Consider this situation: Here are two envelopes. You have one of them. Each envelope contains some quantity of money, which can be of any positive real magnitude. One contains twice the amount of money that the other contains, but you do not know which one. You can keep the money in your envelope, whose numerical value you do not know at this stage, or you can exchange envelopes and have the money in the other. You wish to maximise your money. (...) What should you do?1 Here are three forms of reasoning about this situation, which we shall call.. (shrink)
A motivation behind one kind of logical pluralism is the thought that there are different kinds of objects, and that reasoning about situations involving these different kinds requires different kinds of logics. Given this picture, a natural question arises: what kind of logical apparatus is appropriate for situations which concern more than one kind of objects, such as may arise, for example, when considering the interactions between the different kinds? The paper articulates an answer to this question, deploying the methodology (...) of Chunk and Permeate, developed in a different context by Brown and Priest (J Philos Log 33:379–388, 2004). (shrink)
In his article in this issue, " 'How do Mādhyamikas Think?' Revisited," Tom Tillemans reflects on his earlier article "How do Mādhyamikas Think?" (2009), itself a response to earlier work of ours (Deguchi et al. 2008; Garfield and Priest 2003). There is much we agree with in these non-dogmatic and open-minded essays. Still, we have some disagreements. We begin with a response to Tillemans' first thoughts, and then turn to his second thoughts.Tillemans (2009) maintains that it is wrong to attribute (...) to Nāgārjuna or to his Mādhyamika followers a strong dialetheism, according to which some contradictions of the form p ∧ ¬p are to be accepted. He argues that, nonetheless, a weak dialetheism may be implicit in the .. (shrink)
In this issue, Constance Kassor describes Gorampa's attitude to contradictions as they occur in various contexts of Buddhist pursuit. We agree with much of what she says; with some things we do not.First, some preliminary comments, and a fundamental disagreement. Kassor says:Based on . . . [the assumption that Nāgārjuna has a coherent system of thought] one must resolve apparent contradictions in Nāgārjuna's texts in order to maintain the coherency of his logic. The problem with contradictions is that if they (...) are introduced into a classical logical system, that entire system can break down. This is because of the law of explosion—the principle that everything can follow [DGP: does follow] from a contradiction.One .. (shrink)
In recent years, many people writing on set theory have invoked the notion of an indefinitely extensible concept. The notion, it is usually claimed, plays an important role in solving the paradoxes of absolute infinity. It is not clear, however, how the notion should be formulated in a coherent way, since it appears to run into a number of problems concerning, for example, unrestricted quantification. In fact, the notion makes perfectly good sense if one endorses a dialetheic solution to the (...) paradoxes. It then morphs from a supposed solution to the paradoxes into a diagnosis of their structure. In this paper I show how. (shrink)
One of the most dominant approaches to semantics for relevant (and many paraconsistent) logics is the Routley-Meyer semantics involving a ternary relation on points. To some (many?), this ternary relation has seemed like a technical trick devoid of an intuitively appealing philosophical story that connects it up with conditionality in general. In this paper, we respond to this worry by providing three different philosophical accounts of the ternary relation that correspond to three conceptions of conditionality. We close by briefly discussing (...) a general conception of conditionality that may unify the three given conceptions. (shrink)
One of the most dominant approaches to semantics for relevant (and many paraconsistent) logics is the Routley–Meyer semantics involving a ternary relation on points. To some (many?), this ternary relation has seemed like a technical trick devoid of an intuitively appealing philosophical story that connects it up with conditionality in general. In this paper, we respond to this worry by providing three different philosophical accounts of the ternary relation that correspond to three conceptions of conditionality. We close by briefly discussing (...) a general conception of conditionality that may unify the three given conceptions. (shrink)
In ?Definability and the Structure of Logical Paradoxes? (Australasian Journal of Philosophy, this issue) Haixia Zhong takes issue with an account of the paradoxes of self-reference to be found in Beyond the Limits of Thought [Priest 1995. The point of this note is to explain why the critique does not succeed. The criterion for distinguishing between the set-theoretic and the semantic paradoxes offered does not get the division right; the semantic paradoxes are not given a uniform solution; no reason is (...) provided as to why the naïve denotation relation is ?indefinite? (other than that its definiteness leads to contradiction); and the account of the denotation relation given clearly misses the mark, even by consistent standards. (shrink)
Priest (2009) formulates a propositional logic which, by employing the worldsemantics for intuitionist logic, has the same positive part but dualises the negation, to produce a paraconsistent logic which it calls 'Da Costa Logic'. This paper extends matters to the first-order case. The paper establishes various connections between first order da Costa logic, da Costa's own Cω, and classical logic. Tableau and natural deductions systems are provided and proved sound and complete.
