The standard use of the propositional calculus ('P.C.?) in analyzing the validity of inferences involving conditionals leads to fallacies, and the problem is to determine where P.C. may be ?safely? used. An alternative analysis of criteria of reasonableness of inferences in terms of conditions of justification rather than truth of statements is proposed. It is argued, under certain restrictions, that P. C. may be safely used, except in inferences whose conclusions are conditionals whose antecedents are incompatible with the premises in (...) the sense that if the antecedent became known, some of the previously asserted premises would have to be withdrawn. (shrink)

The paper begins by focusing the basic idea that Gestalt phenomena belong not only to the realm of perception but to the realm of inference. It is shown that Gestalt effects often occur both in counterfactual and in ampliative – i.e. inductive and abductive – reasoning. The main thesis of the paper is that the common feature of such forms of non-deductive reasoning is provided by a rational selection between incompatible conclusions, where rationality lies in the choice of the alternative (...) which preserves the maximum of background information. It is also stressed a distinction between a weak and a strong notion of incompatibility. Such distinction may help in giving account of some alleged Gestalt phenomena which have been recognized in theory construction and theory change. (shrink)

The aim of the paper is to outline a treatment of cotenability inspired by a perspective which had strong roots in ancient logic since Chrysippus and was partially recovered in the XX Century by E. Nelson and the exponents of so-called connexive logic. Consequential implication is a modal reinterpretation of connexive implication which permits a simple reconstruction of Aristotle's square of conditionals, in which proper place is given not only to ordinary cotenability between A and B, represented by ¬, but (...) to its “secondary” variant ¬ . After showing that logics of strict implication, of Stalnaker-Lewis conditionals and of relevant implication do not satisfy the intuitive properties required for cotenability , it is proved that such conditions are satisfied by consequential cotenability and by its secondary variant . The notions of strong cotenability and of bilateral cotenability are then introduced: the latter stands to standard cotenabilty as contingency stands to possibility, and in Section 9 it is shown to be a useful tool in the reconstruction of Boethius' theory of adjuncta. (shrink)

To explain the phenomena in the world of our experience, to answer the question “why?” rather than only the question “what?”, is one of the foremost objectives of all rational inquiry; and especially, scientific research in its various branches strives to go beyond a mere description of its subject matter by providing an explanation of the phenomena it investigates. While there is rather general agreement about this chief objective of science, there exists considerable difference of opinion as to the function (...) and the essential characteristics of scientific explanation. In the present essay, an attempt will be made to shed some light on these issues by means of an elementary survey of the basic pattern of scientific explanation and a subsequent more rigorous analysis of the concept of law and of the logical structure of explanatory arguments. (shrink)