Data involving epistemic modals suggest that some classically valid argument forms, such as _reductio_, are invalid in natural language reasoning as they lead to modal collapses. We adduce further data showing that the classical argument forms governing the existential quantifier are similarly defective, as they lead to a _de re–de dicto_ collapse. We observe a similar problem for disjunction. But if the classical argument forms for negation, disjunction and existential quantification are invalid, what are the correct forms that govern (...) the use of these items? Our diagnosis is that epistemic modals interfere with hypothetical reasoning. We present a modal first-order logic and model theory that characterizes hypothetical reasoning with epistemic modals in a principled manner. One upshot is a sound and complete natural deduction system for reasoning with epistemic modals in first-order logic. (shrink)

In his important monograph, Hypothetical Reasoning, Nicholas Rescher develops a modal theory in order to throw some light on the nature of hypothetical reasoning and on the so-called "problem of counterfactual conditionals." I should like both to expound the theory and consider its application.

Introduction Kant develops a positive though regulative role for reason toward the end of the Dialectic of the Critique of Pure Reason, particularly in the Appendix to the Dialectic. In the opening section, “The Regulative Employment of the Ideas of Pure Reason”, he provides us with an account of how these ideas can unify the understanding in its employment, although only regulatively. Part of this account includes a discussion of the hypothetical use of reason, in which one inspects a (...) group of particulars to see whether they fit a given universal and then generalizes over other future particulars that the universal will apply to them as well. (shrink)

This is the first book-length study published of the structure of reasoning and argument dependent on hypotheses. It encompasses far more than the, by now, familiar discussion of contrafactual conditional—this is but one chapter—since it ranges over such topics as the nature of hypothetical inference, belief-contravening hypotheses, contrafactual conditionals and modality, and entailment of conclusion from premisses under restriction. There are three appendices which concern, respectively, the historical roots of hypothetical reasoning and its attendant perplexities, the (...) difficulty concerned in the mutual compatibility of hypotheses in a proof, and certain properties of laws of nature expressed in conditional form. There is a fair-sized bibliography listing all the more important works on hypothetical reasoning. Rescher's logical apparatus designed to facilitate hypothetical reasoning and its study is controversial; but anyone wishing to understand the logic of the problems set forth in current philosophical discussion must begin with Rescher's book.—P. J. M. (shrink)

In his celebrated article on the contrary-to-fact conditional Roderick Chisholm makes the following astute observation.

This paper studies the use of hypothetical and value-based reasoning in US Supreme-Court cases concerning the United States Fourth Amendment. Drawing upon formal AI & Law models of legal argument a semi-formal reconstruction is given of parts of the Carney case, which has been studied previously in AI & law research on case-based reasoning. As part of the reconstruction, a semi-formal proposal is made for extending the formal AI & Law models with forms of metalevel reasoning (...) in several argument schemes. The result is compared with Rissland’s (1989) analysis in terms of dimensions and Ashley’s (2008) analysis in terms of his process model of legal argument with hypotheticals. (shrink)

Most error theorists want to accept hypothetical reasons but not moral reasons. They do so by arguing that there is no queerness in hypothetical reasons. They can be reduced to purely descriptive claims, about either standards or ordinary standard-independent facts: when I say “I have a reason to take this flight, ” all I say is that “according to certain standards of reasoning, I have a reason to take this flight” or that “I have a desire such (...) that taking this flight is the only way of doing so.” Error theorists who want to accept hypothetical reasons but not moral reasons think that one of these approaches works for hypothetical reasons but neither work for moral reasons. I shall argue that whatever arguments are given for rejecting these approaches in the case of moral reasons are also arguments for rejecting them in the case of hypothetical reasons. (shrink)

Theoretical and manipulative abduction conjectures and manipulations : the extra-theoretical dimension of scientific discovery. -- Non-explanatory and instrumental abduction : plausibility, implausibility, ignorance preservation. -- Semiotic brains and artificial minds : how brains make up material cognitive systems. -- Neuromultimodal abduction : pre-wired brains, embidiment, neurospaces. -- Animal abduction : from mindless organisms to srtifactual mediators. -- Abduction, affordances, and cognitive niches : sharing representations and creating chances through cognitive niche construction. -- Abduction in human and logical agents : hasty (...) generalizers, hybrid abducers, fallacies. -- Morphodynamical abduction : causation of hypotheses by attractors dynamics. (shrink)