The doctrine of the two truths - a conventional truth and an ultimate truth - is central to Buddhist metaphysics and epistemology. The two truths (or two realities), the distinction between them, and the relation between them is understood variously in different Buddhist schools; it is of special importance to the Madhyamaka school. One theory is articulated with particular force by Nagarjuna (2nd ct CE) who famously claims that the two truths are identical to one another and yet distinct. One (...) of the most influential interpretations of Nagarjuna's difficult doctrine derives from the commentary of Candrakirti (6th ct CE). In view of its special soteriological role, much attention has been devoted to explaining the nature of the ultimate truth; less, however, has been paid to understanding the nature of conventional truth, which is often described as "deceptive," "illusion," or "truth for fools." But because of the close relation between the two truths in Madhyamaka, conventional truth also demands analysis. Moonshadows, the product of years of collaboration by ten cowherds engaged in Philosophy and Buddhist Studies, provides this analysis. The book asks, "what is true about conventional truth?" and "what are the implications of an understanding of conventional truth for our lives?" Moonshadows begins with a philosophical exploration of classical Indian and Tibetan texts articulating Candrakati's view, and uses this textual exploration as a basis for a more systematic philosophical consideration of the issues raised by his account. (shrink)
In this paper, I start by showing that sorites paradoxes are inclosure paradoxes. That is, they fit the Inclosure Scheme which characterizes the paradoxes of self-reference. Given that sorites and self-referential paradoxes are of the same kind, they should have the same kind of solution. The rest of the paper investigates what a dialetheic solution to sorites paradoxes is like, connections with a dialetheic solution to the self-referential paradoxes, and related issues—especially so called "higher order" vagueness.
Validity : what follows from what? -- Truth functions,or not -- Names and quantifiers : is nothing something? -- Descriptions and existence : did the greeks worship Zeus? -- Self-reference : what is this chapter about? -- Necessity and possibility : what will be must be? -- Conditionals: what's in an if? -- The future and the past : is time real?? -- Identity and change : is anything ever the same? -- Vaguenes : how do you stop sliding down (...) a slippery slope? -- Probability : the strange case of the missing reference class? -- Inverse probability : you can't be indifferent about it! -- Decision theory : great expectations? -- A little history and some further reading? (shrink)
In early Buddhist logic, it was standard to assume that for any state of a ﬀ airs there were four possibilities: that it held, that it did not, both, or neither. This is the catuskoti (or tetralemma). Classical logicians have had a hard time making sense of this, but it makes perfectly good sense in the semantics of various paraconsistent logics, such as First Degree Entailment. Matters are more complicated for later Buddhist thinkers, such as Nagarjuna, who appear to suggest (...) that none of these options , or more than one, may hold. The point of this paper is to examine the matter, including the formal logical machinery that may be appropriate. (shrink)
One of Da Costa's motives when he constructed the paraconsistent logic Cw was to dualise the negation of intuitionistic logic. In this paper I explore a different way of going about this task. A logic is defined by taking the Kripke semantics for intuitionistic logic, and dualising the truth conditions for negation. Various properties of the logic are established, including its relation to CWo Tableau and natural deduction systems for the logic are produced, as are appropriate algebraic structures. The paper (...) then investigates dualising the intuitionistic conditional in the same way. This establishes various connections between the logic, and a logic called in the literature 'Brouwerian logic' or 'closed-set logic'. (shrink)
Towards NonBeing (Priest, 2005) gives a noneist account of the semantics of intentional operators and predicates. The semantics for intentional operators are modelled on those for the , is given and assessed.
The view that everything is empty (śūnya) is a central metaphysical plank of Mahāyāna Buddhism. It has often been the focus of objections. Perhaps the most important of these is that it in effect entails a nihilism: nothing exists. This objection, in turn, is denied by Mahāyāna theorists, such as Nāgārjuna. One of the things that makes the debate difficult is that the precise import of the view that everything is empty is unclear. The object of this essay is to (...) put the debate in a new light. It does so by proposing a mathematical characterization of Emptiness—that is, the totality of empty things—showing that, whatever it is, it has a definite structure and is not, therefore, to be identified with nothingness. (shrink)
A dialetheia is a sentence, A, such that both it and its negation, ¬A, are true (we shall talk of sentences throughout this entry; but one could run the definition in terms of propositions, statements, or whatever one takes as her favourite truth-bearer: this would make little difference in the context). Assuming the fairly uncontroversial view that falsity just is the truth of negation, it can equally be claimed that a dialetheia is a sentence which is both true and false.
Anyone who is accustomed to the view that contradictions cannot be true, and cannot be accepted, and who reads texts in the Buddhists traditions will be struck by the fact that they frequently contain contradictions. Just consider, for example.
Jaina philosophy provides a very distinctive account of logic, based on the theory of ?sevenfold predication?. This paper provides a modern formalisation of the logic, using the techniques of many-valued and modal logic. The formalisation is applied, in turn, to some of the more problematic aspects of Jaina philosophy, especially its relativism.
A dialetheia is a sentence, A, such that both it and its negation, A, are true (we shall talk of sentences throughout this entry; but one could run the definition in terms of propositions, statements, or whatever one takes as her favourite truth bearer: this would make little difference in the context). Assuming the fairly uncontroversial view that falsity just is the truth of negation, it can equally be claimed that a dialetheia is a sentence which is both true and (...) false. (shrink)