ABSTRACTTreating conditionals as probabilistic statements has been referred to as a defining feature of the “new paradigm” in cognitive psychology. Doing so is attractive for several reasons, but it complicates the problem of assessing the merits of conditional arguments. We consider several variables that relate to judging the persuasiveness of conditional arguments with uncertain premises. We also explore ways of judging the consistency of people's beliefs as represented by components of conditional arguments. Experimental results provide evidence that inconsistencies in (...) beliefs are more prevalent if the arguments’ components are spatially and temporally dispersed than if they are contiguous in space and time. This supports the idea that assuring the consistency among even a small number of beliefs is difficult to do, especially if the beliefs in question are not brought into consciousness at the same time; but consistency can be enhanced when beliefs are considered simultaneously or nea... (shrink)

This study examined the hypothesis that a key process in conditional reasoning with concrete premises involves on-line retrieval of information about potential alternate antecedents. Participants were asked to solve reasoning problems with causal conditional premises (If cause P then effect Q). These premises were inserted into short contexts. The availability of potential alternatives was varied from one context to another by adding statements that explicitly invalidated one or more of these alternatives (i.e., other causes that lead to the effect Q). (...) The invalidated alternatives differed in the degree of their semantic association to the consequent term (Q). The results show that the effect of invalidating one or more potential alternatives on the two uncertain logical forms, AC and DA, was largely determined by their relative associative strength. These results strongly support a model for conditional reasoning with causal premises that supposes that a key element in responding to the uncertain logical forms is on-line retrieval of at least one potential alternative antecedent. (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.

Informal logicians recognise the frequent use of unstated assumptions; some also recognise entertained arguments and recommend a suppositional approach 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.

Straipsnyje kritikuojamas 68-ame „Problemø“ numeryje skelbtas J. Èiurlionio teiginys, kad matematiniai Zenono Elëjieèio aporijos sprendimai „remiasi klaidinga implikacine prielaida“. Pirma, logikosdësniai nedraudþia ið klaidingø teiginiø pagrástai iðvesti teisingus teiginius, todël prielaidos klaidingumas neuþtikrina iðvados klaidingumo. Antra, minimos implikacijos antecedento loginæ reikðmæ lemiaempirinis faktas, todël net jei implikacijos konsekventas bûtinai klaidingas, implikacija yra loginiupoþiûriu atsitiktinë. Treèia, implikacijos konsekventas gali bûti interpretuojamas dvejopai. Viena interpretacija padaro já nomologiðkai bûtinai klaidingà, bet nerelevantiðkà Zenono aporijai; kita interpretacija padaro teiginá relevantiðkà, bet nebûtinai klaidingà. Taigi (...) nëra jokio pagrindo manyti, kad implikacinë prielaida, kuria, Èiulionio teigimu, remiasi matematiniai Zenono Elëjieèio aporijos sprendimai, yra klaidinga.Pagrindiniai þodþiai: Achilo ir vëþlio aporija, tapatumo sàlygos, aporijø sprendimai. (shrink)

Some studies have reported that, under some circumstances, participants sometimes reject the truth of conditional premises and give incorrect uncertain conclusions to MP and MT, despite the standard instructions to assume the truth of the premises. Instructions that emphasise the logical nature of the task, on the other hand, increase the number of valid conclusions to these two inferences. In this paper, we examine two possible explanations for the influence of instructions on the production of valid conclusions: (1) instructions trigger (...) a logical mode of thinking that is appropriate for the task to be solved, and (2) instructions affect the way that retrieved information is used when constructing a mental representation of the premises. In order to compare these two hypothesis, we used conditional causal relations having either many or few disabling conditions (i.e. cases of P and not-Q) and presented them in four different instructional conditions. When presented with the standard instructions to suppose the premises to be true, MP and MT inferences show a relatively low percentage of valid conclusions. However, when the logical nature of the task and the necessity to assume the truth of the premises are emphasised, the number of valid conclusions greatly increases. Also, if disabling conditions are made explicit or generated before the presentation of these logical instructions, the performance on MP and MT is lower than when only the logical instructions are presented. Finally, the instructions had no effect on AC and DA. From these results, we concluded that the instructions had an effect on the use of retrieved information rather than on inducing different modes of thinking. (shrink)

