Hypotheticals, conditionals, and their connecting relation, implication, dramatically changed their meanings during the nineteenth and early part of the twentieth century. Modern logicians ordinarily do not distinguish between the terms hypothetical and conditional. Yet in the late nineteenth century their meanings were quite different, their ties to the implication relation either were unclear, or the implication relation was used exclusively as a logical operator. I will trace the development of implication as an inference operator from these earlier notions (...) into the first third of the twentieth century using as the starting point the ideas primarily of R. Whately and W. Hamilton before discussing the work of the transitional logicians, A. De Morgan and G. Boole on these topics. Then we discuss the relevant views of four prominent but relatively unknown nineteenth century British logicians, W.E. Johnson, J.N. Keynes, E.E.C. Jones, and H. MacColl, as well as those of the more influential logicians, W.S. Jevons and J. Venn, closing with a section on ‘implication as inference’ where we explore some key ideas of B. Russell and sketch the work of D. Hilbert, P. Hertz, and G. Gentzen who together are responsible for the development of the modern ideas related to the subjects of this paper. (shrink)

The use of high hypothetical payoffs has been justified by the realism and relevance of large monetary consequences and by the impracticality of making high cash payments. We argue that subjects may not be able to imagine how they would behave in high payoff situations.

The use of high hypothetical payoffs has been justified by the realism and relevance of large monetary consequences and by the impracticality of making high cash payments. We argue that subjects may not be able to imagine how they would behave in high payoff situations.

In this article, I present a schema for generating counterexamples to the argument form known as Hypothetical Syllogism with indicative conditionals. If my schema for generating counterexamples to HS works as I think it does, then HS is invalid for indicative conditionals.

Moti Mizrahi (2013) presents some novel counterexamples to Hypothetical Syllogism (HS) for indicative conditionals. I show that they are not compelling as they neglect the complicated ways in which conditionals and modals interact. I then briefly outline why HS should nevertheless be rejected.

Boethius' treatise De Hypotheticis Syllogismis provided twelfth-century philosophers with an introduction to the logic of conditional and disjunctive sentences but this work is the only part of the logica vetus which is no longer studied in the twelfth century. In this paper I investigate why interest in Boethius acount of hypothetical syllogisms fell off so quickly. I argue that Boethius' account of compound sentences is not an account of propositions and once a proper notion of propositionality is available the (...) argument forms accepted by Boethius are seen to be incoherent. It was Peter Abaelard who first understood the nature of propositionality and propositional connectives and used this to criticise Boethius' claims in De Hypothetics Syllogismis. In place Boethius' confusion Abaelard offered a simple and correct account of the hypothetical syllogism. (shrink)

The debate over Hypothetical Syllogism is locked in stalemate. Although putative natural language counterexamples to Hypothetical Syllogism abound, many philosophers defend Hypothetical Syllogism, arguing that the alleged counterexamples involve an illicit shift in context. The proper lesson to draw from the putative counterexamples, they argue, is that natural language conditionals are context-sensitive conditionals which obey Hypothetical Syllogism. In order to make progress on the issue, I consider and improve upon Morreau’s proof of the invalidity (...) of Hypothetical Syllogism. The improved proof relies upon the semantic claim that conditionals with antecedents irrelevant to the obtaining of an already true consequent are themselves true. Moreover, this semantic insight allows us to provide compelling counterexamples to Hypothetical Syllogism that are resistant to the usual contextualist response. (shrink)

