2,048 research outputs found

    A Counterexample to Modus Ponenses

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    McGee argued that modus ponens was invalid for the natural language conditional ‘If
then
’. Many subsequent responses have argued that, while McGee’s examples show that modus ponens fails to preserve truth, they do not show that modus ponens fails to preserve rational full acceptance, and thus modus ponens may still be valid in the latter informational sense. I show that when we turn our attention from indicative conditionals to subjunctive conditionals, we find that modus ponens does not preserve either truth or rational full acceptance, and thus is not valid in either sense. In concluding I briefly consider how we can account for these facts

    Isolating Correct Reasoning

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    This paper tries to do three things. First, it tries to make it plausible that correct rules of reasoning do not always preserve justification: in other words, if you begin with a justified attitude, and reason correctly from that premise, it can nevertheless happen that you’ll nevertheless arrive at an unjustified attitude. Attempts to show that such cases in fact involve following an incorrect rule of reasoning cannot be vindicated. Second, it also argues that correct rules of reasoning do not even correspond to permissions of “structural rationality”: it is not always structurally permissible to base an attitude on other attitudes from which it follows by correct reasoning. Third, from these observations it tries to build a somewhat positive account of the correctness of rules of reasoning as a more sui generis notion irreducible to either justification or structural rationality. This account vindicates an important unity of theoretical and practical reasoning as well as a qualified version of the thesis that deductive logic supplies correct rules of reasoning

    "If-then" as a version of "Implies"

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    Russell’s role in the controversy about the paradoxes of material implication is usually presented as a tale of how even the greatest minds can fall prey of basic conceptual confusions. Quine accused him of making a silly mistake in Principia Mathematica. He interpreted “if- then” as a version of “implies” and called it material implication. Quine’s accusation is that this decision involved a use-mention fallacy because the antecedent and consequent of “if- then” are used instead of being mentioned as the premise and the conclusion of an implication relation. It was his opinion that the criticisms and alternatives to the material implication presented by C. I. Lewis and others would never be made in the first place if Russell simply called the Philonian construction “material conditional” instead of “material implication”. Quine’s interpretation on the topic became hugely influential, if not universally accepted. This paper will present the following criticisms against this interpretation: (1) the notion of material implication does not involve a use-mention fallacy, since the components of “if-then” are mentioned and not used; (2) Quine’s belief that the components of “if-then” are used was motivated by a conditional-assertion view of conditionals that is widely controversial and faces numerous difficulties; (3) if anything, it was Quine who could be accused of fallacious reasoning: he ignored that in the assertion of a conditional is the whole proposition that is asserted and not its constituents; (4) the Philonian construction remains counter-intuitive even if it is called “material conditional”; (5) the Philonian construction is more plausible when it is interpreted as a material implication

    Recapture, Transparency, Negation and a Logic for the CatuáčŁkoáč­i

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    The recent literature on Nāgārjuna’s catuáčŁkoáč­i centres around Jay Garfield’s (2009) and Graham Priest’s (2010) interpretation. It is an open discussion to what extent their interpretation is an adequate model of the logic for the catuskoti, and the Mūla-madhyamaka-kārikā. Priest and Garfield try to make sense of the contradictions within the catuskoti by appeal to a series of lattices – orderings of truth-values, supposed to model the path to enlightenment. They use Anderson & Belnaps\u27s (1975) framework of First Degree Entailment. Cotnoir (2015) has argued that the lattices of Priest and Garfield cannot ground the logic of the catuskoti. The concern is simple: on the one hand, FDE brings with it the failure of classical principles such as modus ponens. On the other hand, we frequently encounter Nāgārjuna using classical principles in other arguments in the MMK. There is a problem of validity. If FDE is Nāgārjuna’s logic of choice, he is facing what is commonly called the classical recapture problem: how to make sense of cases where classical principles like modus pones are valid? One cannot just add principles like modus pones as assumptions, because in the background paraconsistent logic this does not rule out their negations. In this essay, I shall explore and critically evaluate Cotnoir’s proposal. In detail, I shall reveal that his framework suffers collapse of the kotis. Taking Cotnoir’s concerns seriously, I shall suggest a formulation of the catuskoti in classical Boolean Algebra, extended by the notion of an external negation as an illocutionary act. I will focus on purely formal considerations, leaving doctrinal matters to the scholarly discourse – as far as this is possible