Mental model theory has been used to explain many differing phenomena in adult reasoning, including the extensively studied case of conditional reasoning. However, the current theory makes predictions about the development of conditional reasoning that are not consistent with data. In this article, young children's performance on conditional reasoning problems and the justifications given are analysed. A mental model account of conditional reasoning is proposed that assumes that (1) young children can reason with two models and (2) the fleshing out (...) of conditionals involves activation of information in semantic memory that uses the minor premise as a retrieval cue. (shrink)

Is truth a condition of premise adequacy? We may distinguish objective and subjective argument correctness. Objective correctness means true premises rendering the conclusion true or probable. Subjective correctness means acceptable pr emises rendering the conclusion acceptable. Acceptability depends on evidence available and so is internalist. Objective and subjective correctness of the premises is ordinarily distinct. For connection adequacy, objective rightness and subjective righ tness coincide. We recognize entailment or rendering probably a priori. Logic is thus internalist. Logic needs an (...) internalist notion of acceptability for premise evaluation to fall within its purview, although it need not deny the objective sens e of rightness. (shrink)

The rise of causality and the attendant graph-theoretic modeling tools in the study of counterfactual reasoning has had resounding effects in many areas of cognitive science, but it has thus far not permeated the mainstream in linguistic theory to a comparable degree. In this study I show that a version of the predominant framework for the formal semantic analysis of conditionals, Kratzer-style premise semantics, allows for a straightforward implementation of the crucial ideas and insights of Pearl-style causal networks. (...) I spell out the details of such an implementation, focusing especially on the notions of intervention on a network and backtracking interpretations of counterfactuals. (shrink)

Expressing a widely-held view, David Hitchcock claims that "an enthymematic argument ... assumes at least the truth of the argument's associated conditional ... whose antecedent is the conjunction of the argument's explicit premises and whose consequent is the argument's conclusion." But even definitionally, this view is problematic, since an argument's being "enthymematic" or incomplete with respect to its explicit premises means that the conclusion is not implied by these premises alone. The paper attempts to specify the ways in which the (...) view is incorrect, as well as seemingly correct (e.g., the case of a Modus Ponens wherein the major premise is implicit). -/- . (shrink)

Oaksford & Chater (O&C) begin in the halfway Bayesian house of assuming that minor premises in conditional inferences are certain. We demonstrate that this assumption is a serious limitation. They additionally suggest that appealing to Jeffrey's rule could make their approach more general. We present evidence that this rule is not limited enough to account for actual probability judgements.

The paper focuses on the difference between event‐conditionals and premise‐conditionals. An event‐conditional contributes to event structure: it modifies the main clause event; a premise‐conditional structures the discourse: it makes manifest a proposition that is the privileged context for the processing of the associated clause. The two types of conditional clauses will be shown to differ both in terms of their ‘external syntax’ and in terms of their ‘internal syntax’. The peripheral structure of event conditionals will (...) be shown to lack the functional head Force, which encodes illocutionary force. Event conditionals are merged inside the IP of the matrix clause. Premise‐conditionals contain the head Force and they are merged outside the associated CP. (shrink)

Contemporary research in the field of Foucauldian studies on education have pointed to a growing imbrication between educational practises and neoliberal ideas. The problematization of such scenario would lead to two premises, grounded on a general hypothesis for the analysis of the educational present. The first premise: nowadays, the educational or, to be more precise, educationalizing practises—since they would not deal only with the schooling effort, but also with the diffusion of a great number of pedagogical initiatives of non-formal (...) character—consists in an efficient rationality of governing of oneself and others. The second premise is that such educationalizing movement consists not only in the expression but also in the typical modus operandi of the current governmentalization processes, which aim at a large-scale administration of the multiplicity of populations now in terms of a lifelong educatibility for the citizens. These two premises sustain the hypothesis that the present educational practises do not restrict themselves to the mere condition of reiterative apparatus of imperatives extrinsic to them, but have in fact cemented themselves as a generative locus of the veridiction/subjectivization games capable of overrunning the whole social space. (shrink)

