The atheist who begins to argue his case by saying, ‘Suppose there is an omniscient Being of the sort in which Christians believe ...’ is employing a very familiar move in argumentation. However, most books on argumentation theory ignore ‘suppositions’ completely. Searle omits suppositions entirely from his taxonomy of speech acts and this appears to lead to a similar omission in Speech Acts in Argumentative Discussions by van Eemeren and Grootendorst.This paper argues that ‘suppositional argument’ is elegant, powerful and (...) extremely common, that the correct way to understand it is based on Gottlob Frege's distinction between ‘asserted’ and ‘unasserted’ propositions and hence that suppositions are neither assertions nor (and this is more important) assertives. The paper discusses the connections between suppositions and conditionals; it argues that argumentation theory which ignores suppositions is systematically misleading; and it concludes by indicating some possible developments in argumentation theory. (shrink)

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)

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)

In this paper, I will show that the Miracle Argument is unsound if one assumes a certain form of transient underdetermination. For this aim, I will first discuss and formalize several variants of underdetermination, especially that of transient underdetermination, by means of measure theory. I will then formalize a popular and persuasive form of the Miracle Argument that is based on "use novelty". I will then proceed to the proof that the miracle argument is unsound by means of a mathematical (...) example. Finally, I will expose two hidden presuppositions of the Miracle Argument that make it so immensely though deceptively persuasive. (shrink)

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)

Informal logicians recognise the frequent use of unstated assumptions; some (e.g. Fisher) also recognise entertained arguments and recommend a suppositional approach (such as Mackie's) to conditional statements. It is here argued that these two be put together to make argument diagrams more accurate and subtle. Philosophical benefits also accrue: insights into Jackson's apparent violations of modus tollens and contraposition and McGee's counterexamples to the validity of modus ponens.

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)

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)

No início do século XIV, Raimundo Lúlio, contrapondo-se aos mestres em Artes por ele identificados como averroistae, desenvolveria não menos que dois métodos resolutivos de inconsistência, a fim de refutar aquelas teses filosóficas que divergem da fé cristã. Um deles serve-se de silogismos contraditórios capazes de expressar a estrutura de um argumento ad hominem, ao passo que o outro nada mais é do que uma reductio ad impossibile elaborada com base em suposições contraditórias. In the early fourteenth century, Ramond Lully, (...) opposed to university philosophers whom he identified as averroistae, developed no less than two methods for the resolution of inconsistency, in order to refute philosophical theses which diverge from the Christian faith. The first of these uses contradictory syllogisms expressing the structure of an ad hominem argument, while the other is a reductio ad impossibile produced with contradictory suppositions. (shrink)

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)

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.

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 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)

Arguments have always played a central role within logic and philosophy. But little attention has been paid to arguments as a distinctive kind of discourse, with its own semantics and pragmatics. The goal of this essay is to study the mechanisms by means of which we make arguments in discourse, starting from the semantics of argument connectives such as `therefore'. While some proposals have been made in the literature, they fail to account for the distinctive anaphoric behavior (...) of `therefore', as well as uses of argument connectives in complex arguments, suppositional arguments, arguments with non-declarative conclusions, as well as arguments with parenthetical remarks. A comprehensive account of arguments requires imposing a distinctive tree-like structure on contexts. We show how to extend our account to accommodate modal subordination and and di fferent flavors of `therefore'. (shrink)

According to many forms of Externalism now popular in the Philosophy of Mind, the contents of our thoughts depend in part upon our physical or social milieu.1 These forms of Externalism leave unchallenged the thesis that the ~non-factive! attitudes we bear towards these contents are independent of physical or social milieu. This paper challenges that thesis. It is argued here that publicly forwarding a content as a supposition for the sake of argument is, under conditions not themselves guaranteeing the existence (...) of that state, sufficient for occupancy of the intentional state of supposing that content. Because a saying may literally create an intentional state, whether one is in such a state does not depend solely upon how things are within one’s skin. Rather, even leaving content fixed, the attitude borne toward that content depends in part upon what norms are in force in one’s milieu. (shrink)