ABSTRACT: In antiquity we encounter a distinction of two types of hypothetical syllogisms. One type are the ‘mixed hypothetical syllogisms’. The other type is the one to which the present paper is devoted. These arguments went by the name of ‘wholly hypothetical syllogisms’. They were thought to make up a self-contained system of valid arguments. Their paradigm case consists of two conditionals as premisses, and a third as conclusion. Their presentation, either schematically or by example, varies (...) in different authors. For instance, we find ‘If (it is) A, (it is) B; if (it is) B, (it is) C; therefore, if (it is) A, (it is) C’. The main contentious point about these arguments is what the ancients thought their logical form was. Are A, B, C schematic letters for terms or propositions? Is ‘is’, where it occurs, predicative, existential, or veridical? That is, should ‘A esti’ be translated as ‘it is an A’, ‘A exists’, ‘As exist’ or ‘It is true/the case that A’? If A, B, C are term letters, and ‘is’ is predicative, are the conditionals quantified propositions or do they contain designators? If one cannot answer these questions, one can hardly claim to know what sort of arguments the wholly hypothetical syllogisms were. In fact, all the above-mentioned possibilities have been taken to describe them correctly. In this paper I argue that it would be mistaken to assume that in antiquity there was one prevalent understanding of the logical form of these arguments - even if the ancients thought they were all talking about the same kind of argument. Rather, there was a complex development in their understanding, starting from a term-logical conception and leading to a propositional-logical one. I trace this development from Aristotle to Philoponus and set out the deductive system on which the logic of the wholly hypothetical syllogisms was grounded. (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)

It is generally agreed that there are two kinds of indicative conditionals that do not contain conditional 'then.' There are hypothetical conditionals such as 'If Mary has done the groceries, there is beer in the fridge' and there are biscuit conditionals such as 'If you are thirsty, there is beer in the fridge.' There is also broad consensus that we cannot find an analogous distinction between hypothetical and biscuit conditionals within indicative conditionals that (...) do feature 'then.' Conditionals containing 'then,' it is assumed, are uniformly read as hypothetical conditionals. In this article, I shall argue that there are biscuit conditionals featuring 'then.' This result, I take it, is not only interesting on its own. It also puts pressure on the popular view that conditional 'then' triggers the presupposition that in some situations in which the conditional's antecedent is not true, its consequent is not true either. (shrink)

This article starts by examining the appeal to hypothetical consent as used by law and economics writers. I argue that their use of this kind of argument has no moral force whatever. I then briefly examine, through some remarks on Rawls and Scanlon, the conditions under which such an argument would have moral force. Finally, I bring these considerations to bear to criticize the argument of judge Frank Easterbrook's majority opinion in Flamm v. Eberstadt.

The conditional interpretation of general categorical statements like ‘All men are animals’ as universally quantified material conditionals ‘For all x, if x is F, then x is G’ suggests that the logical structure of law statements is conditional rather than categorical. Disregarding the problem that the universally quantified material conditional is trivially true whenever there are no xs that are F, there are some reasons to be sceptical of Frege’s equivalence between categorical and conditional expressions. -/- Now many philosophers (...) will claim that the material conditional interpretation of laws statements, dispositions ascriptions, or any causal claim is generally accepted as wrong and outdated. Still, there seem to be some basic logical assumptions that are shared by most of the participants in the debate on causal matters which at least stems from the traditional truth functional interpretation of conditionals. This is indicated by the vocabulary in the philosophical debate on causation, where one often speaks of ‘counterfactuals’, ‘possible worlds’ and ‘necessity’ without being explicit on whether or to what extent one accepts the logical-technical definition of these notions. To guarantee a non-Humean and non-extensional approach to causal relations, it is therefore important to be aware of the logical and metaphysical implications of the technical vocabulary. -/- In this paper we want to show why extensional logic cannot deal with causal relations. Via a logical analysis of law-like statements ‘All Fs are Gs’ we hope to throw some new light on interrelated notions like causation, laws, induction, hypotheticality and modality. If successful, our analysis should be of relevance for a deeper understanding of any type of causal relations, whether we understand them to be laws, dispositions, singulars or categoricals. (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)

According to Woodward’s influential account of explanation, explanations have a counterfactual structure, and explanatory counterfactuals are analysed in terms of causal relations and interventions. In this paper, we provide a formal semantics of explanatory counterfactuals based on a Ramsey Test semantics of conditionals. Like Woodward’s account, our account is guided by causal considerations. Unlike Woodward’s account, it makes no reference to causal graphs and it also covers cases of explanation where interventions are impossible.

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.