Modus ponens is the argument from premises of the form If A, then B and A to the conclusion B. Nearly all participants agree that the modus ponens conclusion logically follows when the argument appears in this Basic form. However, adding a further premise can lower participants’ rate of agreement—an effect called suppression. We propose a theory of suppression that draws on contemporary ideas about conditional sentences in linguistics and philosophy. Semantically, the theory assumes that people interpret an indicative (...) conditional as a context-sensitive strict conditional: true if and only if its consequent is true in each of a contextually determined set of situations in which its antecedent is true. Pragmatically, the theory claims that context changes in response to new assertions, including new conditional premises. Thus, the conclusion of a modus ponens argument may no longer be accepted in the changed context. Psychologically, the theory describes people as capable of reasoning about broad classes of possible situations, ordered by typicality, without having to reason about individual possible worlds. The theory accounts for the main suppression phenomena, and it generates some novel predictions that new experiments confirm. (shrink)

"If you turn left at the next corner, you will see a blue house at the end of the street." That sentence -- a conditional -- might be true even though it is possible that you will not see a blue house at the end of the street when you turn left at the next corner. A moving van may block your view; the house may have been painted pink; a crow might swoop down and peck out your eyes. Still, (...) in some contexts, we might ignore these possibilities and correctly assert the conditional. In this book, Christopher Gauker argues that such context-relativity is the key to understanding the semantics of conditionals. Contexts are defined as objective features of the situation in which a conversation takes place, and the semantic properties of sentences -- conditionals included -- are defined in terms of assertibility in a context. One of the primary goals of a theory of conditionals has to be to distinguish correctly between valid and invalid arguments containing conditionals. According to Gauker, an argument is valid if the conclusion is assertible in every context in which the premises are assertible. This runs counter to what Gauker sees as a systematic misreading of the data by other authors, who judge arguments to be invalid if they can think of a context in which the premises are judged true and some other context in which the conclusion is judged false. Different schools of thought on conditionals reflect fundamentally different approaches to semantics. Gauker offers his theory as a motive and test case for a distinctive kind of semantics that dispenses with reference relations and possible worlds. (shrink)

Acceptability is a thoroughly normative epistemic notion. If a statement is acceptable, i.e. it is proper to take it as a premise, then one is justified in accepting it. We also hold that a statement is acceptable just in case there is a presumption of warrant in its favor. We thus see acceptability connected to epistemic normativity on the one hand and to warrant on the other. But there is a distinct tension in this dual connection. The dominant tradition (...) in modern epistemology sees epistemic justification as an internalist notion. We are justified in holding a belief just in case certain conditions are fulfilled of which we have privileged access. Warrant is an externalist notion. We have no privileged access to the conditions of warrant. Is our understanding of acceptability as both normative and definable in terms of presumption of warrant philosophically coherent? We shall argue that it is a philosophically coherent notion. Presumption of warrant, unlike warrant, is an internalist notion. Our position can be characterized as an externalist internal ism. It avoids the charge brought against externalism of allowing one to be justified in accepting some claim even if one has no evidence for it. We meet the classical internalist challenge that acceptance is normatively proper only if one has done one's epistemic duty and thus one is aware of the normative propriety of the acceptance by providing a non-deontological definition of epistemic justification, and arguing that this is still a sufficiently normative notion for acceptability. (shrink)

We investigate how the perceived uncertainty of a conditional affects a person's choice of conclusion. We use a novel procedure to introduce uncertainty by manipulating the conditional probability of the consequent given the antecedent. In Experiment 1, we show first that subjects reduce their choice of valid conclusions when a conditional is followed by an additional premise that makes the major premise uncertain. In this we replicate Byrne. These subjects choose, instead, a qualified conclusion expressing uncertainty. If subjects (...) are given a third statement that qualifies the likelihood of the additional premise, then the uncertainty of the conclusions they choose is systematically related to the suggested uncertainty. Experiment 2 confirms these observations in problems that omit the additional premise and qualify the first premise directly. Experiment 3 shows that the qualifying statement also affects the perceived probability of the consequent given the antecedent of the conditional. Experiment 4 investigates the effect of suggested uncertainty on the fallacies and shows that increases in uncertainty reduce the number of certain conclusions that are chosen while affirming the consequent but have no effect on denying the antecedent. We discuss our results in terms of rule theories and mental models and conclude that the latter give the most natural account of our results. (shrink)