It can often seem like the attitude we hold towards a conditional should be our attitude in the consequent on the supposition of the antecedent. Following by Williamson (Suppose and Tell: The Semantics and Heuristics of Conditionals. Oxford University Press, 2020), we call this The suppositional rule (SR). The Adams-style non-propositional theories of indicatives upholds some key implications of SR, allowing, for instance, our credence in a conditional to be the probability of the consequent given the antecedent. Williamson (Suppose (...) and Tell: The Semantics and Heuristics of Conditionals. Oxford University Press, 2020) has recently provided a series of inconsistency arguments against SR. He thereby intends to undermine non-propositional views as well as other rivals to his favoured material conditional account. I outline a strategy which theorists of all stripes can employ to avoid Williamson’s arguments. I then show how non-propositionalists can implement this strategy. I show how they can uphold SR when it is intuitively compelling, whilst allowing it to fail when it is not. (shrink)

Christina Lafont has argued that the early Heidegger's reflections on truth and understanding are incompatible with ‘the supposition of a single objective world’. This paper presents her argument, reviews some responses that the existing Heidegger literature suggests, and offers what I argue is a superior response. Building on a deeper exploration of just what the above ‘supposition’ demands, I argue that a crucial assumption that Lafont and Haugeland both accept must be rejected, namely, that different ‘understandings of Being’ can be (...) viewed as offering ‘rival perspectives’ on a common subject-matter. I develop this case by drawing on an alternative account of what a Heideggerian ‘understanding of Being’ might be like. (shrink)

Ramseyan humility is the thesis that we cannot know which properties realize the roles specified by the laws of completed physics. Lewis seems to offer a sceptical argument for this conclusion. Humean fundamental properties can be permuted as to their causal roles and distribution throughout spacetime, yielding alternative possible worlds with the same fundamental structure as actuality, but at which the totality of available evidence is the same. On the assumption that empirical knowledge requires evidence, we cannot know which of (...) these worlds is actual. However, Lewis also appeals to a range of familiar semantic principles when framing his argument, which leads some authors to suppose that he can also plausibly be interpreted as offering a purely semantic argument for humility in addition. In this paper I grant that these arguments are Lewisian, but argue that Lewis is also committed to a theory of mind that licenses a purely metaphysical argument for humility based on the idea that mental properties supervene on fundamental structure. Given that knowing which x is the F requires knowing that a is the F, the supposition that we could come to know which properties actually occupy the fundamental roles entails differences in mental properties between worlds with the same fundamental structure, violating supervenience. Humility follows right away, without any further epistemic or semantic principles. This argument is immune to almost every way of rebutting the sceptical and semantic arguments; conversely, almost every way of rebutting the metaphysical argument tells equally against the others. (shrink)

This new and expanded edition of The Logic of Real Arguments explains a distinctive method for analysing and evaluating arguments. It discusses many examples, ranging from newspaper articles to extracts from classic texts, and from easy passages to much more difficult ones. It shows students how to use the question 'What argument or evidence would justify me in believing P?', and also how to deal with suppositional arguments beginning with the phrase 'Suppose that X were the (...) case.' It aims to help students to think critically about the kind of sustained, theoretical arguments which they commonly encounter in the course of their studies, including arguments about the natural world, about society, about policy, and about philosophy. It will be valuable for students and their teachers in a wide range of disciplines including philosophy, law and the social sciences. (shrink)

This new and expanded edition of The Logic of Real Arguments explains a distinctive method for analysing and evaluating arguments. It discusses many examples, ranging from newspaper articles to extracts from classic texts, and from easy passages to much more difficult ones. It shows students how to use the question 'What argument or evidence would justify me in believing P?', and also how to deal with suppositional arguments beginning with the phrase 'Suppose that X were the (...) case.' It aims to help students to think critically about the kind of sustained, theoretical arguments which they commonly encounter in the course of their studies, including arguments about the natural world, about society, about policy, and about philosophy. It will be valuable for students and their teachers in a wide range of disciplines including philosophy, law and the social sciences. (shrink)

This new and expanded edition of The Logic of Real Arguments explains a distinctive method for analysing and evaluating arguments. It discusses many examples, ranging from newspaper articles to extracts from classic texts, and from easy passages to much more difficult ones. It shows students how to use the question 'What argument or evidence would justify me in believing P?', and also how to deal with suppositional arguments beginning with the phrase 'Suppose that X were the (...) case.' It aims to help students to think critically about the kind of sustained, theoretical arguments which they commonly encounter in the course of their studies, including arguments about the natural world, about society, about policy, and about philosophy. It will be valuable for students and their teachers in a wide range of disciplines including philosophy, law and the social sciences. (shrink)