This paper is concerned with an important variant reading discovered at the beginning of Book VIII of Aristotle’s _Physics_. The reading is found in J, the oldest manuscript of this work (Vind. phil. gr. 100, 9th c.): at VIII 1.250b13, J reads εἰ ἦν, “if it [_scil_. the movement] was”, instead of ἀεὶ ἦν, “it always was”, the only reading so far taken into account. Several early witnesses support J: E (Paris. gr. 1853, 10th c.), the Greek into Latin translation (...) by James of Venice (first half of the 12th c., _si erat_); the earliest Arabic version (_ap_. Jabir ibn Hayyan, انكنات, “if [the movement] was”). Such early sources thus agree as witnesses of a hypothetical premise concerning the eternity of cosmic motion against the standard vulgate text of the _Physics_. Once the if-reading at 250b13 is accepted, as opposed to the vulgate, Aristotle’s conclusion about the eternity of motion will apply not absolutely, but under the condition of the given premise that in no plausible way could motion have begun in time. The difference is important on several grounds. In particular, it fits better with the manner in which the argument is then developed by Aristotle throughout chapter 1 of _Phys_. VIII and with the parallel discussion about the eternity of the cosmos in _De caelo_ I 10 and _Metaphysics_ Λ 6. However, favouring the variant reading of J for _Phys_. 250b13 raises the problem of evaluating with special care the authority of manuscript J for the textual constitution of the _Physics_, which remains an open question for future scholarship. (shrink)

The focus of my dissertation is a general and comprehensive examination of Locke’s view of divine power. My basic argument is that John Locke is a theological voluntarist in his understanding of God’s creative and providential relationship with the world, including both the natural and moral order. As a voluntarist, Locke holds that God freely imposes both the physical and moral laws of nature onto creation by means of his will: this contrasts with the intellectualist perspective in which the laws (...) of nature emerge from the essences of things. For Locke, there are no intrinsically necessary laws in the created order: both physical and moral laws are arbitrary determinations of the divine will. While these laws are not intrinsically necessary, they are hypothetically necessary. Hypothetical necessity involves things that could have been otherwise, but which are necessary based on the supposition of a free action and other relevant conditions pertaining to the actor. Concerning God, we can understand hypothetical necessity in the following way: □ [ → Y]. X is a variable that ranges over a subset of contingent propositions about actions. ‘P’ is the proposition ‘God is perfect’. And Y is any proposition that is a necessary consequent of both X and P. In any possible world in which God performs X, it is the case that Y will obtain. Supposing that God decides to create beings like us, God must of necessity craft the moral laws of nature in a way that harmonizes with our nature. What grounds this necessity is that God must act consistently with the perfection of the divine nature: to give us a different law would be less than perfect. Furthermore, I argue that certain physical laws of nature – those that help to realize our nature – are also hypothetically necessary. (shrink)

The recent literature offers several models of the notion of matter of fact supposition1 revealed in the acceptance of the so-called indicative conditionals. Some of those models are qualitative [Collins 90], [Levi 96], [Stalnaker 84]. Other probabilistic models appeal either to infinitesimal probability or two place probability functions. Recent work has made possible to understand which is the exact qualitative counterpart of the latter probabilistic models. In this article we show that the qualitative notion of change that thus arises (...) is hypothetical revision, a notion previously axiomatized in [Arló-Costa 97] and [Arló-Costa & Thomason 96]. This notion is incompatible with AGM as well as with other standard methods of theory change. The way in which matter-of-fact supposition is modeled by hypothetical revision is illustrated via examples. The model is compared with other qualitative accounts of the notion of supposition encoded in two-place probability functions, with models of subjunctive supposition, as well as with some of the well know models of learning. Applications in knowledge representation and in the theory of games and decisions are summarized. (shrink)

What is the role of "teleological explanation" in aristotle's account of psychological and biological phenomena? this paper argues that it provides a way of understanding these phenomena which is not reducible to purely material explanation, And which allows for the possibility of a full material account of the conditions under which these phenomena occur. It also offers an alternative account of hypothetical necessity to that proposed by john cooper.