While there is now considerable experimental evidence that, on the one hand, participants assign to the indicative conditional as probability the conditional probability of consequent given antecedent and, on the other, they assign to the indicative conditional the “defective truth-table” in which a conditional with false antecedent is deemed neither true nor false, these findings do not in themselves establish which multi-premise inferences involving conditionals participants endorse. A natural extension of the truth-table semantics pronounces as valid numerous inference (...) patterns that do seem to be part of ordinary usage. However, coupled with something the probability account gives us—namely that when conditional-free ϕ entails conditional-free ψ, “if ϕ then ψ” is a trivial, uninformative truth—we have enough logic to derive the paradoxes of material implication. It thus becomes a matter of some urgency to determine which inference patterns involving indicative conditionals participants do endorse. Only thus will we be able to arrive at a realistic, systematic semantics for the indicative conditional. (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)

Previous studies have shown that 1 participants are reluctant to accept a conclusion as certainly true when it is derived from a valid conditional argument that includes a doubtful premise, and 2 participants typically link the degree of uncertainty found in a given premise set to its conclusion. Two experiments were designed to further investigate these phenomena. Ninety adult participants in Experiment 1 were first asked to judge the validity of three conditional arguments Modus Ponens, Denial of the (...) Antecedent, and Affirmation of the Consequent . They were then required to evaluate conclusion uncertainty as a function of two degrees of asserted uncertainty in the major conditional premise If p then it is very probable that q and if p then it is not very probable that q of the arguments from the first task that were otherwise unchanged. Results revealed an effect for asserted-uncertainty in two of the three argument forms. Marginal support was found for the hypothesis that perceived argument validity would be a predictor of performance. Experiment 2 investigated the way 40 adult participants combined two sources of asserted uncertainty, one in the major premise and another in the minor premise, when they had to score the uncertainty of the conclusion. The two most prominent kinds of responses were to choose the same likelihood as the weaker of the two expressed in the premises, or a lower one. However, the within-subject consistency was poor. Theoretical implications are discussed. (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)

This paper investigates what happens when we merge two different lines of theorizing about counterfactuals. One is the comparative closeness view, which was developed by Stalnaker and Lewis in the framework of possible worlds semantics. The second is the interventionist view, which is part of the causal models framework developed in statistics and computer science. Common lore and existing literature have it that the two views can be easily fit together, aside from a few details. I argue that, on the (...) contrary, transplanting causal-models-inspired ideas in a possible worlds framework yields a new semantics. The difference is grounded in different algorithms for handling inconsistent information, hence it touches on issues that are at the very heart of a semantics for contrary-to-fact conditionals. Roughly, Stalnaker/Lewis semantics requires us to evaluate the consequent of a counterfactual at all closest antecedent-verifying possibilities. Causal-models-based semantics also does this, but in addition uses the information contained in the antecedent, together with background causal information, to shift what worlds count as closest. This makes systematically different predictions and generates a new logic. The upshot is that we have a new semantics to study, and a substantial theoretical choice to make. (shrink)

Quentin Smith has argued that the new tenseless theory of time is faced with insurmountable problems and should be abandoned in favour of the tensed theory of time. Smith;s main argument attacks the fundamental premise of the tenseless theory: that tenseless truth conditions for tokens of tensed sentences adequately capture the meaning of tensed sentences. His position is that tenseless truth conditions cannot explain the logical relations between tensed sentences, thus the tensed theory must be accepted. Against Smith, this (...) paper adopts an alternative approach to the explanation of the entailment relations between sentences which contain indexicals. The approach drops the reliance upon tokens and instead relies on the evaluation of sentence types with respect to a context rather than upon actual or possible utterances of tokens of the types. This (new) version of the tenseless theory of time can adequately explain the relevant entailment relations between tensed sentences. (shrink)