Can fictional narration yield knowledge in a way that depends crucially on its being fictional? This is the hard question of literary cognitivism. It is unexceptional that knowledge can be gained from fictional literature in ways that are not dependent on its fictionality (e.g., the science in science fiction). Sometimes fictional narratives are taken to exhibit the structure of suppositional argument, sometimes analogical argument. Of course, neither structure is unique to narratives. The thesis of literary cognitivism would be supported (...) if some novels exhibit a cogent and special argument structure restricted to fictional narratives. I contend that this is the case for a kind of transcendental argument. The reason is the inclusion and pattern of occurrence of the predicate ‘believable’ in the schema. Believability with respect to fictional stories is quite a different thing than it is with respect to nonfictional stories or anything else. (shrink)

ABSTRACT: In this paper I argue (i) that the hypothetical arguments about which the Stoic Chrysippus wrote numerous books (DL 7.196) are not to be confused with the so-called hypothetical syllogisms" but are the same hypothetical arguments as those mentioned five times in Epictetus (e.g. Diss. 1.25.11-12); and (ii) that these hypothetical arguments are formed by replacing in a non-hypothetical argument one (or more) of the premisses by a Stoic "hypothesis" or supposition. Such "hypotheses" or suppositions differ (...) from propositions in that they have a specific logical form and no truth-value. The reason for the introduction of a distinct class of hypothetical arguments can be found in the context of dialectical argumentation. The paper concludes with the discussion of some evidence for the use of Stoic hypothetical arguments in ancient texts. (shrink)

As a discipline, logic is arguably constituted of two main sub-projects: formal theories of argument validity on the basis of a small number of patterns, and theories of how to reduce the multiplicity of arguments in non-logical, informal contexts to the small number of patterns whose validity is systematically studied . Regrettably, we now tend to view logic 'proper' exclusively as what falls under the first sub-project, to the neglect of the second, equally important sub-project. In this paper, I (...) discuss two historical theories of argument formalization: Aristotle's syllogistic theory as presented in the "Prior Analytics", and medieval theories of supposition. They both illustrate this two-fold nature of logic, containing in particular illuminating reflections on how to formalize arguments . In both cases, the formal methods employed differ from the usual modern technique of translating an argument in ordinary language into a specially designed symbolism, a formal language. The upshot is thus a plea for a broader conceptualization of what it means to formalize. Pode-se dizer que, enquanto disciplina, a lógica é caracterizada por dois subprojetos: teorias formais da validade de argumentos, baseadas em um número reduzido de esquemas e padrões formais, e teorias de como reduzir a multiplicidade de argumentos em contextos informais, não lógicos, ao pequeno número de padrões formais cuja validade é estudada de maneira sistemática no âmbito do primeiro subprojeto. O segundo subprojeto corresponde à noção de formalização de argumentos. Infelizmente, a tendência atual é de considerar como sendo a lógica propriamente dita exclusivamente o que se encaixa no primeiro subprojeto, em detrimento do segundo subprojeto, igualmente importante. Neste artigo, duas teorias históricas sobre a formalização de argumentos são analisadas: a teoria da silogística apresentada por Aristóteles nos "Primeiros Analíticos" e teorias medievais da suposição. Ambas ilustram o caráter duplo da lógica, que envolve dois subprojetos distintos, e contêm reflexões sofisticadas sobre como formalizar argumentos. Em ambos os casos, os métodos formais utilizados se diferenciam dos métodos atuais de tradução de um argumento em linguagem vernacular para um simbolismo especialmente formulado, ou seja, uma linguagem formal. Em conclusão, o artigo pode ser visto como a defesa de uma conceitualização mais abrangente do que significa 'formalizar' um argumento. (shrink)