In previous published research (“Conditionals and Inferential Connections: A Hypothetical Inferential Theory,” Cognitive Psychology, 2018), we investigated experimentally what role the presence and strength of an inferential connection between a conditional’s antecedent and consequent plays in how people process that conditional. Our analysis showed the strength of that connection to be strongly predictive of whether participants evaluated the conditional as true, false, or neither true nor false. In this article, we re-analyse the data from our previous research, now (...) focussing on the semantics of conditionals rather than on how they are processed. Specifically, we use those data to compare the main extant semantics with each other and with inferentialism, a semantics according to which the truth of a conditional requires the presence of an inferential connection between the conditional’s component parts. (shrink)

This paper is about two controversial inference-patterns involving counterfactual or subjunctive conditionals. Given a plausible assumption about the truth-conditions of counterfactuals, it is shown that one can't go wrong in applying hypothetical syllogism (i.e., transitivity) so long as the set of worlds relevant for the conclusion is a subset of the sets of worlds relevant for the premises. It is also shown that one can't go wrong in applying antecedent strengthening so long as the set of worlds relevant (...) for the conclusion is a subset of that for the premise. These results are then adapted to Lewis's theory of counterfactuals. (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)

Kant famously distinguishes between the categorical imperative (CI) and hypothetical imperatives (HIs), which are instrumental norms. On the standard reading, Kant subscribes to the of HIs, which takes HIs to be consistency requirements that bind agents in exactly the same way whether or not agents are subject to CI and whether or not they conform their choices to CI. I argue that this reading cannot be squared with Kant's account of an agent's disposition, in particular his claim that cognition (...) of CI is a necessary condition of willing a maxim. I further argue that Kant could not accept an account of HIs as consistency requirements. Finally, I outline Kant's conception of HIs as non-disjunctive requirements that arise when and only when agents will permissible ends. This account can help recapture Kant's conception of the unity of rational norms. (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)

I propose an account of indicative conditionals that combines features of minimal change semantics and information semantics. As in information semantics, conditionals are interpreted relative to an information state in accordance with the Ramsey test idea: “if p then q” is supported at a state s iff q is supported at the hypothetical state s[p] obtained by restricting s to the p-worlds. However, information states are not modeled as simple sets of worlds, but by means of a (...) Lewisian system of spheres. Worlds in the inner sphere are considered possible; worlds outside of it are ruled out, but to different degrees. In this way, even when a state supports “not p”, it is still possible to suppose p consistently. I argue that this account does better than its predecessors with respect to a set of desiderata concerning inferences with conditionals. In particular, it captures three important facts: that a conditional is logically independent from its antecedent; that a sequence of antecedents behaves like a single conjunctive antecedent ; and that conditionals restrict the quantification domain of epistemic modals. I also discuss two ways to construe the role of a premise, and propose a generalized notion of entailment that keeps the two apart. (shrink)

We argue that Russell’s treatment of propositions containing non-existent denotations is the prelude of a strategy for discerning the predictive content of any proposition with descriptions (and incomplete symbols), insofar as its indeterminacy is classifiable as a possible extension. We argue, further, that Russell’s theory of propositional functions is dedicated to explaining the discernibility of hypothetical propositions, through representing (what we call) the superextension of assertoric modal propositions. The indeterminacy of the truth of hypothetical propositions is thus paired (...) with a second- order classification condition, expressing its conjectural content as the projected scope of instantiation of a propositional function; which in turn is the superextension of a modal predicate. Russell’s theory is his non-pragmatic answer to the problem of assertability in unstable and uncertain conditions. It involves a sophisticated thesis about the discernibility of complex contents, such as those represented by analogical and approximate denotations (descriptions, fictions, etc.), which classify more than one possibility of instantiation in different modal and intensional contexts. We will conclude this article by testing the assumption that Russell’s theory favors a coherentist theory, seeing that as it admits assertability conditions that are super-mapped in a system, or that derive from different orders of referential layers. (shrink)

