Grünbaum has argued that the Lorentz-Fitzgerald contraction hypothesis is not ad hoc since the Kennedy-Thorndike experiment can be used to provide a test that is significantly different from that provided by the Michelson-Morley experiment. In the first part of the paper, I show that the differences claimed by Grünbaum to hold between these two experiments are not sufficient for establishing independent testability. A dilemma is developed: either the Kennedy-Thorndike experiment, because of experimental realities, cannot test the uncontracted Fresnel aether theory, or if experimental difficulties are ignored, the Kennedy-Thorndike experiment degenerates into a version of the Michelson-Morley experiment. The second part of the paper is a feasibility study of the prospects for defining experimental types according to aims of measurement and determination. This approach is applied to the contraction hypothesis, where it is suggested that the usual analysis of independent testability be modified.

Kripke and Putnam have proposed that terms may be introduced to refer to theoretical entities by means of causal descriptions such as 'whatever causes observable effects O'. It is argued that such a reference-fixing definition is ill-formed and that theoretical beliefs must be involved in fixing the reference of a theoretical term. Some examples of reference-fixing are discussed e.g., the term 'electricity'. The Kripke-Putnam theory can not give an account of how terms may be introduced into science and then subsequently be discovered to be non-referring. A modified account of reference-fixing is suggested in which terms such as Gilbert's ‘electric effluvia’ and ‘phlogiston’ can be introduced into science and then be found to lack a reference.

A general form is proposed for epistemological theories, the relevant factors being: the family of epistemic judgments, the epistemic state, the epistemic commitment (governing change of state), and the family of possible epistemic inputs (deliverances of experience). First a simple theory is examined in which the states are probability functions, and the subject of probability kinematics introduced by Richard Jeffrey is explored. Then a second theory is examined in which the state has as constituents a body of information (rational corpus) and a recipe that determines the accepted epistemic judgments on the basis of this corpus. Through an examination of several approaches to the statistical syllogism, a relation is again established with Jeffrey's generalized conditionalization.

We propose an “explanation scheme” for why the Gibbs phase average technique in classical equilibrium statistical mechanics works. Our account emphasizes the importance of the Khinchin-Lanford dispersion theorems. We suggest that ergodicity does play a role, but not the one usually assigned to it.

The relationship between vague statements and fuzzy sets is examined. It is shown that the probability of vague statements may be defined in a manner analogous to that discussed in Reichenbach's logic of weight.

The prevalence of optimality models in the literature of evolutionary biology is testimony to their popularity and importance. Evolutionary biologist R. C. Lewontin, whose criticisms of optimality models are considered here, reflects that “optimality arguments have become extremely popular in the last fifteen years, and at present represent the dominant mode of thought.”

Although optimality models have received little attention in the philosophical literature, these models are very interesting from a philosophical point of view. As will be argued, optimality models are central to evolutionary thought, yet they are not readily accomodated by the traditional view of scientific theories. According to the traditional view, we would expect optimality models to employ general, empirical laws of nature, but they do not. Fortunately, the semantic view of scientific theories, a recent alternative to the traditional view, more readily accomodates optimality models. As we would expect on the semantic view, optimality models can be construed as specifications of ideal systems. These specifications may be used to describe empirical systems—that is, the specifications may have empirical instances. But the specifications are not empirical claims, much less general, empirical laws.

Although philosophers have yet to discuss the general features and uses of optimality models, these topics have stimulated much recent discussion among evolutionary biologists. Their discussions raise a number of precautions concerning the proper use of optimality models. Moreover, many of their caveats can be interpreted as general reminders that 1) optimality models specify ideal systems whose empirical instantiations may be quite restricted, and that 2) optimality models should not be construed as general, empirical laws. As G. F. Oster and E. O. Wilson caution, “the prudent course is to regard optimality models as provisional guides to further empirical research and not necessarily as the key to deeper laws of nature.” It seems, then, that the semantic view of theories is more sensitive to the nature and limitations of optimality models than is the more traditional view of theories.