This paper explores an idea of Stoic descent that is largely neglected nowadays, the idea that an argument is valid when the conditional formed by the conjunction of its premises as antecedent and its conclusion as consequent is true. As it will be argued, once some basic features of our naıve understanding of validity are properly spelled out, and a suitable account of conditionals is adopted, the equivalence between valid arguments and true conditionals makes perfect sense. The account (...) of validity outlined here, which displays one coherent way to articulate the Stoic intuition, accords with standard formal treatments of deductive validity and encompasses an independently grounded characterization of inductive validity. (shrink)

This paper develops the idea that valid arguments are equivalent to true conditionals by combining Kripke’s theory of truth with the evidential account of conditionals offered by Crupi and Iacona. As will be shown, in a first-order language that contains a naïve truth predicate and a suitable conditional, one can define a validity predicate in accordance with the thesis that the inference from a conjunction of premises to a conclusion is valid when the corresponding conditional is true. The (...) validity predicate so defined significantly increases our expressive resources and provides a coherent formal treatment of paradoxical arguments. (shrink)

According to Paul Boghossian and others, inference is subject to the taking condition: it necessarily involves the thinker taking his premises to support his conclusion, and drawing the conclusion because of that fact. Boghossian argues that this condition vindicates the idea that inference is an expression of agency, and that it has several other important implications too. However, we argue in this paper that the taking condition should be rejected. The condition gives rise to several serious prima facie problems and (...) the reasons which have been offered in favour of it fail to convince. (shrink)

The standard use of the propositional calculus ('P.C.?) in analyzing the validity of inferences involving conditionals leads to fallacies, and the problem is to determine where P.C. may be ?safely? used. An alternative analysis of criteria of reasonableness of inferences in terms of conditions of justification rather than truth of statements is proposed. It is argued, under certain restrictions, that P. C. may be safely used, except in inferences whose conclusions are conditionals whose antecedents are incompatible with the (...) premises in the sense that if the antecedent became known, some of the previously asserted premises would have to be withdrawn. (shrink)

It has recently been argued that inference essentially involves the thinker taking his premises to support his conclusion and drawing his conclusion because of this fact. However, this Taking Condition has also been criticized: If taking is interpreted as believing, it seems to lead to a vicious regress and to overintellectualize the act of inferring. In this paper, I examine and reject various attempts to salvage the Taking Condition, either by interpreting inferring as a kind of rule-following, or by finding (...) an innocuous role for the taking-belief. Finally, I propose an alternative account of taking, according to which it is not a separate belief, but rather an aspect of the attitude of believing: Believing that p implies not only taking p to be true and taking oneself to believe that p, but also taking one's reasons q to support p, when the belief in question is held on account of an inference. (shrink)

We report two studies on the effect of implicitly versus explicitly conveying affirmation and denial problems about conditionals. Recently Evans and Handley (1999) and Schroyens et al. (1999b, 2000b) showed that implicit referencing elicits matching bias: Fewer determinate inferences are made, when the categorical premise (e.g., B) mismatches the conditional's referred clause (e.g., A). Also, the effect of implicit affirmation (B affirms not-A) is larger than the effect of implicit denial (B denies A). Schroyens et al. hypothesised that (...) this interaction is due to uncertainty in the case-wise affirmation of the contrast class of negated elements involved in implicit affirmations. In Experiment 1 we tested this hypothesis by manipulating the set size of the conditional clauses. The results confirm that binary sets, where the contrast class is a singleton, eliminate the differential effect of implicit affirmation and denial. With non-binary sets the interaction is not modulated by the scope of the contrast class (3, 5, 9 elements). Experiment 2 further investigated the role of contrast classes by using class inclusion to construct implicit affirmations (Mammal vs Mammal or Monkey) and implicit denial (No-Mammal vs Mammal or Monkey), in addition to the standard implicit problems mediated by contrast-class inclusion [(No-)Mammal/No-Mammal; Reptile; Snake). Findings indicate that class inclusion (Mammal/Monkey; Reptile/ Snake) only marginally affects performance, and is independent of the type of problem. This would suggest that the implicitness problem-type interaction is dependent on constructing contrast classes. However, the experiment failed to replicate the interaction, even on the subset of problems repeating the abstract letter/number format of Experiment 1. Moreover, with the natural binary set-sizes (vowels/consonants) the implicitness effect was eliminated entirely. (shrink)