The metaphor “ARGUMENT IS WAR” looms large in the conceptualist and experientialist approach of CitationLakoff and Johnson (1980). Despite extensive discussion of this metaphor by critics and supporters of Lakoff and Johnson, it has so far escaped serious scrutiny on several key points. English-speakers can identify verbal exchanges as arguments without resort to metaphorical comparisons or transfers, and speakers' use of war metaphors to characterize verbal dispute depends on conventional understandings rather than personal experience of war or of other (...) kinds of physical struggle. Much of the evidence for Lakoff and Johnson's claims—a culture that metaphorizes argument as dance; the historical and personal priority of force over verbal dispute; the influence of metaphor on action; even the experience supposedly shaping source domains—depends on supposition and ungrounded assertion. In making sense of how people use this metaphor, the discourse-based program elaborated by Naomi CitationQuinn (1991, Citation1997) carries analysis further than a purely conceptualist approach. (shrink)

The 'substitution argument' purports to demonstrate the falsity of Russellian accounts of belief-ascription by observing that, e.g., these two sentences: (LC) Lois believes that Clark can fly. (LS) Lois believes that Superman can fly. could have different truth-values. But what is the basis for that claim? It seems widely to be supposed, especially by Russellians, that it is simply an 'intuition', one that could then be 'explained away'. And this supposition plays an especially important role in Jennifer Saul's defense of (...) Russellianism, based upon the existence of an allegedly similar contrast between these two sentences: (PC) Superman is more popular than Clark. (PS) Superman is more popular than Superman. The latter contrast looks pragmatic. But then, Saul asks, why shouldn't we then say the same about the former? The answer to this question is that the two cases simply are not similar. In the case of (PC) and (PS), we have only the facts that these strike us differently, and that people will sometimes say things like (PC), whereas they will never say things like (PS). By contrast, there is an argument to be given that (LS) can be true even if (LC) is false, and this argument does not appeal to anyone's 'intuitions'. The main goal of the paper is to present such a version of the substitution argument, building upon the treatment of the Fregan argument against Russellian accounts of belief itself in "Solving Frege's Puzzle". A subsidiary goal is to contribute to the growing literature arguing that 'intuitions' simply do not play the sort of role in philosophical inquiry that so-called 'experimental philosophers' have supposed they do. (shrink)

The Reflection Principle can be defended with a Diachronic Dutch Book Argument (DBA), but it is also defeated by numerous compelling counter-examples. It seems then that Diachronic DBAs can lead us astray. Should we reject them en masse—including Lewis’s Diachronic DBA for Conditionalization? Rachael Briggs’s “suppositional test” is supposed to differentiate between Diachronic DBAs that we can safely ignore (including the DBA for Reflection) and Diachronic DBAs that we should find compelling (including the DBA for Conditionalization). I argue that (...) Brigg’s suppositional test is wrong: it sets the bar for coherence too high and places certain cases of self-doubt on the wrong side of the divide. Given that the suppositional test is unsatisfactory, we are left without any justification for discriminating between Diachronic DBAs and ought to reject them all—including the DBA for Conditionalization. (shrink)

The private language arguments exemplify the analogy: private ownership of experience; private knowledge of experience; private ostensive definition; the mereological fallacy; the 'beetle in the box'; and so on. The supposition that Wittgenstein's philosophy is primarily therapeutic obscures the extent to which therapy is only possible if one attains a grasp of the logical geography of the relevant part of the philosophical landscape. The analogy between clarifying and eradicating philosophical confusion and treating a disease is often linked to a (...) related analogy that Wittgenstein drew in five different contexts in the 1930s, namely between his methods in philosophy and the method of treating mental illness by psychoanalysis. The idea of a private language is incoherent precisely because it fails to distinguish imagining a justification for using a word and justifying the use of a word in one's imagination. (shrink)

This work aims to querying what are the limits of philosophical argumentation established by Plato and the distance of those limits in relation to Aristotle’s and later thinkers’ thoughts. The supposition here defended concerns to the fact that, for Plato, what really changes in the argumentations is that the definition becomes delimitation, that the logic replaces rethoric, that the demonstration becomes persuasion, if assumed the hermeneutical links that the thought and the language are subjected to.

This work aims to querying what are the limits of philosophical argumentation established by Plato and the distance of those limits in relation to Aristotle’s and later thinkers’ thoughts. The supposition here defended concerns to the fact that, for Plato, what really changes in the argumentations is that the definition becomes delimitation, that the logic replaces rethoric, that the demonstration becomes persuasion, if assumed the hermeneutical links that the thought and the language are subjected to.