This is an excerpt from the contentMost academics have heard of deduction and induction, but much less familiar is the kind of inference that the American philosopher Charles Peirce called abduction. Abductive inference is the generation and evaluation of explanatory hypotheses, a kind of reasoning that is far more common and important than deductions, which rarely occur outside of mathematics, and inductions from examples to generalizations. Lorenzo Magnani has produced a magnum opus on abduction that brilliantly spans its philosophical, (...) neuropsychological, computational, and ecological dimensions. In this review I will briefly highlight some of the substantial contributions of Abductive Cognition and raise a few objections to it. I finish by briefly discussing the relevance of abduction to concerns about mind and society. Magnani’s treatise is by far the most comprehensive discussion of abductive thinking to date. In the first chapter, he reviews various ways of thinking about abduction, ranging from sentential approac. (shrink)

Altruism is a well-established reason underlying research participation. Less is known about altruism in adolescent-parent decision-making about clinical trials enrolling healthy adolescents. This qualitative investigation focused on identifying spontaneous statements of altruism within adolescent-parent (dyadic) discussions of participation in a hypothetical phase I clinical trial related to adolescent sexual health. Content analysis revealed several response patterns to each other’s altruistic reasoning. Across 70 adolescent-parent dyads in which adolescents were 14 to 17 years of age and 91% of their (...) parents were mothers, a majority (61%) of dyadic discussions included a statement reflecting altruism. Parents responded to adolescents’ statements of altruism more frequently than adolescents responded to parents’ statements. Responses included: expresses concern, reiterates altruistic reasoning, agrees with altruistic reasoning, and adds to/expands altruistic reasoning. Since an altruistic perspective was often balanced with concerns about risk or study procedures, researchers cannot assume that altruism will directly lead to study participation. Optimizing the informed consent process for early phase clinical trials involving healthy adolescents may include supporting parents to have conversations with their adolescents which will enhance their capacity to consider all aspects of trial participation. (shrink)

Lorenzo Magnani: Abductive Cognition: The Epistemological and Eco-Cognitive Dimensions of Hypothetical Reasoning Content Type Journal Article Category Book Review Pages 1-7 DOI 10.1007/s11023-011-9267-6 Authors Cameron Shelley, Centre for Society, Technology, and Values, University of Waterloo, Waterloo, Canada Journal Minds and Machines Online ISSN 1572-8641 Print ISSN 0924-6495.

Peirce presented early formulations of abductive inference nearly 150 years ago. Since then new interpretations have been presented (some of them quite independently of Peirce), but there is still a close link to Peirce’s formulations. Lorenzo Magnani has written a new book on abduction where the main theme is not Peirce’s interpretation of abduction as such, but the book is very interesting from the Peircean perspective. In this review I shall focus on some of the themes from this point of (...) view. Magnani presents a broad view on abduction instead of presenting only one specific interpretation of abduction. This reflects the history of abduction. Peirce’s writings themselves give elements for various.. (shrink)

Ernst Mach’s defense of relativist theories of motion in Die Mechanik involves a well-known criticism of Newton’s theory appealing to absolute space, and of Newton’s “bucket” experiment. Sympathetic readers (Norton 1995) and critics (Stein 1967, 1977) agree that there’s a tension in Mach’s view: he allows for some constructed scientific concepts, but not others, and some kinds of reasoning about unobserved phenomena, but not others. Following Banks (2003), I argue that this tension can be interpreted as a constructive one, (...) springing from Mach’s approach to scientific reasoning. Mach’s “economy of science” allows for a principled distinction to be made, between natural and artificial hypothetical reasoning, and Mach defends a division of labor between the sciences in a 1903 paper for The Monist, “Space and Geometry from the Point of View of Physical Inquiry”. That division supports counterfactual reasoning in Mach’s system, something that’s long been denied is possible for him. (shrink)