Ernst Mayr has argued that Darwinian theory discredited essentialist modes of thought and replaced them with what he has called “population thinking”. In this paper, I characterize essentialism as embodying a certain conception of how variation in nature is to be explained, and show how this conception was undermined by evolutionary theory. The Darwinian doctrine of evolutionary gradualism makes it impossible to say exactly where one species ends and another begins; such line-drawing problems are often taken to be the decisive reason for thinking that essentialism is untenable. However, according to the view of essentialism I suggest, this familiar objection is not fatal to essentialism. It is rather the essentialist's use of what I call the natural state model for explaining variation which clashes with evolutionary theory. This model implemented the essentialist's requirement that properties of populations be defined in terms of properties of member organisms. Requiring such constituent definitions is reductionistic in spirit; additionally, evolutionary theory shows that such definitions are not available, and, moreover, that they are not needed to legitimize population-level concepts. Population thinking involves the thesis that population concepts may be legitimized by showing their connections with each other, even when they are not reducible to concepts applying at lower levels of organization. In the paper, I develop these points by describing Aristotle's ideas on the origins of biological variation; they are a classic formulation of the natural state model. I also describe how the development of statistical ideas in the 19th century involved an abandoning of the natural state model.

This essay grows out of the conviction that recent work by psychologists studying human reasoning has important implications for a broad range of philosophical issues. To illustrate our thesis we focus on Nelson Goodman's elegant and influential attempt to “dissolve” the problem of induction. In the first section of the paper we sketch Goodman's account of what it is for a rule of inference to be justified. We then marshal empirical evidence indicating that, on Goodman's account of justification, patently invalid inferential rules turn out to be “justified.” We conclude that something is seriously wrong with Goodman's story about justification. In the second section we attempt to patch Goodman's account. The notion of epistemic authority and the social aspect of justification play central roles in the alternative account of justification that we propose.

A new problem about mathematical expectation: there exists a state of affairs S and options H and T such that in every element of one partition of S, the expectation of H exceeds that of T, while in every element of a different partition of S, the expectation of T exceeds that of H. This problem may be connected with questions about inference in the short and long run, and with questions about confidence intervals and fiducial probability.

Bayesian, Jeffrey and Field conditionals are compared and it is shown why the last two cannot be reduced to the first. Maximum relative entropy is used in two kinds of justification of the Field conditional and the dispensability of entropy principles in general is discussed.

Some features of physical science relevant for a discussion of physical explanation are mentioned. The D-N account of physical explanation is discussed, and it is seen to restrict the scope of explanation in physical science because it imposes the requirement that the explanandum must be deducible from the explanans. Analysis shows that an alternative view of scientific explanation, called the instance view, allows a wider range of physical explanations. The view is seen to be free from a certain class of counter examples to the D-N theory.

Although our theories are not precisely true, scientific realists contend that we should admit their objects into our ontology. One justification—offered by Sellars and Putnam—is that current theories belong to series that converge to ideally adequate theories. I consider the way the commitment to convergence reflects on the interpretation of lawlike claims. I argue that the distinction between lawlike and accidental generalizations depends on our cognitive interests and reflects our commitment to the direction of scientific progress. If the sciences disagree about the lawlikeness of some generalization(s), as an argument of Davidson's suggests, it follows from the interest relatively of lawlikeness that the laws of a science do not determine the essences of their objects. I conclude that this form of scientific realism provides no metaphysical support for essentialism.

In “Realism and Reason” Hilary Putnam has offered an apparently strong argument that the position of metaphysical realism provides an incoherent model of the relation of a correct scientific theory to the world. However, although Putnam's attack upon the notion of the “intended” interpretation of a scientific theory is sound, it is shown here that realism may be formulated in such a way that the realist need make no appeal to any “intended” interpretation of such a theory. Consequently, it can be shown that realism is immune to Putnam's criticism and that attempts at reformulating this criticism are not likely to meet with success.