This work aims to querying what are the limits of philosophical argumentation established by Plato and the distance of those limits in relation to Aristotle’s and later thinkers’ thoughts. The supposition here defended concerns to the fact that, for Plato, what really changes in the argumentations is that the definition becomes delimitation, that the logic replaces rethoric, that the demonstration becomes persuasion, if assumed the hermeneutical links that the thought and the language are subjected to.

The paper shows that it is possible to obtain a "slingshot" result in Gödel's theory of positiveness in the presence of the theorem of the necessary existence of God. In the context of the reconstruction of Gödel's original "slingshot" argument on the suppositions of non-Fregean logic, this is a natural result. The "slingshot" result occurs in sufficiently strong non-Fregean theories accepting the necessary existence of some entities. However, this feature of a Gödelian theory may be considered not as a trivialisation, (...) but as an intended consequence of Gödel's ontotheological views. (shrink)

It is still commonly supposed that Descartes based his argument for the mind-body distinction on the law of the indiscernibility of identicals. I argue that this interpretation is very unlikely to be correct. I explain three contemporary versions of this interpreta- tion and say why I reject it. Basically, use of this law for Descartes’s conclusion would require reference to human bodies or else the supposition, for the purpose of the argument, of reference to human bodies. But at the time (...) Descartes formulated his argument, he would not have allowed either. Instead, I amend a different interpretation which others have found, and briefly defend it against one famous objection. (shrink)

Disagreements about the success of any given argument often arise because the suppositions of the critic differ from the suppositions of the author of the argument. In maintaining the plausibility of a metaethical argument for theism against the objections articulated by Stephen J. Sullivan, I will probe our differing suppositions with regard to the relation of theological to naturalistic metaethical theories, the starting point for the metaethical argument for theism, and the relation of the qualities of God's will to our (...) obligation to obey God. (shrink)

RÉSUMÉ: Utilisant ce qu'on appelle l'argument du lance-pierres, Davidson soutient que la théorie correspondantiste de la vérité est intenable. Cet argument dépend de deux présuppositions, dont l'une est qu'une phrase vraie ne devrait pas, par substitution de termes singuliers coréférentiels, en venir à correspondre à quelque chose de différent. Je propose dans cet article un argument nouveau pour montrer que cette supposition n'est pas plausible, particulièrement lorsqu'elle s'applique à des énoncés d'identité, ceux-là mêmes dont dépend pour sa formulation l'argument du (...) lance-pierres. (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)

1. In general we agree to recognize the existence, if not the methodological fertility or epistemological legitimacy, of a "rationalist model," at least when we refer to what economists do when they offer explanations.1 However two remarks must be made about this. First, it must be emphasized that this model is not unique, but generic: in fact, it is more a family of models of which the fundamental theoretical suppositions are susceptible to large variations. There are here, as it were, (...) several possible axiomatic bases. One formulation is, for example and to use von Mises's term, praxeological (axed on means/end relation). Another emphasizes the preference/constraint relation (Harsanyi). Other contrasting models are those putting forward the maximization of expected utility (von Neumann-Morgenstern) and those making the satisficing hypothesis (Simon). Second, however, it must also be said that philosophers of science do not really agree on what is asserted by the "principle of rationality" or on what is its status. For example, Popper (1982) made it a minimal empirical hypothesis, or practically empty, and denied, furthermore, that it was a universally valid psychological law. Hempel (1965) did not hesitate, in contrast, to make it a law of experimental psychology which would play an implicit or explicit role in any adequate and complete explanation of behaviour or action in social sciences or history. Dray, to cite another classic author (cf. Dray 1957), made this principle the base for the explanations of historians, but denied it the status of a nomological proposition. In consequence, it is difficult to proceed as if there were a theoretical consensus among researchers when they base their explanatory arguments on the rationality of agents. This is clearly not the case. However, Raymond Boudon is right to consider the "rationalist model" an extension to all the social sciences of the model of explanation which is found at the base of what has been called the "marginalist revolution" in economics.. (shrink)