There is evidence that bidders fall prey to the winner’s curse because they fail to extract information from hypothetical events—like winning an auction. This paper investigates experimentally whether bidders in a common value auction perform better when the requirements for this cognitive issue—also denoted by contingent reasoning—are relaxed, leaving all other parameters unchanged. For my underlying research question, I used a lab experiment with two stages. In stage I, the subjects participate in a non-standard common value auction, called (...) the wallet game, in which a naïve bidding strategy can lead to both winner’s curse and loser’s curse. In stage II, the subjects in the treatment group learn whether their initial bid was the winning bid or not and they get the opportunity to change this bid. In this sense, the bidders face the same decision problems as in stage I again, but the need for hypothetical thinking is reduced in stage II. The overall pattern of the data suggests that the problem of irrational over- and underbidding can be weakened by giving the subjects ex ante feedback about their bid, but unlike related studies I also find negative effects of additional information. (shrink)

The research described here explores the idea of using Supreme Court oral arguments as pedagogical examples in first year classes to help students learn the role of hypothetical reasoning in law. The article presents examples of patterns of reasoning with hypotheticals in appellate legal argument and in the legal classroom and a process model of hypothetical reasoning that relates them to work in cognitive science and Artificial Intelligence. The process model describes the relationships between an (...) advocate’s proposed test for deciding a case or issue, the facts of the hypothetical and of the case to be decided, and the often conflicting legal principles and policies underlying the issue. The process model of hypothetical reasoning has been partially implemented in a computerized teaching environment, LARGO (“Legal ARgument Graph Observer”) that helps students identify, analyze, and reflect on episodes of hypothetical reasoning in oral argument transcripts. Using LARGO, students reconstruct examples of hypothetical reasoning in the oral arguments by representing them in simple diagrams that focus students on the proposed test, the hypothetical challenge to the test, and the responses to the challenge. The program analyzes the diagrams and provides feedback to help students complete the diagrams and reflect on the significance of the hypothetical reasoning in the argument. The article reports the results of experiments evaluating instruction of first year law students at the University of Pittsburgh using the LARGO program as applied to Supreme Court personal jurisdiction cases. The learning results so far have been mixed. Instruction with LARGO has been shown to help law student volunteers with lower LSAT scores learn skills and knowledge regarding hypothetical reasoning better than a text-based approach, but not when the students were required to participate. On the other hand, the diagrams students produce with LARGO have been shown to have some diagnostic value, distinguishing among law students on the basis of LSAT scores, posttest performance, and years in law school. This lends support to the underlying model of hypothetical argument and suggests using LARGO as a pedagogically diagnostic tool. (shrink)

This volume explores the conceptual terrain defined by the Greek word eikos: the probable, likely, or reasonable. A term of art in Greek rhetoric, a defining feature of literary fiction, a seminal mode of historical, scientific, and philosophical inquiry, eikos was a way of thinking about the probable and improbable, the factual and counterfactual, the hypothetical and the real. These thirteen original and provocative essays examine the plausible arguments of courtroom speakers and the 'likely stories' of philosophers, verisimilitude in (...) art and literature, the likelihood of resemblance in human reproduction, the limits of human knowledge and the possibilities of ethical and political agency. The first synthetic study of probabilistic thinking in ancient Greece, the volume illuminates a fascinating chapter in the history of Western thought. (shrink)

Hypothetical consent is puzzling. On the one hand, it seems to make a moral difference across a wide range of cases. On the other hand, there seem to be principled reasons to think that it cannot. In this article I put forward reasonably precise formulations of these general suspicions regarding hypothetical consent; I draw several distinctions regarding the ways in which hypothetical consent may make a moral difference; I distinguish between two autonomy-related concerns, nonalienation and sovereignty; and, (...) utilizing these distinctions, I show that—and in a preliminary way, when—the objections to the moral significance of hypothetical consent fail. (shrink)

A hypothetical reasoning, which can find an explanation for a given set of observation by assuming some hypothetical sets, is a useful knowledge processing framework because of its theoretical basis and usefulness for practical problems such as diagnostics, scheduling, and design. It is, however, known to be computationally very expensive for large problems because it must deal with incomplete knowledge. Predicate-logic allows powerful and compact knowledge representation compared to propositional-logic. Efficient methods to proceed reasoning have been (...) developed for propositional-logic. However it would be desirable to develop similar methods for predicate-logic, but this has so far proved difficult. “KICK-HOPE” is one of hypothetical reasoning systems for predicate-logic. KICK-HOPE, which is based on a deductive database technique called the QSQR method and a basic fast hypothetical reasoning system called ATMS, made advances in the speed of reasoning. However, for a practical knowledge base, ‘the inconsistent process’ and ‘the subsumption process’ still consume much calculation time. In this paper, we investigate an e.cient method of the inconsistent and subsumption processes of KICK-HOPE. First, we show most of these processes are vain and omissible. Second, to omit vain processes, we introduce bit-vector to represent what hypotheses include in hypothetical sets. And, we improve that vain processes will be reduced to check the check-vector. Finally, we examine the proposed system with two examples, a diagnostic problem of a logic circuit and a scheduling problem. It is shown to be more efficient than the original KICK-HOPE for all problems. (shrink)