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)

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 (...) class='Hi'>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)

Using Gärdenfors's notion of epistemic entrenchment, we develop the semantics of a logic which accounts for the following points. It explains why we may generally infer `If ~A then B´ if all we know is AvB while must not generally infer `If ~A then B´ if all we know is {AvB, A}. More generally, it explains the nonmonotonic nature of the consequence relation governing languages which contain conditionals, and it explains how we can deduce conditionals from premise (...) sets without conditionals. Depending on the language at hand, our logic provides different ways of keeping the Ramsey test and getting round the Gärdenfors triviality theorem. I argue that consistent additions of new items of belief are not to be performed by transitions to logical expansions. (shrink)

Three experiments are reported which show that in certain contexts subjects reject instances of the valid modus ponens and modus tollens inference form in conditional arguments. For example, when a conditional premise, such as: If she meets her friend then she will go to a play, is accompanied by a conditional containing an additional requirement: If she has enough money then she will go to a play, subjects reject the inference from the categorical premise: She meets her friend, (...) to the conclusion: She will go to a play. Other contexts suppress the conditional fallacies. The first experiment demonstrates the effects of context on conditional reasoning. The second experiment shows that the inference suppression disappears when the categorical premise refers to both of the antecedents, such as: She meets her friend and she has enough money. In this case, subjects make both the valid inferences and the fallacies, regardless of the contextual information. The third experiment establishes that when subjects are given general information about the duration of a situation in which a conditional inducement was uttered, such as: If you shout then I will shoot you, they reject both the valid inferences and the fallacies. The results suggest that the interpretation of premises plays an even more central role in reasoning than has previously been admitted. Trois expériences montrent que dans certains contextes les sujets rejettent des instances valides de modus ponens et de modus tollens dans des énoncés conditionnels. Par exemple, quand une prémisse conditionnelle comme: Si elle rencontre son ami, alors elle ira jouer, est accompagnée par une phrase contenant une condition supplémentaire: Si elle a assez d'argent, alors elle ira jouer, les sujets rejettent l'inférence liant la prémisse catégorielle: Elle rencontre son ami, à la conclusion: Elle ira jouer. D'autres contextes éliminent également les inférences conditionnelles fallacieuses. La premiére expérience démontre l'effet du contexte sur la raisonnement conditionnel. La deuxiéme expérience montre que la suppression de l'inférence disparait quand la prémisse catégorielle fait référence aux deux antécédants, comme: Elle rencontre son ami et elle a assez d'argent. Dans ce cas, les sujets font aussi bien les inférences valides et fallacieuses, quelle que soit l'information contextuelle. La troisiéme expérience établit que quand l'on donne aux sujets des informations générales à propos de la durée d'une situation dans laquelle une conditionnelle a été prononcée, comme Si tu cries, alors je te tire dessus, ils rejettent autant les inférences valides que les inférences fallacieuses. Ces résultats suggèrent que l'interprétation des prémisses joue un rŏle encore plus central dans le raisonnement que l'on admettait auparavant. (shrink)

This paper reviews the psychological investigation of reasoning with conditionals, putting an emphasis on recent work. In the first part, a few methodological remarks are presented. In the second part, the main theories of deductive reasoning (mental rules, mental models, and the probabilistic approach) are considered in turn; their content is summarised and the semantics they assume for if and the way they explain formal conditional reasoning are discussed, in particular in the light of experimental work on the probability (...) of conditionals. The last part presents the recent shift of interest towards the study of conditional reasoning in context, that is, with large knowledge bases and uncertain premises. (shrink)

