Bas C. Van Fraassen

Personal probability is now a familiar subject in epistemology, together with such more venerable notions as knowledge and belief. But there are severe strains between probability and belief; if either is taken as the more basic, the other may suffer. After explaining the difficulties of attempts to accommodate both, I shall propose a unified account which takes conditional personal probability as basic. Full belief is therefore a defined, derivative notion. Yet we will still be able to picture opinion as follows: my subjective probability is only a grading of the possibilities left open by my beliefs. My conditional probabilities generally derive from the strongest belief I can maintain when admitting the relevant condition

A basic aim of E. Beth's work in philosophy of science was to explore the use of formal semantic methods in the analysis of physical theories. We hope to show that a general framework for Beth's semantic analysis is provided by the theory of semi-interpreted languages, introduced in a previous paper. After developing Beth's analysis of nonrelativistic physical theories in a more general form, we turn to the notion of the 'logic' of a physical theory. Here we prove a result concerning the conditions under which semantic entailment in such a theory is finitary. We argue, finally, that Beth's approach provides a characterization of physical theory which is more faithful to current practice in foundational research in the sciences than the familiar picture of a partly interpreted axiomatic theory

Hilary Putnam's argument against metaphysical realism (commonly referred to as the "model theoretic argument") has now enjoyed two decades of discussion.(1) The text is rich and contains variously construable arguments against variously construed philosophical positions. David Lewis isolated one argument and called it "Putnam's Paradox".(2) That argument is clear and concise; so is the paradoxical conclusion it purports to demonstrate; and so is Lewis' paradox-avoiding solution. His solution involves a position I call "anti-nominalism": not only are classes real, but they are divided into arbitrary and 'natural' classes. The natural classes 'carve nature at the joints', being (as other philosophers might say) the extensions of 'real' properties, universals, or Forms.(3) Thus the argument was turned, in effect, into support for a metaphysical realism stronger than Putnam envisaged

Constructive empiricism is indeed set squarely within a common sense realism that was foreign to much of the empiricist tradition. But I do not see this common sense realism, which I take myself to share with many scientific realists, as harboring or leading to scientific realism. That is in part because of the way I separate the opposition between empiricist and realist understanding of science from other issues that divide us in epistemology. This discussion brought to light our quite different conceptions of what is at issue between empiricists and realists in this area. After a response to McMullin's critique, however, I will be especially concerned to respond to his challenging proposal for a shift in the debate over realism concerning the sciences.

Professor Massey's exposition and analysis [5] of Professor Grünbaum's writings on metric aspects of space seem to me both very helpful in understanding those writings and to contain a considerable original contribution to the subject. Nevertheless I would like to argue that there is an alternative to Massey's explication which seems to me more faithful to Grünbaum's remarks; it seems at least to have the virtue of not forcing Grünbaum to reject the usual mathematical definitions of the notions used

Delivered on the occasion of the 2009 “Giulio Preti Prize”, this lecture examines and questions the contrast between the sense of intellectual crisis in the scientific world of the first decades of the 20th century and the absence of any such sense of crisis in current philosophy. Starting in the 19the century, we were confronted with changes in perspective that affected our relation to the universe we live in as well as to our own language and logic. Not only how we see ourselves but the tools by means of which we think about ourselves came into question. How would it be possible to rationally assess conceptual change that affects the very form of reasoning by which we assesssuch changes? Such are the paradoxes to which philosophers and scientists, in the throes of crisis in the first half of the 20th century, tried to respond. Philosophers today may seemingly have overcome those aporias that vexed their recent predecessors, in denial of the existence of a crisis that should actually be a fecund source for reflection.

Michel Ghins and I are both empiricists, and agree significantly in our critique of “traditional” empiricist epistemology. We differ however in some respects in our interpretation of the scientific enterprise. Ghins argues for a moderate scientific realism which includes the view that acceptance of a scientific theory will bring with it belief in the existence of all those entities, among the entities the theory postulates, that satisfy certain criteria. For Ghins these criteria derive from the criteria for legitimate affirmation of existence for any entities, the directly observable ones not being privileged in that respect. They are roughly that the putatively existing entity should according to the accepted theory manifest itself in our experience, and display a certain permanence and invariance. My disagreement on this topic derives from a larger difference concerning the relation between experience, existence, and theory