We often assume that hypothetical approval – either in the form of preferences or consent – under ideal conditions adds to the legitimacy of an arrangement or act. I want to show that this assumption, reasonable as it may seem, will also give rise to ethical problems. I focus on three problem areas: prudence, euthanasia and coercive psychiatric treatment. If we are to count as prudentially or morally␣relevant those preferences you would have if you were informed and rational, we (...) will run into difficulties in all these areas if your actual and rational preferences are at variance with each other. In the prudential sphere we may question the personal value of satisfying preferences that a person does not actually have. In this case our problem concerns the point of satisfying a rational preference in conflict with an actual one. In the cases of euthanasia and coercive care it concerns instead whether it would be morally right to do such a thing. I doubt there is a simple solution to our problem. In this paper at most I prepare the way for a solution or for wiser decisions in the hard cases, by pointing out what they will have to deal with. (shrink)

The logic of proofs is a refinement of modal logic introduced by Artemov in 1995 in which the modality ◻A is revisited as ⟦t⟧A where t is an expression that bears witness to the validity of A. It enjoys arithmetical soundness and completeness and is capable of reflecting its own proofs . We develop the Hypothetical Logic of Proofs, a reformulation of LP based on judgemental reasoning.

The so-called Substituted Judgment Standard is one of several competing principles on how certain health care decisions ought to be made for patients who are not themselves capable of making decisions of the relevant kind. It says that a surrogate decision-maker, acting on behalf of the patient, ought to make the decision the patient would have made, had the latter been competent. The most common way of justifying the Substituted Judgment Standard is to maintain that this standard protects patients’ right (...) to autonomy, or self-determination, in the situation where they are no longer able to exercise this right on their own. In this paper we question this justification, by arguing that the most commonly suggested moral reasons for allowing and encouraging people to make their own choices seem not to apply when the patient’s decision-making is merely hypothetical. We end with some brief sketches of possible alternative ways of justifying the Substituted Judgment Standard. (shrink)

A very common but untested assumption is that potential children would consent to be exposed to the harms of existence in order to experience its benefits. And so, would-be parents might appeal to the following view: Procreation is all-things-considered permissible, as it is morally acceptable for one to knowingly harm an unconsenting patient if one has good reasons for assuming her hypothetical consent—and procreators can indeed reasonably rely on some notion of hypothetical consent. I argue that this view (...) is in error. My argument appeals to a consent-based version of anti-natalism advanced by Seana Valentine Shiffrin. Anti-natalism is the view that it is always wrong to bring people into existence. While, like Shiffrin, I stop short of advocating a thoroughgoing anti-natalism, I nevertheless argue that procreators cannot appeal to hypothetical consent to justify exposing children to the harms of existence. I end by suggesting a more promising route by which this justification might be achieved. (shrink)

The hypothetical syllogism is invalid in standard interpretations of conditional sentences. Many arguments of this sort are quite compelling, though, and you can wonder what makes them so. I shall argue that it is our parsimony in regard to connections among events and states of affairs. All manner of things just might, for all we know, be bound up with one another in all sorts of ways. But ordinarily it is better, being simpler, to assume they are unconnected. In (...) so doing, we jump to the conclusions of some compelling but invalid arguments. (shrink)

Abstract:Recently, the idea that every hypothetical imperative must somehow be ‘backed up’ by a prior categorical imperative has gained a certain influence among Kant interpreters and ethicists influenced by Kant. Since instrumentalism is the position that holds that hypothetical imperatives can by themselves and without the aid of categorical imperatives explain all valid forms of practical reasoning, the influential idea amounts to a rejection of instrumentalism as internally incoherent. This paper argues against this prevailing view both as (...) an interpretation of Kant and as philosophical understanding of practical reason. In particular, it will be argued that many of the arguments that claim to show that hypothetical imperatives must be backed up by categorical imperatives mistakenly assume that the form of practical reasoning must itself occur as a premise within the reasoning. An alternative to this assumption will be offered. I will conclude that while instrumentalism may well be false, there is no reason to believe it is incoherent. (shrink)