This paper deals with the truth conditions of conditional sentences. It focuses on a particular class of problematic examples for semantic theories for these sentences. I will argue that the examples show the need to refer to dynamic, in particular causal laws in an approach to their truth conditions. More particularly, I will claim that we need a causal notion of consequence. The proposal subsequently made uses a representation of causal dependencies as proposed in Pearl (2000) to formalize a causal (...) notion of consequence. This notion inserted in premise semantics for counterfactuals in the style of Veltman (1976) and Kratzer (1979) will provide a new interpretation rule for conditionals. I will illustrate how this approach overcomes problems of previous proposals and end with some remarks on remaining questions. (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)

A total of 152 students were asked to respond to a series of causal conditional (“If P then Q”) inferences with major premises for which there was variable access to information contradicting the premises. Half the students were given 12.5 s for each inference, the other half were given 8.5 s. The percentage of accepted inferences was significantly lower when the time was shorter for the MP and MT inferences, but no effect was observed for the AC and DA inferences. (...) Results are interpreted as supporting the idea that inhibition of retrieved information contradicting the premise is necessary to explain reasoning with the MP and MT inferences under logical instructions (Markovits & Barrouillet, 2002). (shrink)

In this paper I outline an argument for the existence of God. This argument suggests that, if an all-good supernatural agent were to exist, such as the God of Theism, then He could not perform an immoral act. From this premise alone a formal proof for the existence of God can be derived. Perhaps unsurprisingly, when this argument is examined closely it is revealed to be fallacious. However, what we find is that the fallacy involves a special type of (...) equivocation; one that illustrates the difference between non-truth-functional subjunctive conditionals and truth-functional material conditionals. (shrink)

Based on an original interpretation of the core concepts in Nietzsche’s thought, and on their subsequent overcoming, this book embodies a radically new perspective that in essence reconsiders, upon grounded ontological premises and revealed anthropological evidences, both the notions of human and superhuman as still bound to a prevailing standpoint of impotence and limitation. The chief themes of metaphysics, from being to becoming, from entity to identity are all dealt with in the leading terms of the category power and of (...) its dialectical self-negation to inhere in parallel within a far more extended view of the human respecting a dualist assumption and the unfathomable spatio-temporal vastness of the Real in which the phase of man is but infinitesimal. It is supported by more than 500 notes and a glossary with more than 60 key terms, each carefully explained. References are contained to authors spanning millennia and in several fields of knowledge. Narrative suggestions are also included, serving as an aid to the comprehension of the exposition to follow in compliance with the underlying mythical aspect of the argument. A challenge to existing concepts, this book introduces the reader to the actual existence of a human reality which exceeds the hitherto known and considered from whatever point of view and which has remained latent and indistinct under the form of myths, from the dawn of history until nowadays mass media culture as a need of power in an intrinsically powerless human world. Revealed in its necessary function of actual presence antithetical to the limitedness of man, and referred accordingly to the comprehensive meaning of power, this condition radically opposes any limitation thus far ascribed to the human. (shrink)

What is involved in making an inference? This chapter argues against what Paul Boghossian calls the Taking Condition: "Inferring necessarily involves the thinker taking his premises to support his conclusion and drawing his conclusion because of that fact" (2014: 5). I won’t argue that the Taking Condition is incoherent: that nothing can coherently play the role that takings are supposed to play in inference. Instead, I’ll argue that it cannot plausibly explain all the inferential knowledge that we ordinarily take ourselves (...) to have. Moreover, I’ll argue that we don’t need it to understand the nature of inference. (shrink)

The two main psychological theories of the ordinary conditional were designed to account for inferences made from assumptions, but few premises in everyday life can be simply assumed true. Useful premises usually have a probability that is less than certainty. But what is the probability of the ordinary conditional and how is it determined? We argue that people use a two stage Ramsey test that we specify to make probability judgements about indicative conditionals in natural language, and we describe (...) experiments that support this conclusion. Our account can explain why most people give the conditional probability as the probability of the conditional, but also why some give the conjunctive probability. We discuss how our psychological work is related to the analysis of ordinary indicative conditionals in philosophical logic. (shrink)

