Javier Belastegui Lazcano

Our usual explication of a logic through an axiomatic calculus is structurally foundationalist. Justification gets transferred by applying rules finitely many times from already justified sentences to new sentences in a linear-like fashion, by starting from a base of non-to-be justified sentences (i.e. the axioms). In contrast, this paper develops a coherentist approach to classical propositional logic, by explaining the fundamental notion of deducibility in terms of a primitive notion of logical coherence. This is done by introducing a calculus consisting of rules that capture the properties of classical consistency. The basic logical reasoning process explicated is that of constructing consistent sets of formulas. I show how to define classical deducibility in terms of the primitive relation of logical coherence. As applications, I use the coherence calculus to provide a non-semantic proof of the consistency of an axiomatic calculus for classical propositional logic, I show how the system avoids an impossibility result for semantic resemblance proven by Leitgeb, I show that the strategy of defining deducibility from coherence does not work for intuitionistic logic and I briefly compare my approach to the Simple Theory of Propositions put forward by Stalnaker and Fritz.

A core assumption of the conceptual spaces approach is that concepts, which are represented as regions in a space, have prototype structure. This may suggest that the framework cannot be successfully applied to the study of classical concepts based on definitions given by necessary and sufficient conditions. The aim of this paper is to show that this is not the case. By selecting an appropriate space (namely the Cantor space), the framework of conceptual spaces is applied to the study of classical concepts. The points of the space are sets of qualities representing objects, and the topology reflects similarities in respects between these objects. Each classical concept is represented as a region, corresponding to all those objects that share the qualities defining the concept. This model of classical concepts is argued to have several philosophically interesting consequences. First, these regions satisfy plausible adequacy conditions linking similarity and concepts, including Douven-Gärdenfors’s Design Principle of Well-Formedness. Second, these regions are geometrically well-behaved, for they are closed and convex regions with empty boundaries that can also be represented as geometric projections that measure how far an object is from satisfying the definition of the concept. Finally, these regions satisfy a compositionality condition, for they can be combined with each other by combining their definitions. This fact is used to discuss some consequences for the notion of Kantian analyticity as concept containment, in relation to hyperintensional approaches to meaning.

The aim of this paper is to propose a qualitative approach to the theory of conceptual spaces, in contrast to the usual metric framework. This requires qualitative notions of similarity, simple concepts, prototypes and conceptual categorisation. For this purpose, I will introduce three mathematical models for conceptual spaces. The first one is topological and has been proposed by Mormann. The other two are new and are based on atomistic orders and similarity relations. I will discuss how each of them deals with the Design Principles proposed by Douven and Gärdenfors and with further Adequacy Conditions. Despite being apparently different, I will show that these three models are mathematically equivalent. Finally, I will address three objections to the present approach. The first one says that the qualitative notion of a prototype is a bad analogue of the metric one. The second one suggests that, in contrast to the Voronoi construction, the function qualitatively representing the conceptual categorisation process is arbitrary. The last one appeals to Goodman’s companionship and imperfect community problems to show that there is a flaw in defining simple concepts from similarity relations.

In this paper we propose and defend the _Synonymy account_, a novel account of metaphysical equivalence which draws on the idea (Rayo in _The Construction of Logical Space_, Oxford University Press, Oxford, 2013) that part of what it is to formulate a theory is to lay down a theoretical hypothesis concerning logical space. Roughly, two theories are synonymous—and so, in our view, equivalent—just in case (i) they take the same propositions to stand in the same entailment relations, and (ii) they are committed to the truth of the same propositions. Furthermore, we put our proposal to work by showing that it affords a better and more nuanced understanding of the debate between Quineans and noneists. Finally we show how the _Synonymy account_ fares better than some of its competitors, specifically, McSweeney’s (Philosophical Perspectives 30(1):270–293, 2016) epistemic account and Miller’s (Philosophical Quarterly 67(269):772–793, 2017) hyperintensional account.

The aim of this paper is to provide a complete Natural Kind Semantics for an Essentialist Theory of Kinds. The theory is formulated in two-sorted first order monadic modal logic with identity. The natural kind semantics is based on Rudolf Willes Theory of Concept Lattices. The semantics is then used to explain several consequences of the theory, including results about the specificity (species–genus) relations between kinds, the definitions of kinds in terms of genera and specific differences and the existence of negative kinds. First, I show under which conditions the Hierarchy principle, which has been subjected to counterexamples in the literature, holds. I also show that a different principle about the species–genus relations between kinds, namely Kant’s Law, follows from the essentialist theory. Second, I introduce two new operations for kinds and show that they can be used to provide traditional definitions of kinds in terms of genera and specific differences. Finally, I show that these operations of specific difference induce, for each kind, a uniquely specified contrary kind and a uniquely specified subcontrary kind, which can be used as semantic values for non-classical predicate negations of kind terms.