The categorical imperative inherent in Kant’s ethics has had indubitable historical influence on societies worldwide whether in the form of laws, democracy or public deliberation. The Toronto Van Attack of 2018 and its subsequent legal trial is a case example that shows how the categorical imperative can be applied to assist in understanding the reasoning for the case’s guilty verdict. This paper will convey the applicability of the categorical imperative for examining criminal case studies by closing the gap between (...) ethical theory and practice. Such closure will be shown to assist in understanding why a perpetrator of a crime can be found guilty of following a hypothetical imperative to base their actions. The rationale for the verdict in this case will be shown to be based on the perpetrator’s responsibility in the form of maintaining autonomy despite having an autism diagnosis. The perpetrator will be shown to have acted on an irrational will and yet was treated in the legal sense as a rational individual. Such rationality was maintained despite complications with their autonomy in the form of relativism and ethical solipsism. (shrink)

The last few decades have given rise to the study of practical reason as a legitimate subfield of philosophy in its own right, concerned with the nature of practical rationality, its relationship to theoretical rationality, and the explanatory relationship between reasons, rationality, and agency in general. Among the most central of the topics whose blossoming study has shaped this field, is the nature and structure of instrumental rationality, the topic to which Kant has to date made perhaps the largest contribution, (...) under the heading of his treatment of hypothetical imperatives. (shrink)

In this essay I argue against the idea that modeling in science is analogous to fiction making in literary works by pointing out that a typical move in the former, which is widely acknowledged in philosophy literature as a signal for fictionalization, is never present in works of fiction. I further argue that the reason for such a disparity is profound and profoundly against conceiving modeling as fictionalization. I then explain the difference between the hypothetical and the fictional, and (...) argue that modeling in science belongs to the former. (shrink)

Hájek (Erkenntnis 70(2):211–235, 2009) argues that probabilities cannot be the limits of relative frequencies in counterfactual infinite sequences. I argue for a different understanding of these limits, drawing on Norton’s (Philos Sci 79(2):207–232, 2012) distinction between approximations (inexact descriptions of a target) and idealizations (separate models that bear analogies to the target). Then, I adapt Hájek’s arguments to this new context. These arguments provide excellent reasons not to use hypothetical frequencies as idealizations, but no reason not to use them (...) as approximations. (shrink)

The hypothetical notion of consequence is normally understood as the transmission of a categorical notion from premisses to conclusion. In model-theoretic semantics this categorical notion is 'truth', in standard proof-theoretic semantics it is 'canonical provability'. Three underlying dogmas, (I) the priority of the categorical over the hypothetical, (II) the transmission view of consequence, and (III) the identification of consequence and correctness of inference are criticized from an alternative view of proof-theoretic semantics. It is argued that consequence is a (...) basic semantical concept which is directly governed by elementary reasoning principles such as definitional closure and definitional reflection, and not reduced to a categorical concept. This understanding of consequence allows in particular to deal with non-wellfounded phenomena as they arise from circular definitions. (shrink)

In this paper we propoee a logic programming language which supports hypothetical updates together with integrity constraints. The language makes use of a revision mechanism, which is needed to restore consistency when an update violates some integrity constraint. The revision policy adopted is based on the simple idea that more recent information is preferred to earlier one. We show how this language can be used to represent and perform several types of defeasible reasoning. We develop a logical characterization (...) of the language in a three-valued conditional logic, by introducing a completion construction. We show that the operational semantics is sound and complete with respect to the completion construction. (shrink)

What level of government subsidy of higher education is justified, in what form, and for what reasons? We answer these questions by applying the hypothetical insurance approach, originally developed by Ronald Dworkin in his work on distributive justice. On this approach, when asking how to fund and deliver public services in a particular domain, we should seek to model what would be the outcome of a hypothetical insurance market: we stipulate that participants lack knowledge about their specific resources (...) and risks, and ask what insurance contracts they would take out to secure different types of benefit and protection in the domain in question. The great benefit of the hypothetical insurance approach is that it allows us to take apparently intractable questions about interpersonal distribution and transform them into questions about intrapersonal distributions: that is, questions about how an individual would choose to distribute risks and resources across the various lives that they might end up living, in light of their individual ambitions and preferences. Applying this approach to higher education, we argue that the UK model of higher education funding in which the costs of an individual's higher education are shared between general taxation and the individual herself, with the latter element to be paid retrospectively through an income-contingent state-backed loan, is vindicated as just. In particular, we argue that it is more just than alternatives such as a graduate tax, full funding through general taxation, and full privatisation. (shrink)