Michael Fara's ‘habitual analysis’ of disposition ascriptions is equivalent to a kind of ceteris paribus conditional analysis which has no evident advantage over Martin's well known and simpler analysis. I describe an unsatisfactory hypothetical response to Martin's challenge, which is lacking in just the same respect as the analysis considered by Martin; Fara's habitual analysis is equivalent to this hypothetical analysis. The feature of the habitual analysis that is responsible for this cannot be harmlessly excised, for the resulting (...) analysis would be subject to familiar counter-examples. (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)

Philosophers and logicians have long debated how best to understand conditional or hypothetical sentences. William G. Lycan has a distinctive approach to this debate, attending not just to the semantics of such sentences, but equally to their syntax. He shows how insights from linguistic theory help to illuminate problems about the meaning and function of conditionals. For instance, philosophers and logicians have had problems analysing the locutions 'only if', 'unless', and 'even if'. Lycan sets out a general semantic (...) theory of conditionals which works for all such sentences; he assigns meanings to them in a way that explains how and why those meanings depend upon features of utterance context. According to Lycan's theory the 'if'-clauses refer to items called 'events', 'circumstances', or 'conditions'.Real Conditionals gives at last the definitive presentation of this original approach to a topic at the intersection of philosophy, logic, and linguistics. Lycan's characteristically lively and witty expository style ensures that it can be enjoyed by readers from all three disciplines. (shrink)

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

Although we are still in the dark when it comes to giving necessary and jointly sufficient criteria for what it takes to be thinking a singular thought, the paradigm cases are just ones where an agent is thinking about some particular object. When we erroneously think that Vulcan is a planet, our thought appears to be singular since it is, after all, about Vulcan. A promising way to explain this is to claim that there is something, a merely hypothetical (...) entity, that is Vulcan. There have been notable supporters for positing hypothetical entities for some time now, but the account of how we create hypothetical entities is still underdeveloped. In fact, we face a puzzle if we assume: hypothetical entities are created by us; we create a given hypothetical entity only when we falsely hypothesize something to be the unique F; we create the hypothetical entity long before we learn that there is no unique F. How can we possibly manage to conditionally and unknowingly create some entity when there is no unique F? In showing how this is possible, it will become clear that we have good reason for preferring a view that posits hypothetical entities over the alternative ways of accounting for our apparently singular thoughts about Vulcan, Pegasus, the Fountain of Youth, and so on. (shrink)

This article is about conditionalized modal statements whose antecedents concern a preferential attitude of an agent. The focus is on anankastic conditionals or, as they are known in the philosophical literature, hypothetical imperatives. We present a linguistically-motivated analysis of anankastic and related conditionals and use it to address challenges for semantic theories of natural language conditionals motivated by certain philosophical concerns about practical reasoning and the requirements of rationality.

The main aim of this paper is to study the notion of conditional right by means of constructive type theory (CTT) which provides the means to develop a system of contentual inferences rather than of syntactic derivations. Moreover, in line with Armgardt, we will first study the general notion of dependence as triggered by hypotheticals and then the logical structure of dependence specific to conditional right. I will develop this idea in a dialogical framework where the distinction between play-object and (...) strategy-object leads to the further distinction between two basic kinds of pieces of evidence and where meanings is constituted by the interaction of obligations and entitlements. The present paper is based on Rahman (2015). However, though the underlying CTT-analysis is the same, the dialogical reconstruction makes use of a new way of linking dialogical logic and CTT. Introduction. (shrink)

The hypothetical approach to the supersensible developed by Kant in his three Critiques, exemplified by his analysis of the aesthetic and reflective judgment in his third Critique, with their principle fortuitous purposiveness, can be considered as the basis for a new foundation of metaphysics. According to Kant’s limitation of cognition to the realm of sense intuition, theoretical knowledge of God, the subject, things-in-themselves, transcendental ideas is impossible. This leads to a kind of “negative theology” of the highest principle and (...) the supersensible as a whole. The reasons are rooted in the character of propositional thought, which can only circumscribe a singular, supersensible reality by means of predicative sentences and discursive thought. Taking Kant’s lead, but in contrast to his terminology, I call really existent singularities, including the thinking, knowing, desiring, feeling unique individuals we know as human beings, spontaneities, in order to distinguish them from descriptive characteristics attributed to them by predicative thought. Kant’s “practico-dogmatic” account of the postulates of God and immortality of the soul, based on the “fact of freedom” and its connection to the moral imperative, ensure the possibility of the “highest good” as final aim of moral behaviour — but cannot satisfy our need for knowledge of the supersensible. To “lay the groundwork” for experience of our own self-conscious reality, the reality of others like ourselves, of things which transcend the boundaries of sense intuition, and of true reciprocity, a different method is needed, one which leads us “beyond being and thought” to the unconditional beginning of conditional reality. (shrink)

