Recently several authors have stressed and illustrated the importance of including a second kind of negation (explicit negation) in logic programs besides \negation as failure", and its use in deductive databases, knowledge representation, and nonmonotonic reasoning. By introducing explicit negation into logic programs contradiction may appear. In this work we present two approaches for dealing...

The problems of the meaning and function of negation are disentangled from ontological issues with which they have been long entangled. TIle question of the function of negation is the crucial issue separating relevant and paraconsistent logics from classical theories. The function is illuminated by considering the inferential role of contradictions, contradiction being parasitic on negation. T...

After observing a contradiction between the 'official' ideology defined by open-source licenses and the actual behavior of hackers, we examine the actual customs which regulate the ownership and control of open-source software. We discover that they imply an underlying theory of property rights homologous to the Lockean theory of land tenure. We relate that to an analysis of the hacker culture ...

1. Genuine worlds, ersatz worlds David Lewis has argued that impossible worlds are nonsense. 1 If there were such worlds, one would have to distinguish between the truths about their contradictory goings-on and contradictory falsehoods about them. One would have to distinguish between, say, the alleged truth (1a) In so-and-so world pigs can fly; and in that world pigs also cannot fly, and the c...

Despite efforts to identify masturbation as a strategy to improve sexual health, promote relational intimacy, and reduce unwanted pregnancy, STIs, and HIV transmission, masturbation as a context for healthy sexual development has been met with silence or trepidation in the scientific and educational communities. Relegated to the realm of commercial media, rather than rational discourse in famil...

Adherents of two-dimensionalist semantics have devised a powerful argument to show that the Kripke-Putnam semantics is in need of an overhaul. Kripke and Putnam take “Water is H2O” to be necessary as well a posteriori. But that cannot be true. For to claim that a proposition is necessary is to claim that it is true in all contexts, whilst to maintain that it is a posteriori or informative is to...

Adherents of two-dimensionalist semantics have devised a powerful argument to show that the Kripke-Putnam semantics is in need of an overhaul. Kripke and Putnam take “Water is H2O” to be necessary as well a posteriori. But that cannot be true. For to claim that a proposition is necessary is to claim that it is true in all contexts, whilst to maintain that it is a posteriori or informative is to...

This is the seventh article in a regular series on object-oriented type theory, aimed specifically at non-theoreticians. So far, we have built up a model of objects as simple records, which are instances of corresponding record types [1]. Initially, we took the seemingly attractive view that a programmer's class in C++ or Java corresponds in some way to a type in the formal model, and that a co...