Scientific reasoning represents complex argumentation patterns that eventually lead to scientific discoveries. Social epistemology of science provides a perspective on the scientific community as a whole and on its collective knowledge acquisition. Different techniques have been employed with the goal of maximization of scientific knowledge on the group level. These techniques include formal models and computer simulations of scientific reasoning and interaction. Still, these models have tested mainly abstract hypothetical scenarios. The present thesis instead presents data-driven approaches (...) in social epistemology of science. A data-driven approach requires data collection and curation for its further usage, which can include creating empirically calibrated models and simulations of scientific inquiry, performing statistical analyses, or employing data- mining techniques and other procedures. -/- We present and analyze in detail three co-authored research projects on which the thesis’ author was engaged during her PhD. The first project sought to identify optimal team composition in high energy physics laboratories using data-mining techniques. The results of this project are published in (Perović et al. 2016), and indicate that projects with smaller numbers of teams and team members outperform bigger ones. In the second project, we attempted to determine whether there is an epistemic saturation point in experimentation in high energy physics. The initial results from this project are published in (Sikimić et al. 2018). In the thesis, we expand on this topic by using computer simulations to test for biases that could induce scientists to invest in projects beyond their epistemic saturation point. Finally, in previous examples of data-driven analyses, citations are used as a measure of epistemic efficiency of projects in high energy physics. In order to additionally justify and analyze the usage of this parameter in their data-driven research, in the third project Perović & Sikimić (2019) analyzed and compared inductive patterns in experimental physics and biology with the reliability of citation records in these fields. They conclude that while citations are a relatively reliable measure of efficiency in high energy physics research, the same does not hold for the majority of research in experimental biology. -/- Additionally, contributions of the author that are for the first time published in this theses are: (a) an empirically calibrated model of scientific interaction of research groups in biology, (b) a case study of irregular argumentation patterns in some pathogen discoveries, and (c) an introductory discussion of the benefits and limitations of data- driven approaches to the social epistemology of science. Using computer simulations of an empirically calibrated model, we demonstrate that having several levels of hierarchy and division into smaller research sub-teams is epistemically beneficial for researchers in experimental biology. We also show that argumentation analysis in biology represents a good starting point for further data-driven analyses in the field. Finally, we conclude that a data-driven approach is informative and useful for science policy, but requires careful considerations about data collection, curation, and interpretation. (shrink)

I defend the claim that Kant held a wide-scope view of hypothetical imperatives, against objections raised by Mark Schroeder [2005]. There is an important objection, now commonly known as the ‘bootstrapping’ problem, to the alternative, narrow-scope, view which Schroeder attributes to Kant. Schroeder argues that Kant has sufficient resources to reply to the bootstrapping problem, and claims that this leaves us with no good reason to attribute to Kant the wide-scope view. I show that Schroeder's Kantian reply to the (...) bootstrapping problem cannot fully answer it. Schroeder also offers three main textual arguments for attributing to Kant the narrow-scope view: from Kant's claim that the moral imperative is unique in virtue of its categoricity, from Kant's distinction between ‘problematic’ and ‘assertoric’ hypothetical imperatives, and from Kant's conception of analyticity together with his claim that hypothetical imperatives are analytic. I argue that each of these views can be understood as cohering with the.. (shrink)

The dispute between Kantians and Humeans over whether practical reason can justify moral reasons for all agents is often characterized as a debate over whether reasons are hypothetical or categorical. Instead, this debate must be understood in terms of the distinction between agent-neutral and agent-relative reasons. This paper considers Alan Gewirth’s Reason and Morality as a case study of a Kantian justification of morality focused on deriving categorical reasons from hypothetical reasons. The case study demonstrates first, the possibility (...) of categorical agent-relative reasons, and second, that inattention to this possibility has caused considerable confusion in the debate between Kantians and Humeans. (shrink)