While logical theories of information attitudes, such as knowledge, certainty and belief, have flourished in the past two decades, formalization of other facets of rational behavior have lagged behind significantly. One intriguing line of research concerns the concept of intention. I will discuss one approach to tackling the notion within a logical framework, based on a database perspective.

This article is a critical review of Cocchiarella’s theory of reference. In conceptual realism, there are two central distinctions regarding reference: first, between active and deactivated use of referential expressions, and, second, between using referential expressions with and without existential presupposition. Cocchiarella’s normative restrictions on the existential presuppositions of reference lead to postulating two fundamentally different kinds of objects in conceptual realism: realia or concrete objects, on the one hand, and abstract intensional objects or nonexistents, on the other. According to (...) Cocchiarella, nonexistents can be referred to only without existential presuppositions. However, referring to nonexistents with existential presuppositions is an ordinary human practice. To account for this fact, Cocchiarella’s normative theory of reference should be supplemented by a descriptive account of referring. (shrink)

We define intuitionistic subatomic natural deduction systems for reasoning with elementary would-counterfactuals and causal since-subordinator sentences. The former kind of sentence is analysed in terms of counterfactual implication, the latter in terms of factual implication. Derivations in these modal proof systems make use of modes of assumptions which are sensitive to the factuality status of the formula that is to be assumed. This status is determined by means of the reference proof system on top of which a modal proof system (...) is defined. The introduction and elimination rules for counterfactual (resp. factual) implication draw on this status. It is shown that derivations in the systems normalize and that normal derivations have the subexpression/subformula property. An intuitionistically acceptable proof-theoretic semantics is formulated in terms of canonical derivations. The systems are applied to so-called counterpossibles and to related constructions. (shrink)