Tjerk Gauderis

_Abduction of generalizations_ is the process in which explanatory hypotheses are formed for an observed, yet puzzling generalization such as ``pineapples taste sweet" or ``rainbows appear when the sun breaks through the rain". This phenomenon has received little attention in formal logic and philosophy of science. The current paper remedies this lacuna by first giving an overview of some general characteristics of this process, elaborating on its ubiquity in scientific and daily life reasoning. Second, the adaptive logic $\LAG$ is presented to explicate this process formally.

This paper addresses the question of how scientists determine which type of hypothesis is most suitable for tackling a particular problem by examining the historical case of the anomalous β spectrum in early nuclear physics, a puzzle that occasioned the most diverse hypotheses amongst physicists at the time. It is shown that such determinations are most often implicitly informed by scientists' individual perspectives on the structural relations between the various elements of the theory and the problem at hand. In addition to this main result, it is suggested that Wolfgang Pauli's neutrino idea may well have been an adaptation of Ernst Rutherford's original and older neutron idea, which would provide evidence that the adaptation of older ideas is a more common practice than is often thought.

In the literature on doxastic attitudes, the notion ‘belief’ is used in both a coarse-grained and a fine-grained manner. While the coarse-grained notion of ‘belief,’ as the doxastic attitude that expresses any form of assent to its content, is a useful technical concept, the fine-grained notion, which tries to capture the folk notion of ‘belief’ in contrast with other doxastic concepts such as ‘acceptance’ or ‘degrees of confidence,’ is utterly ambiguous. In order to dispel this ambiguity, I introduce first a new framework for describing doxastic attitudes that does not rely on a specific fine-grained primitive notion of ‘belief.’ This framework distinguishes two different doxastic attitudes, i.e. the theoretical and the practical, and explains how various doxastic concepts such as ‘accepting,’ ‘having a degree of confidence’ and the folk notion of ‘belief’ all describe a particular interpretation of one or both of the distinguished doxastic attitudes. Next, by focusing on ongoing debates over the difference between ‘acceptance’ and ‘belief’ on the one hand and between ‘degrees of confidence’ and ‘(plain) belief’ on the other, I argue that much precision can be gained in philosophical analysis by taking a reductionist stance concerning any specific fine-grained and primitive notion of ‘belief.’