In Reason, Truth and History, Putnam provides an influential argument for the materialist view that the supposition that we are all “actually” brains in a vat [BIV’s] is “necessarily false”. Putnam admits that his argument, inspired by insights in Wittgenstein’s later views, is “unusual”, but he is certain that it is a correct. He argues that the claim that we are BIV’s is self-refuting because, if we actually are BIV’s, then we cannot refer to real physical things like vats. Although (...) the present author agrees, fundamentally, with Heidegger’s view that we are essentially “in a world”, and, therefore, with Putnam’s conclusion that we cannot possibly be BIV’s, the paper argues that Putnam’s argument is fallacious. The proper conclusion to draw from Putnam’s argument is that asserting that one is a BIV is beyond the limits of a BIV’s language. That is, Putnam only shows that if we actually are BIV’s, then we cannot think or assert either that we are or that we are not BIV’s. It does not show that we are not “actually” BIV’s. The cogency of this criticism is illustrated with a concrete “science-fiction” example. (shrink)

Aquinas’ so-called “Intellectus essentiae Argument” for the distinction between being and essence is notoriously suspect, including among defenders of Aquinas’ distinction. For the paper in this volume, I take as my starting point the recent defense of the argument by Fr. Lawrence Dewan, O.P. Fr. Dewan’s project is unsuccessful. Pointing out some shortcomings in his readings allows me to take up his call to highlight the “formal” or “quidditative side” of Aquinas’ metaphysics, in this case in regards to the proofs (...) of the “real distinction.” Accordingly, the second half of this paper sets forth a way in which the famous “Intellectus essentiae Argument” of De Ente et Essentia 4 can succeed as a proof of the real distinction. Aquinas’ argument presupposes the prior real distinction between essence and supposit or individual substance. Esse is the ontological component that makes true our judgments that substances actually are: Obama exists. By contrast, this “truth-maker” cannot be predicated of humanity, although it is in Obama as really distinct from him. If Aquinas’ reasoning in this most contentious of his proofs can be saved, so, perhaps, can most of his other proofs. (shrink)

Kant’s remark that the first Kritik should be read as a treatise on method rather than a system of doctrine lends support to recent forays against his theory of proof, for the comment promotes the mistaken supposition that his method can be studied independently of his commitments in ontology and other areas. Irony infects the criticisms in question because they set transcendental logic against a standard that Kant repudiates. The point will be illustrated by showing how Kant anticipates and blunts (...) a strong attack against his position on method. (shrink)

Formerly a spectral apparition that haunted behaviorism and provided a puzzle about our knowledge of other minds, the inverted spectrum possibility has emerged as an important challenge to functionalist accounts of qualia. The inverted spectrum hypothesis raises the possibility that two individuals might think and behave in the same way yet have different qualia. The traditional supposition is of an individual who has a subjective color spectrum that is inverted with regard to that had by other individuals. When he looks (...) at red objects, this individual has the qualia normally produced in others by blue objects. And when presented with a blue object, this individual experiences qualia that most persons experience only when presented with red objects. And so forth - the Invert's color spectrum is the inverse of normal; there are systematic inter-subjective differences in qualia. (shrink)

Indispensability arguments occupy a prominent role in discussions of mathematical realism. While different versions of these arguments are discussed in the literature, their general structure remains the same. These arguments contend that insofar as reference to mathematical objects is indispensable to science, we are committed to the existence of these ‘objects’. Unsurprisingly, much of the debate concerning indispensability arguments focuses on the crucial contention that mathematical objects are indispensable to science. For these arguments to provide (...) support for mathematical realism, what we require are some compelling examples of mathematics playing an indispensable role in science. Towards this end, Alan Baker has supplied an example in which mathematics appears to be indispensable to a scientific explanation, what has come to be called the “Cicada MES”. This example has been the subject of much criticism, most notably that it depends on an unsupported empirical supposition. Recently, Baker proposed a number of revisions to the Cicada MES that aim to address some of these criticisms. In this paper, I argue that while Baker’s revisions go some way towards mitigating prominent criticisms of the Cicada MES, the underlying problem with the explanation remains. I argue that his revisions actually go in the wrong direction mathematically and empirically. In contrast, I propose a new Cicada MES. This new version accomplishes Baker’s goals and responds to the central objection to the explanation. It invokes a mathematical principle that plays a unifying role in the explanation, which makes providing adequate nominalist surrogates more difficult. And, more importantly, it accommodates an empirically grounded explanation of the phenomenon to be explained. Consequently, this new Cicada MES provides what proponents of indispensability arguments require, a compelling example of mathematics playing an indispensable role in science. (shrink)