It is argued that it is not sufficient to consider only the sentences included in the explanans and explanandum when determining whether they constitute an explanation, but these sentences must always be evaluated relative to a knowledge situation. The central criterion on an explanation is that the explanans in a non-trivial way increases the belief value of the explanandum, where the belief value of a sentence is determined from the given knowledge situation. The outlined theory of explanations is applied to some well-known examples and is also compared to other theories of explanation.

This paper defends the relevance of Taylor's (1964) critique of S-R behaviorism to Skinner's model of operant conditioning. In particular, it is argued against Ringen (1976) that the model of operant conditioning is a nonteleological variety of explanation. Operant conditioning is shown unable, on this account, to provide a parsimonious and predictive explanation of the behavior of higher level organisms. Finally, it is shown that the principle of operant conditioning implicitly assumes a teleological capacity, the admission of which renders the principle of operant conditioning superfluous.

The object of this paper is twofold: to show that resistance to scientific change on the part of scientists need signal neither irrationality nor the presence of extra-scientific influences; and to show how such resistance can be accommodated within a theory of rational choice. After considerations have been outlined suggesting that scientists cannot rationally resist new scientific theories unless theory choice is subjectivistic (section I), evidence is adduced favoring the contrary view (section II). In section III, a non-subjectivistic, non-relativistic conception of rational choice is proposed which recognizes the possibility of scientists' rationally resisting new scientific developments. Finally, in section IV, some minor misunderstandings concerning resistance are discussed.

Dutch Book arguments have been presented for static belief systems and for belief change by conditionalization. An argument is given here that a rule for belief change which under certain conditions violates probability kinematics will leave the agent open to a Dutch Book.

Basic research or fundamental research is distinct from both pure and applied research, in that it is pure research with expected useful results. The existence of basic or fundamental research is problematic, at least for both inductivists and instrumentalists, but also for Popper. Assuming scientific research to be the search for explanatory conjectures and for refutations, and assuming technology to be the search of conjectures and some corroborations, we can easily place basic or fundamental research between science and technology as a part of their overlap. As a bonus, the present view of basic or fundamental research as an overlap explains the specific hardship basic research workers encounter.

The so-called post-Wittgensteinian Oxford philosophers are often criticized not only for failing to provide for the causal explanation of human behavior and psychological states, but also for failing to recognize that psychological explanations require appeal to sub-personal or molecular processes. Three strategies accommodating this criticism appear in so-called homunculus theories and include: (1) that the sub-systems be assigned intentional or informational content purely heuristically; (2) that the intentional or informational content of molar states be analyzed without remainder in terms of molecular processing; (3) that the entire or salient range of mental or informational molar states be accessible at the molecular level, or vice versa. Option (2) proves to be the most radical and is favored by Dennett. (1) relevantly requires a reduction of the intentional. (3) is illustrated in various ways by the views of Freud, Chomsky, Fodor. (2) is shown to depend on (1) or to be idle; and (3) embraces at least in part an appeal to molar-level explanation. The argument developed attempts to show the sense in which discourse about molar and molecular-level phenomena in the psychological context is fundamentally different from macroscopic and microtheoretical-level discourse about physical phenomena. The conclusion drawn is that neither a molar nor a sub-personal level theory is suitably explanatory in the psychological sense: a psychological theory is committed rather to a set of sub-personal components of such systems, that serve to explain molar phenomena.

This paper studies the theory of uniqueness of scales of measurement, and in particular, the theory of meaningfulness of statements using scales. The paper comments on the general theory of meaningfulness adopted by Luce in connection with his work on dimensionally invariant numerical laws. It comments on Luce's generalization of the concept of meaningfulness of a statement involving scales to a concept of meaningfulness of an arbitrary relation relative to the defining relations in a relational structure. It is argued that in studying the concept of meaningfulness, it is necessary to consider invariance under endomorphisms, not just automorphisms. The difference between the endomorphism and automorphism concepts of meaningfulness is studied. Luce's primary result, that automorphism meaningfulness is preserved under isomorphism, is extended to the result that endomorphism meaningfulness is preserved under homomorphism.