An important field of probability logic is the investigation of inference rules that propagate point probabilities or, more generally, interval probabilities from premises to conclusions. Conditional probability logic (CPL) interprets the common sense expressions of the form “if . . . , then . . . ” by conditional probabilities and not by the probability of the material implication. An inference rule is probabilistically informative if the coherent probability interval of its conclusion is not necessarily equal to the unit interval (...) [0, 1]. Not all logically valid inference rules are probabilistically informative and vice versa. The relationship between logically valid and probabilistically informative inference rules is discussed and illustrated by examples such as the modus ponens or the affirming the consequent. We propose a method to evaluate the strength of CPL inference. (shrink)

The relativistic revolution led to varieties of neo-Kantianism in which constitutive principles define the object of scientific knowledge in a domain-dependent and historically mutable manner. These principles are a priori insofar as they are necessary premises for the formulation of empirical laws in a given domain, but they lack the self-evidence of Kant’s a priori and they cannot be identified without prior knowledge of the theory they purport to frame. In contrast, the rationalist endeavors of a few masters of theoretical (...) physics have led to comprehensibility conditions that are easily admitted in a given domain and yet suffice to generate the theory of this domain. The purpose of this essay is to compare these two kinds of relativized a priori, to discuss the nature of the comprehensibility conditions, and to demonstrate their effectiveness in a modular conception of physical theories. (shrink)

Reasoning with conditionals is often thought to be non-monotonic, but there is no incompatibility with classical logic, and no need to formalise inference itself as probabilistic. When the addition of a new premise leads to abandonment of a previously compelling conclusion reached by modus ponens, for example, this is generally because it is hard to think of a model in which the conditional and the new premise are true.

PREFACE PART I METAPHYSICS Review of John McDowell’s Mind and World Special Sciences: Still Autonomous after All These Years Conclusion Acknowledgment Notes PART II CONCEPTS Review of Christopher Peacocke’s A Study of Concepts Notes There Are No Recognitional Concepts--Not Even RED Introduction Compositionality Why Premise P is Plausible Objections Conclusion Afterword Acknowledgment Notes There Are No Recognitional Concepts--Not Even RED, Part 2: The Plot Thickens Introduction: The Story ’til Now Compositonality and Learnability Notes Do We Think in Mentalese? Remarks (...) on Some Arguments of Peter Carruthers Appendix: Higher-Order Thoughts Notes Review of A. W. Moore’s Points of View PART III COGNITIVE ARCHITECTURE Review of Paul Churchland’s The Engine of Reason, The Seat of the Soul Connectionism and the Problem of Systematicity: Why Smolensky’s Solution Doesn’t Work Introduction I The Systematicity Problem and Its Classical Solution II Weak Compositionality III Strong Compositional Structure Conclusion Notes Connectionism and the Problem of Systematicity : Why Smolensky’s Solution Still Doesn’t Work Stage 1: Classical Theories The Connection with The Connection with Stage 2: Smolenksy Architectures Stage 3: Why Smolensky’s Solution Still Doesn’t Work Digression on singing and sailing Acknowledgment Notes There and Back Again: A Review of Annette Karmiloff-Smith’s Beyond Modularity 1. Encapsulation 2. Inaccessibility 3. Domain specificity 4. Innateness Conclusion Notes Review of Jeff Elman et al., Rethinking Innateness Brainlikeness Interactions Representational Nativism Empiricism Review of Steven Mithen’s The Prehistory of the Mind PART IV PHILOSOPHICAL DARWINISM Review of Richard Dawkins’s Climbing Mount Improbable Deconstructing Dennett’s Darwin Introduction Adaptation Adaptation and Teleology Deconstruction Notes Is Science Biologically Possible? Comments on Some Arguments of Patricia Churchland and of Alvin Plantinga Acknowledgment Notes Review of Steven Pinker’s How the Mind Works and Henry Plotkin’s Evolution in Mind Computation Massive modularity Innateness Psychological Darwinism. (shrink)