    On Stalnaker's "Indicative Conditionals"

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    This paper is a guide to the main ideas and innovations in Robert Stalnaker's "Indicative Conditionals". The paper is for a volume of essays on twenty-one classics of formal semantics edited by Louise McNally and ZoltĂ n Gendler Szab

    Recapture, Transparency, Negation and a Logic for the Catuskoti

    Get PDF
    The recent literature on Nāgārjuna’s catuáčŁkoáč­i centres around Jay Garfield’s (2009) and Graham Priest’s (2010) interpretation. It is an open discussion to what extent their interpretation is an adequate model of the logic for the catuskoti, and the MĆ«la-madhyamaka-kārikā. Priest and Garfield try to make sense of the contradictions within the catuskoti by appeal to a series of lattices – orderings of truth-values, supposed to model the path to enlightenment. They use Anderson & Belnaps's (1975) framework of First Degree Entailment. Cotnoir (2015) has argued that the lattices of Priest and Garfield cannot ground the logic of the catuskoti. The concern is simple: on the one hand, FDE brings with it the failure of classical principles such as modus ponens. On the other hand, we frequently encounter Nāgārjuna using classical principles in other arguments in the MMK. There is a problem of validity. If FDE is Nāgārjuna’s logic of choice, he is facing what is commonly called the classical recapture problem: how to make sense of cases where classical principles like modus pones are valid? One cannot just add principles like modus ponens as assumptions, because in the background paraconsistent logic this does not rule out their negations. In this essay, I shall explore and critically evaluate Cotnoir’s proposal. In detail, I shall reveal that his framework suffers collapse of the kotis. Furthermore, I shall argue that the Collapse Argument has been misguided from the outset. The last chapter suggests a formulation of the catuskoti in classical Boolean Algebra, extended by the notion of an external negation as an illocutionary act. I will focus on purely formal considerations, leaving doctrinal matters to the scholarly discourse – as far as this is possible

    Boghossian's template and transmission failure

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    Within his overarching program aiming to defend an epistemic conception of analyticity, Boghossian (1996 and 1997) has offered a clear-cut explanation of how we can acquire a priori knowledge of logical truths and logical rules through implicit definition. The explanation is based on a special template or general form of argument. Ebert (2005) has argued that an enhanced version of this template is flawed because a segment of it is unable to transmit warrant from its premises to the conclusion. This article aims to defend the template from this objection. We provide an accurate description of the type of non-transmissivity that Ebert attributes to the template and clarify why this is a novel type of non-transmissivity. Then, we argue that Jenkins (2008)’s response to Ebert fails because it focuses on doxastic rather than propositional warrant. Finally, we rebut Ebert’s objection on Boghossian’s behalf by showing that it rests on an unwarranted assumption and is internally incoherent

    A 4-valued logic of strong conditional

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    How to say no less, no more about conditional than what is needed? From a logical analysis of necessary and sufficient conditions (Section 1), we argue that a stronger account of conditional can be obtained in two steps: firstly, by reminding its historical roots inside modal logic and set-theory (Section 2); secondly, by revising the meaning of logical values, thereby getting rid of the paradoxes of material implication whilst showing the bivalent roots of conditional as a speech-act based on affirmations and rejections (Section 3). Finally, the two main inference rules for conditional, viz. Modus Ponens and Modus Tollens, are reassessed through a broader definition of logical consequence that encompasses both a normal relation of truth propagation and a weaker relation of falsity non-propagation from premises to conclusion (Section 3)
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