. (shrink)

Taxonomy Based modeling was applied to describe drivers' mental models of variable message signs (VMS's) displayed on expressways. Progress in road telematics has made it possible to introduce variable message signs (VMS's). Sensors embedded in the carriageway every 500m record certain variables (speed, flow rate, etc.) that are transformed in real time into 'driving times' to a given destination if road conditions do not change. VMS systems are auto-regulative Man-Machine (AMMI) systems which incorporate a model of the user: if the (...) traffic flow is too high, then drivers should choose alternative routes. In so doing, the traffic flow should decrease. The model of the user is based on suppositions such as: people do not like to waste time, they fully understand the displayed messages, they trust the displayed values, they know of alternative routes. However, people also have a model of the way the system functions. And if they do not believe the contents of the message, they will not act as expected. We collected data through interviews with drivers using the critical incidents technique (Flanagan, 1985). Results show that the mental models that drivers have of the way the VMS system works are various but not numerous and that most of them differ from the 'ideal expert' mental model. It is clear that users don't have an adequate model of how the VMS system works and that VMS planners have a model of user behaviour that does not correspond to the behaviour of the drivers we interviewed. Finally, Taxonomy Based Modeling is discussed as a tool for mental model remediation. (shrink)

Taxonomy Based modeling was applied to describe drivers’ mental models of variable message signs (VMS’s) displayed on expressways. Progress in road telematics has made it possible to introduce variable message signs (VMS’s). Sensors embedded in the carriageway every 500m record certain variables (speed, flow rate, etc.) that are transformed in real time into “driving times” to a given destination if road conditions do not change.VMS systems are auto-regulative Man-Machine (AMMI) systems which incorporate a model of the user: if the traffic (...) flow is too high, then drivers should choose alternative routes. In so doing, the traffic flow should decrease. The model of the user is based on suppositions such as: people do not like to waste time, they fully understand the displayed messages, they trust the displayed values, they know of alternative routes. However, people also have a model of the way the system functions. And if they do not believe the contents of the message, they will not act as expected.We collected data through interviews with drivers using the critical incidents technique (Flanagan, 1985). Results show that the mental models that drivers have of the way the VMS system works are various but not numerous and that most of them differ from the“ideal expert” mental model. It is clear that users don’t have an adequate model of how the VMS system works and that VMS planners have a model of user behaviour that does not correspond to the behaviour of the drivers we interviewed. Finally, Taxonomy Based Modeling is discussed as a tool for mental model remediation. (shrink)

I address three issues in this paper: first, just as many have thought that there is a requirement of alternative possibilities for the truth of judgments of moral responsibility, is there reason to think that the truth of judgments of intrinsic value also presupposes our having alternatives? Second, if there is this sort of requirement for the truth of judgments of intrinsic value, is there an analogous requirement for the truth of judgments of moral obligation on the supposition that obligation (...) supervenes on goodness? Third, if the truth of judgments of intrinsic value and those of moral obligation do presuppose our having access to alternatives, what should be said about whether determinism imperils the truth of such judgments? I defend an affirmative answer to the first question, a more guarded answer to the second, and a yet more restrained answer to the third. (shrink)

ABSTRACT This part of the series has a dual purpose. In the first place we will discuss two kinds of theories of proof. The first kind will be called a theory of linear proof. The second has been called a theory of suppositional proof. The term "natural deduction" has often and correctly been used to refer to the second kind of theory, but I shall not do so here because many of the theories so-called are not of the second (...) kind--they must be thought of either as disguised linear theories or theories of a third kind (see postscript below). The second purpose of this part is 25 to develop some of the main ideas needed in constructing a comprehensive theory of proof. The reason for choosing the linear and suppositional theories for this purpose is because the linear theory includes only rules of a very simple nature, and the suppositional theory can be seen as the result of making the linear theory more comprehensive. CORRECTION: At the time these articles were written the word ‘proof’ especially in the phrase ‘proof from hypotheses’ was widely used to refer to what were earlier and are now called deductions. I ask your forgiveness. I have forgiven Church and Henkin who misled me. (shrink)

Relatively little is known about those who consistently produce the valid response to Modus Tollens (MT) problems. In two studies, people who responded correctly to MT problems indicated how “convinced” they were by proofs of conditional reasoning conclusions. The first experiment showed that MT competent reasoners found accurate proofs of MT reasoning more convincing than similar “proofs” of invalid reasoning. Similarly, there was a tendency for MT competent reasoners to find an initial counterfactual supposition more convincing than (...) did people who were less competent in MT. The second experiment showed that when individuals produced the correct MT response, and found correct MT proofs to be more convincing than “bogus” proofs, they were also less likely to find the conclusions to Denying the Antecedent, or Affirming the Consequent problems valid, compared to individuals who could not discriminate between valid and bogus MT proofs. These findings are discussed in terms of both their implications for the mental logic and mental models positions, and individual differences in System 1 and System 2 reasoning. (shrink)

Aristotle notoriously excludes free women and both male and female artisans and slaves from citizenship in the polis on the basis of an identifiable difference in nature: all of these groups, unlike free males, possess and exhibit some delinquency in their capacity for reason. Commentators have typically interpreted Aristotle’s comments on the nature of free women by suggesting that free women by nature have heightened or increased propensities towards incontinent behavior. If this is indeed the only difference between the natures (...) of free men and free women, then it remains difficult to see why the appropriate modes of education in addition to the practice of habit would fail to ameliorate this deficiency in free women. My intention is to argue that Aristotle does think of the difference in the capacity for reason between free men and free women as a difference of kind—namely, women lack the capacity to develop practical reason—and as a result, justifiably, at least within the suppositions of his own position, excludes free women from citizenship. (shrink)

Taxonomy Based modeling was applied to describe drivers’ mental models of variable message signs (VMS’s) displayed on expressways. Progress in road telematics has made it possible to introduce variable message signs (VMS’s). Sensors embedded in the carriageway every 500m record certain variables (speed, flow rate, etc.) that are transformed in real time into “driving times” to a given destination if road conditions do not change. VMS systems are auto-regulative Man-Machine (AMMI) systems which incorporate a model of the user: if the (...) traffic flow is too high, then drivers should choose alternative routes. In so doing, the traffic flow should decrease. The model of the user is based on suppositions such as: people do not like to waste time, they fully understand the displayed messages, they trust the displayed values, they know of alternative routes. However, people also have a model of the way the system functions. And if they do not believe the contents of the message, they will not act as expected. (shrink)