Bolzano's deducibility and tarski's logical consequence

In this paper I argue that Bolzano's concept of deducibility and Tarski's concept of logical consequence differ with respect to their philosophical intent. I distinguish between epistemic and ontic approaches to logic, and argue that Bolzano's deducibility presupposes an epistemic approach, while Tarski's logical consequence presupposes an ontic approach.     

Dialectic and Dialetheism

In this article, I consider the possibility of interpreting Hegel's dialectic as dialetheism. After a first basic recapitulation about the meaning of the words ‘dialetheism’ and ‘dialectic’ and a consideration of Priest's own account of the relation between dialectical and dialetheic logic in 1989, I discuss some controversial issues, not directly considered by Priest. As a matter of fact, the reflection on paraconsistent logics and dialetheism has enormously grown in recent years. In addition, the reception of Hegel's logic and metaphysics has also impressively improved. So I suggest that the discussion about the binomial dialectic/dialetheism should be reopened, on these new bases.     

Theism and Dialetheism

The divine attributes of omniscience and omnipotence have faced objections to their very consistency. Such objections rely on reasoning parallel to semantic paradoxes such as the Liar or to set-theoretic paradoxes like Russell's paradox. With the advent of paraconsistent logics, dialetheism—the view that some contradictions are true—became a major player in the search for a solution to such paradoxes. This paper explores whether dialetheism, armed with the tools of paraconsistent logics, has the resources to respond to the objections levelled against the divine attributes.     

Robert Greville on Sins,Privations, and Dialetheism

In the history of Western philosophy, dialetheism – the view that some sentences are both true and false – has been unpopular. This paper recovers a previously overlooked episode in the history of dialetheism. Specifically, it reconstructs a section of Robert Greville's The Nature of Truth (1640) in order to show that he was a dialetheist. Greville's consideration of the view that evil is a privation led him to endorse the claim that sinful acts are contradictory; they are the subjects of both being and non-being. The paper also explores responses to Greville from John Wallis and Nathaniel Culverwell.     

Variations on intra-theoretical logical pluralism: internal versus external consequence

Philosophical Studies - Intra-theoretical logical pluralism is a form of meaning-invariant pluralism about logic, articulated recently by Hjortland (Australas J Philos 91(2):355–373, 2013)....     

Dialetheism and the Impossibility of the World

This paper first offers a standard modal extension of dialetheic logics that respect the normal semantics for negation and conjunction, in an attempt to adequately model absolutism, the thesis that there are true contradictions at metaphysically possible worlds. It is shown, however, that the modal extension has unsavoury consequences for both absolutism and dialetheism. While the logic commits the absolutist to dialetheism, it commits the dialetheist to the impossibility of the actual world. A new modal logic AV is then proposed which avoids these unsavoury consequences by invalidating the interdefinability rules for the modal operators with the use of two valuation relations. However, while using AV carries no significant cost for the absolutist, the same isn't true for the dialetheist. Although using AV allows her to avoid the consequence that the actual world is an impossible world, it does so only on the condition that the dialetheist admits that she cannot give a dialetheic solution to all self-referential semantic paradoxes. Thus, unless there are any further available modal logics that don't commit her to the impossibility of the actual world, the dialetheist is faced with a dilemma. Either admit that the actual world is an impossible world, or admit that her research programme cannot give a comprehensive solution to the self-referential paradoxes.     

Correction to: Variations on intra-theoretical logical pluralism: internal versus external consequence

Philosophical Studies - In the original publication of the article, in Definition 4, the sixth line which reads as     

Soames on the logical empiricists on truth,meaning, convention,and logical truth

Philosophical Studies -     

Assertion, inference, and consequence

In this paper the informativeness account of assertion (Pagin in Assertion. Oxford University Press, Oxford, 2011) is extended to account for inference. I characterize the conclusion of an inference as asserted conditionally on the assertion of the premises. This gives a notion of conditional assertion (distinct from the standard notion related to the affirmation of conditionals). Validity and logical validity of an inference is characterized in terms of the application of method that preserves informativeness, and contrasted with consequence and logical consequence, that is defined in terms of truth preservation. The proposed account is compared with that of Prawitz (Logica yearbook 2008. pp. 175?C192. College Publications, London, 2009).     

Modality,invariance, and logical truth

Conclusion Let us sum up. We began with the question, What is the interest of a model-theoretic definition of validity? Model theoretic validity consists in truth under all reinterpretations of non-logical constants. In this paper, we have described for each necessity concept a corresponding modal invariance property. Exemplification of that property by the logical constants of a language leads to an explanation of the necessity, in the corresponding sense, of its valid sentences. I have fixed upon the epistemic modalities in characterizing the logical constants: to be a logical constant in the language of a population is to be invariant over a modality describing complete possible epistemic states of that population (or an idealized analogue thereof). The grounds for this characterization are these: (1) It leads, I believe, to an extensionally reasonable demarcation of the logical constants, including clear cases and excluding clear non-cases. It gives a principled criterion for deciding unclear cases. (2) It provides an analysis of the topic-neutrality of logic. (3) It leads to an explanation of the epistemic necessity of the logical truths in terms of the topic-neutrality of the logical constants.All the same, it is reasonable to ask, even if the suggested demarcation of logic is extensionally correct, whether it can reasonably be expected to be fundamental. The epistemic invariance of an expression is a rather striking property, one which we should want to explain. What is missing, then, is an explanation of the distinguishing epistemic properties of the constants in terms of more fundamental properties involving their understanding and use. It would be these that properly define the nature, not just the extent, of logic.     

The Sufi Path of Dialetheism: Gluon Theory and Wahdat al-Wujud

The theory of Wahdat al-Wujūd, or as it is called in English the Oneness of Being, is the core idea of Sufism. The founder of this theory is Ibn ‘Arabī. There are contradictions in Ibn ‘Arabī’s theory of the Oneness of Being. The most important one, which is my main concern in this essay, occurs in his explanation of the relation between Being, which is, according to him, the only real being, and other beings. According to Ibn ‘Arabī, Being is identical and also non-identical with beings. Different philosophers, through hundreds of years, tried to dissolve such contradictions, by proposing consistent readings of Ibn ‘Arabī’s theory of the Oneness of Being. I will not follow this path. Instead, I take the theory of the Oneness of Being to be a dialetheic one, that is, according to this theory there are true contradictions. Thus, I claim that one can have a paraconsistent semantics of the theory of the Oneness of Being. To do so, I appeal to Graham Priest’s Gluon theory. Gluon theory concerns the problem of unity, that is, what makes the plurality of an object’s parts into a whole? I give a translation of the theory of the Oneness of Being into Gluon theory, and show how Gluon theory explains the theory of the Oneness of Being.     

Emergence: logical, functional and dynamical

Philosophical accounts of emergence have been explicated in terms of logical relationships between statements (derivation) or static properties (function and realization). Jaegwon Kim is a modern proponent. A property is emergent if it is not explainable by (or reducible to) the properties of lower level components. This approach, I will argue, is unable to make sense of the kinds of emergence that are widespread in scientific explanations of complex systems. The standard philosophical notion of emergence posits the wrong dichotomies, confuses compositional physicalism with explanatory physicalism, and is unable to represent the type of dynamic processes (self-organizing feedback) that both generate emergent properties and express downward causation.