Cut-free sequent and tableau systems for propositional Diodorean modal logics

We present sound, (weakly) complete and cut-free tableau systems for the propositional normal modal logicsS4.3, S4.3.1 andS4.14. When the modality is given a temporal interpretation, these logics respectively model time as a linear dense sequence of points; as a linear discrete sequence of points; and as a branching tree where each branch is a linear discrete sequence of points.Although cut-free, the last two systems do not possess the subformula property. But for any given finite set of formulaeX the superformulae involved are always bounded by a finite set of formulaeX* _L depending only onX and the logicL. Thus each system gives a nondeterministic decision procedure for the logic in question. The completeness proofs yield deterministic decision procedures for each logic because each proof is constructive.Each tableau system has a cut-free sequent analogue proving that Gentzen's cut-elimination theorem holds for these latter systems. The techniques are due to Hintikka and Rautenberg.Presented byDov M. Gabbay     

Parasuicide and Use of Intoxicants Among Norwegian Adolescents

Self-reported history of parasiticide was analyzed with respect to use of intoxicants in a national sample of 12,000 Norwegian adolescents. The proportion of parasuicides was 8.3%, being higher among girls and among those living without both parents, and it increased with age, with use of intoxicants, depression, and loneliness. Calculations of relative risks and adjusted odds ratios demonstrated positive associations between parasiticide and use of intoxicants, and no significant gender differences were found. The findings are discussed with reference to impacts of intoxication and risk-taking behavior.     

The Linguistic Determination of Conscious Thought Contents

In this paper we address the question of what determines the content of our conscious episodes of thinking, considering recent claims that phenomenal character individuates thought contents. We present one prominent way for defenders of phenomenal intentionality to develop that view and then examine ‘sensory inner speech views’, which provide an alternative way of accounting for thought‐content determinacy. We argue that such views fare well with inner speech thinking but have problems accounting for unsymbolized thinking. Within this dialectic, we present an account of the nature of unsymbolized thinking that accords with and can be seen as a continuation of the activity of inner speech, while offering a way of explaining thought‐content determinacy in terms of linguistic structures and representations.