Language theorists have recently come to have an increasing appreciation for the fact that context contributes heavily in determining our interpretation of what is said. Indeed, it now seems clear that no complete understanding of a natural language is possible without some account of the way in which context affects our interpretation of discourse. In this paper, I will attempt to explore one facet of the language – context relationship, namely, the relation between conditionals and context. The first part (...) of the paper develops an account of truth for conditionals which allows them to depend on momentary features of the context in which they are uttered. In the second half of the paper, comparisons with other recent theories of the conditional will be considered. Particular attention will be given to the problem of whether the conditional really violates classical inferences such as Hypothetical Syllogism and Contraposition as has often been claimed in recent years. (shrink)

The Independence postulate links current preferences between called-off acts with current preferences between constant acts. Under the assumption that the chance-events used in compound von Neumann-Morgenstern lotteries are value-neutral, current preferences between these constant acts are linked to current preferences between hypothetical acts, conditioned by those chance events. Under an assumption of stability of preferences over time, current preferences between these hypothetical acts are linked to future preferences between what are then and there constant acts. Here, I show (...) that a failure of Independence with respect to current preferences leads to an inconsistency in sequential decisions. Two called-off acts are constructed such that each is admissible in the same sequential decision and yet one is strictly preferred to the other. This responds to a question regarding admissibility posed by Rabinowicz ([2000] Preference stability and substitution of indifferents: A rejoinder to Seidenfeld, Theory and Decision 48: 311–318 [this issue]). (shrink)

This paper urges the importance of including conditional proof as an inference rule in the teaching of elementary symbolic logic. The paper explains how to make clear to students that conditional proof is valid. This is done by a little proof that shows that hypothetical syllogism (or the chain rule) is both intuitively valid yet redundant. Teaching conditional proof not only aids in a deeper understanding of the meaning of “if” but also provides a strong reminder to the student (...) that they have not proved that the conclusion is true but instead have shown that the conclusion follows from the premises. (shrink)

Possible worlds semantics for conditionals leave open the problem of how to construct models for realistic domains. In this paper, we show how to adapt logics of action and change such as John McCarthy’s Situation Calculus to conditional logics. We illustrate the idea by presenting models for conditionals whose antecedents combine a declarative condition with a hypothetical action.

This paper aims to show that Sosa’s theory of knowledge based on safety condition can provide a convincing response to the problem of philosophical skepticism. With regard to that, it is divided in three sections. The first section is dedicated to presenting the form of skeptical argument and few options we encounter when skeptic rises the challenge in the form of the so-called radical alternatives. The second section consists of the presentation of Sosa’s theory and safety condition, as well as (...) its differences and similarities with Nozick’s sensitivity condition and Dretske’s condition of conclusive reason. Finally, the third section evaluates Sosa’s theory in the light of Comesana’s counterexample. After the careful analysis of the hypothetical situation, it is shown that Comesana overlooks one important moment when he fixes the initial set of circumstances, which allows a successful defense of Sosa’s analysis of knowledge and safety condition. (shrink)

In his interesting paper, Duca argues that even though people don't apply a logical rule of inference – contraposition- when they try to solve the Wason task, they may be using another kind of formal strategy in terms of probabilistic relations between the antecedent and the consequent. It is suggested that there are two ways of intepreting this task – one logical and apriori, the other hypothetical and data driven. Taking a probabilistic interpretation of the conditional rule for subjects' (...) card selections in the Wason task seems much more justified in this second reading. If this is true, new questions arise: how does a subject recognize which method is contextually appropriate, and what makes a solution contextually rational? (shrink)