A construction is described of a cartesian closed category A with exactly two elements out of a C-monoid such that can be recovered from A without reference to the construction.

This paper discusses several types of relevance criticism within dialogue. Relevance criticism is a way one could or should criticize one's partner's contribution in a conversation as being deficient in respect of conversational coherence. The first section tries to narrow down the scope of the subject to manageable proportions. Attention is given to the distinction between criticism of alleged fallacies within dialogue and such criticism as pertains to argumentative texts. Within dialogue one may distigguish tenability criticism, connection criticism, and narrow-type (...) relevance criticism. Only the last of these three types of criticism constitutes a charge of fallacy and carries with it a burden of proof. In the second it is observed that a full study of narrow-type relevance criticism would require the construction of complicated, many-layered, dialogue systems. Such a study can, however, be profitably preceded by setting up profiles of dialogue that help us discuss the ins and outs of certain types of move. This is illustrated with an example. (shrink)

During the last forty or so years it has become popular to offer explanations of logical notions in terms of games. There is no doubt that many people find games helpful for understanding various logical phenomena. But we ask whether anything is really 'explained' by these accounts, and we analyse Paul Lorenzen's dialogue foundations for constructive logic as an example. The conclusion is that the value of games lies in their ability to provide helpful metaphors and representations, rather than in (...) any true conceptual analysis. In fact some of the standard explanations of logical notions in terms of competitive games simply don't work. /// [Erik C. W. Krabbe] In an attempt to redeem the Lorenzen-type dialogues from their detractors, it is perhaps best first to provide a survey of the various benefits these dialogues have been supposed to yield. This will be done in Section I. It will not be possible, within the confines of this paper, to scrutinize them all, but in Section II we shall delve deeper into the capacity of this type of dialogue to yield a model for the immanent criticism of philosophical positions. Section III will extend the concept of a dialogue in such a way as to conform better with our intuitive conceptions of what a rational discussion of a position should contain. This will be followed up by a concept of 'winning a dialogue' that takes position midway between the old conception of 'winning one play' and that of the full-fledged presentation of a winning strategy . Concepts of 'rational discussion' are thus shown to be, plausibly, more fundamental than those of proof. In Section IV, I shall discuss the specific problems about dialogical foundations put forward by Wilfrid Hodges. (shrink)