It is widely acknowledged that scientific discourse is full of metaphors. Does this undermine the commitment of such a discourse to truth and objective knowledge? Does this mean that the scientist (any scientist) is, after all, only a ‘rhetorician in disguise’?In what follows I will try to argue for quite the opposite view. I will show that metaphor is not simply a rhetorical device -at least, in the derogatory sense of rhetoric. There are metaphors which can be used to increment our knowledge, and to explore new conceptual domains. This appears to be the case not only for natural science, but also for the so-called ‘sciences of the social’.

Logicians treat assertions as true, believed or merely hypothesized sentences. The reasoner who uses them, however, is the sole referee who can validate their truth, their aptness to describe an actual situation, their strength (as beliefs) or the relevance of their use in the current logical context. Moreover, the reasoner actively counts on these factors, as part of the reasoning process itself, and should normally be capable, when asked to do so, to assign consistently relative strengths to the assertions used. The paper assumes, first, that assertions have -each- an associated, measurable strength, and that, second, this strength has significant -and measurable- effects on the truth of the sentences, the validity of the conclusion and the soundness of the reasoning. The concepts and formulas required for this are explored, and a semantics and proof theory for a sentential calculus of assertions are proposed as a natural extension of ordinary two-valued reasoning. The resulting theory, though reminiscent of Probability,is autonomous, self-contained and of a purely logical nature.

A new problem about 'if...then...' is posed which is related to Curry's paradox much as the barber's paradox parallels Russell's paradox. However, it is not obvious how to solve it.

Beyond any doubt the pragmatical-based improvements introduced in the rules of inference during the process of refinement of a legal expert system may be efficient but they hardly will be capable to provide a point of reference for a more general correctness measure. During the refinement of KBSLEX the debate of the Theory of Legal Argument has contributed to illuminate the point suggesting that the modeling of legal reasoning and legal decision making should be grounded on a logical approach but without limiting itself to the tools of the classical logic.

Classical approaches such as frames, scripts,... have been unable to deal with the kind of inferences necessary in natural language processing situations such as text comprehension. Shastri & Ajjanagadde (1993), proposed a local connectionist model for the sort of reasoning requiring such a fast inference. The problem with this system is that it controls only the adequacy of argument- fillers, leaving untouched the activation control issue, namely, why we perform certain inferences, and not others, in a given situation. The aim of this paper is to examine how a focus, in the sense of Grosz (1981). could operate as a theoretic constraint with the above reasoner system to handle two aspects: inference control and anaphora resolution (i.e., antecedent activation), during text understanding.

Attempts to give a Logic or Semantics for vague predicates and to defuse the Sorites paradoxes have been largely a failure. We point out yet another problem with these predicates which has not been remarked on before,namely that different people do and must use these predicates in individually different ways. Thus even if there were a semantics for vague predicates, people would not be able to share it. To explain the occurrence nonetheless of these troublesome predicates in language, we propose a different approach based on asking the question, “How do these vague predicates help people to communicate with each other?” We show that in general, even though different people assign different extensions to vague predicates, they usually benefit from receiving information framed in terms of them.

The aim of this paper is to investigate the preconditions and the limits of rational reconstruction in the philosophy of language, as these preconditions and limits can be deduced from Wittgenstein’s arguments against philosophical constructivism. It will be shown that a main precondition of reconstructions in the field of language is the existence of non-arbitrary patterns of linguistic use, while the limits of this kind of theoretical enterprise derive precisely from the absence of such patterns.

The main purpose of this paper is to show that Kant’s transcendental philosophy is tacitly laden with the structures of modern modal thought. More exactly, the surprising parallelism which seems to exist between Kant’s manner of defining necessity (and, on this basis, nomicity) and the modern approaches of the same concepts in the frame of “possible worlds philosophy” is stressed. A new interpretation of the Categorical Imperative is also offered on this basis.

This short paper about fuzzy set-based approximate reasoning first emphasizes the three main semantics for fuzzy sets: similarity, preference and uncertainty. The difference between truth-functional many-valued logics of vague or gradual propositions and non fully compositional calculi such as possibilistic logic (which handles uncertainty) or similarity logics is stressed. Then, potentials of fuzzy set-based reasoning methods are briefly outlined for various kinds of approximate reasoning: deductive reasoning about flexible constraints, reasoning under uncertainty and inconsistency, hypothetical reasoning, exception-tolerant plausible reasoning using generic knowledge, interpolative reasoning, and abductive reasoning (under uncertainty). Open problems are listed in the conclusion.

This paper deals with the relation with Fuzzy Logic of some of the ideas of Karl Menger published between 1942 and 1966 and concerning what he called “Hazy Sets”, Probabilistic Relations and Statistical Metric Spaces. The author maintains the opinion that if Lofti A. Zadeh is actually the father of Fuzzy Logic, Menger not only was a forerunner of this field but that his ideas were and still are influential on it.