In De Interpretatione 9 Aristotle considers the proposition that everything that is or comes to be, is or comes to be of necessity. From the supposition that this is so, he draws the following consequence: ‘[In that case] there would be no need to deliberate or take trouble, [saying] that if we do this there will be so and so, and if we do not do this there will not be so and so’. Finding this result absurd, he rejects the (...) supposition and concludes that some events or states of affairs are contingent. (shrink)

Examples involving infinite suspended chains or infinite trains are sometimes used to defend perceived weaknesses in traditional cosmological arguments. In this article, we distinguish two versions of the cosmological argument, suggest that such examples can only be relevant if it is one specific type of cosmological argument that is being considered, and then criticize the use of such examples in this particular type of cosmological argument. Our criticism revolves around a discussion of what it means to call a system (...) closed, and what it means to call an explanation complete. Our analysis makes no suppositions about the nature of the infinite, and is therefore independent of many of the issues around which contemporary discussions of the cosmological argument have tended to revolve. (shrink)

Scientific risk evaluations are constructed by specific evidence, value judgements and biological background assumptions. The latter are the framework-setting suppositions we apply in order to understand some new phenomenon. That background assumptions co-determine choice of methodology, data interpretation, and choice of relevant evidence is an uncontroversial claim in modern basic science. Furthermore, it is commonly accepted that, unless explicated, disagreements in background assumptions can lead to misunderstanding as well as miscommunication. Here, we extend the discussion on background assumptions from basic (...) science to the debate over genetically modified (GM) plants risk assessment. In this realm, while the different political, social and economic values are often mentioned, the identity and role of background assumptions at play are rarely examined. We use an example from the debate over risk assessment of stacked genetically modified plants (GM stacks), obtained by applying conventional breeding techniques to GM plants. There are two main regulatory practices of GM stacks: (i) regulate as conventional hybrids and (ii) regulate as new GM plants. We analyzed eight papers representative of these positions and found that, in all cases, additional premises are needed to reach the stated conclusions. We suggest that these premises play the role of biological background assumptions and argue that the most effective way toward a unified framework for risk analysis and regulation of GM stacks is by explicating and examining the biological background assumptions of each position. Once explicated, it is possible to either evaluate which background assumptions best reflect contemporary biological knowledge, or to apply Douglas' 'inductive risk' argument. (shrink)

Since the late 1960s, the legal doctrine of consent has occasionally been subject to severe criticism from within the bioethical discourse. The criticism was often based on observations indicating that consents and refusals, which had been considered valid from legal or institutional points of view, had frequently failed to reflect genuinely autonomous decision making, hence genuinely autonomous choices.This has led several critics to conclude that informed consent is a legal fiction. To clarify the concept, a legal fiction is a supposition (...) of fact taken to be true by the courts of law, irrespective of whether it is true or not, and even though it might not be true .1 What these critics probably meant to say was that the law deems any person who has given a legally valid consent to be genuinely task specifically autonomous, regardless of whether this is true or not and even though it might not be true. In other words, informed consent is a legal fiction, since it presupposes—that is, claims to reflect—genuine task specific autonomy, however baselessly.It was precisely this potentially embarrassing conclusion that prompted Faden and Beauchamp to develop a brilliant and remarkably effective argument in defence of the legal doctrine of consent. In their seminal work, AHistory and Theory of Informed Consent, they indeed acknowledged that effective consent often fails to be compatible with autonomous authorisation . Indeed, they recognised that effective consent does not necessarily entail autonomous authorisation. They argued, however, that the former is not a legal fiction, since it does not presuppose the …. (shrink)

The essay presents Saul Kripke's argument for mind/body-dualism and makes the suppositions explicit on which it rests. My claim, inspired by Richard Boyd, is that even if one of Kripke’s central suppositions - the principle of necessity of identities using rigid designators - is shared by the non-traditional identity theorist, it is still possible for her to rebut Kripke’s dualism.