This paper argues that existence claims for theoretical entities must be based on more than their role in one theory. The supplementary evidence should be either observation, whether direct or indirect, or the possibility of detaching the existence claim from one particular theory. A logical schematism for the latter type of support is developed.

There are a number of dimensions to the realism-nominalism controversy. The topics of debate comprise: necessary connections and causality, dispositions and counterfactuals, space and time, the existence of abstract entities and mathematical objects, the existence of the theoretical entities of science. On all these except the last, Sellars takes a non-realist line: and on all these except the last, I agree with him to the extent that I presently have an opinion on them. But Sellars is a scientific realist, encapsulating (...) this realism in the dictum: “to have good reason for holding a theory is ipso facto to have good reason for holding that the entities postulated by the theory exist”. (shrink)

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. (shrink)

Bas van Fraassen in [4] has recently tried to use modal logic to solve the measurement problem of quantum mechanics. His model is based on a method of expressing quantum states developed by Hugh Everett [1] called the “relative state formulation.” Unfortunately, Everett's mathematics cannot be generalized as van Fraassen requires. The difficulty itself is elementary enough. But a revision of van Fraassen's postulates can save the mathematics only on pain of making the whole study irrelevant to the physics. I (...) shall explain the dilemma in this note. In a later paper [5], van Fraassen avoids this dilemma by developing an abstract modal interpretation which does not rely on any expression for quantum states. (shrink)

This is a long critical evaluation of W. Sellars's book.

Our ancestors believed in many things which did not exist—gods, witches, the luminiferous ether, phlogiston, reincarnated souls, sense-data, conceptual analysis, and the like. But they had no better ways of coping with the irradiations beating down upon their sense organs. So they were justified in making assertions which did not bear those desirable relations to things in the world—relations like naming and truth—which we like to think are sustained by our own assertions. This fact brings out the difference between the (...) results of rational, sincere and industrious inquiry on the one hand, and truth on the other. Our ancestors had all the former virtues, but somehow these did not suffice to get them in touch with reality. Since we can no longer dismiss them as blinded by prejudice, passion and superstition, we would like some philosophical way of explaining our superiority to them. (shrink)

Modalities explained through the idea of a logical space.

In The Structure of Scientific Inference, Mary Hesse has argued for a realist interpretation of science. Her realism, however, is not to be understood in the context of the traditional realist/instrumentalist debate within the philosophy of science. That debate focused on the question of whether or not science did anything other than systematize the empirical data given in our experience. The traditional realist answered “yes” and most frequently described the theoretical statements of science, not only as true, but also as (...) providing descriptions of the world. The instrumentalist on the other hand answered “no” and ascribed no descriptive force to the theoretical statements of science. However, according to Hesse, neither party in the contemporary realism debate assumes the notion of an empirical given. Consequently, the present dispute must be understood as taking place on a level which is logically prior to its predecessor. (shrink)