Some of the most imaginative analyses in contemporary science have been fostered by the paradox of irreversibility. Rendered as a question the paradox reads: How can the anisotropic macrophysical behavior of a system of molecules be reconciled with the underlying reversible molecular model? Attempts to resolve and dissolve the paradox have appealed to large numbers of particles, jammed correlations, unseen perturbations, hidden variables or constraints, uncertainty principles, averaging procedures (e.g., coarse graining and time smoothing), stochastic flaws, cosmological origins, etc.

While acknowledging these efforts as important articulations of basic ideas of statistical mechanics, we question their relevance to irreversibility as it occurs in nature. It seems to us that once the emergence of the phenomenon of equilibrium is understood in terms of molecular dynamics, the macroscopic appearance of irreversibility can also be understood in terms of the frequency of forced withdrawals from young equilibria. We believe that the paradox of irreversibility can be resolved in a simple, logically clear, and aesthetically pleasing manner.

Several evolutionary biologists have used a parsimony argument to argue that the single gene is the unit of selection. Since all evolution by natural selection can be represented in terms of selection coefficients attaching to single genes, it is, they say, “more parsimonious” to think that all selection is selection for or against single genes. We examine the limitations of this genic point of view, and then relate our criticisms to a broader view of the role of causal concepts and the dangers of reification in science.

Through a study of a sophisticated contemporary scientific experiment, it is shown how and why use of the term ‘observation’ in reference to that experiment departs from ordinary and philosophical usages which associate observation epistemically with perception. The role of “background information” is examined, and general conclusions are arrived at regarding the use of descriptive language in and in talking about science. These conclusions bring out the reasoning by which science builds on what it has learned, and, further, how that process of building consists not only in adding to our substantive knowledge, but also in increasing our ability to learn about nature, by extending our ability to observe it in new ways. The argument of this paper is thus a step toward understanding how it is that all our knowledge of nature rests on observation.

Popper distinguishes the problems of theoretical and pragmatic preference between rival theories, but he claims that there is a common non-inductive solution to both of them, viz. the “best-tested theory”, or the theory with the highest degree of corroboration. He further suggests that the degrees of corroboration serve as indicators of verisimilitude. One may therefore raise the question whether the recent theory of verisimilitude gives a general non-inductive solution to the problem of theoretical preference. This paper argues that this is not the case: the theory of verisimilitude is applicable to this problem if and only if there is an independent solution to the problem of induction. Moreover, the solutions to the theoretical and pragmatic problems of preference coincide only in some special cases.

While there has been general agreement among modern philosophers of science that a purely a priori method is inappropriate to the task of establishing a theory of science, there has, unfortunately, been little comparable agreement regarding the method that is appropriate. I try to lay the foundations for such agreement. I first set out reasons for a purely empirical method for establishing a theory of science, and defend such a method against charges raised by Giere. I then develop some very basic criteria for the evaluation of alternative empirical methods for establishing a theory of science, and use these criteria to evaluate the two such methods that have dominated philosophic discussion in recent years—those of Lakatos and Laudan. I end by defending a revised version of Lakatos’ proposal.

This paper treats some of the issues raised by Putnam's discussion of, and claims for, quantum logic, specifically: that its proposal is a response to experimental difficulties; that it is a reasonable replacement for classical logic because its connectives retain their classical meanings, and because it can be derived as a logic of tests. We argue that the first claim is wrong (1), and that while conjunction and disjunction can be considered to retain their classical meanings, negation crucially does not. The argument is conducted via a thorough analysis of how the meet, join and complementation operations are defined in the relevant logical structures, respectively Boolean- and ortholattices (3). Since Putnam wishes to reinstate a realist interpretation of quantum mechanics, we ask how quantum logic can be a logic of realism. We show that it certainly cannot be a logic of bivalence realism (i.e., of truth and falsity), although it is consistent with some form of ontological realism (4). Finally, we show that while a reasonable explication of the idealized notion of test yields interesting mathematical structure, it by no means yields the rich ortholattice structure which Putnam (following Finkelstein) seeks.

This paper examines the “causal theory of reference”, according to which science aims at the discovery of “essences” which are the objects of reference of natural kind terms (among others). This theory has been advanced as an alternative to traditional views of “meaning”, on which a number of philosophical accounts of science have relied, and which have been criticized earlier by the present author. However, this newer theory of reference is shown to be equally subject to fatal internal difficulties, and to be incompatible with actual science as well. Indeed, it rests on assumptions which it shares with the purportedly opposing theory of meaning. Behind those common assumptions is the supposition that the nature of science can be illuminated by an examination of alleged necessities of language which are independent of the results and methods of scientific inquiry. An alternative view of science is proposed, according to which the goals and language of science develop as integral parts of the process of demarcating science from non-science, a process in which the notion of a “reason” gradually assumes a decisive role. On this view, the comparability, competition, and development of scientific ideas are understood without reliance on either common “meanings” or common “references” as fundamental tools of analysis.

If p(x1, …, xn) and q(x1 …, xn) are two logically equivalent propositions then p(π(x1), …, π(xn)) and q(π(x1), …,π(xn)) are also logically equivalent where π is an arbitrary permutation of the elementary constituents x1, …, xn. In Quantum Logic the invariance of logical equivalences breaks down. It is proved that the distribution rules of classical logic are in fact equivalent to the meta-linguistic rule of universal substitution and that the more restrictive structure of the substitution group of Quantum Logic prevents us from defining truth in a classical fashion. These observations lead to a more profound understanding of the Logic of Quantum Mechanics and of the role that symmetry principles play in that theory.

… Its decisive difference in comparison to the Classical-Model is the fact that gratings in vector-space defy superposition.

—Hermann Weyl (1949)

Although on opposite sides of the logic of discovery debate, Laudan and Simon share a thesis of divorce between discovery (invention) and justification (appraisal); but unlike some other authors, they do not base their respective versions of the divorce-thesis on the empirical/logical distinction. Laudan argues that, in contemporary science, invention is irrelevant to appraisal, and that this irrelevance renders epistemically pointless the inventionist program. Simon uses his divorce-thesis to defend his account of invention, which he claims to be non-inductive—so evading the problem of induction. Underlying both authors' positions are inadequate conceptions of inductive inference. Laudan here ignores the role in contemporary science of plausibility arguments, which provide a crucial link between invention and appraisal, and thence an epistemic rationale for inventionism. Simon's account of invention does covertly call upon inductive principles from the context of appraisal, and this is what gives his program epistemic import; otherwise he would be vulnerable to Laudan's “no rationale” critique. The tensions in both authors reveal the falsity of the divorce-thesis, and the essential function of induction in both appraisal and invention of hypotheses.

The aim of this paper is to describe a methodology for revising logical principles in the light of empirical psychological findings. Historical philosophy of science and wide reflective equilibrium in ethics are considered as providing possible models for arguing from the descriptive to the normative. Neither is adequate for the psychology/logic case, and a new model is constructed, employing criteria for evaluating inferential systems. Once we have such criteria, the notion of reflective equilibrium becomes redundant.

One way in which philosophy of science can perform a valuable normative function for science is by showing characteristic errors made in scientific research programs and proposing ways in which such errors can be avoided or corrected. This paper examines two errors that have commonly plagued research in biology and psychology: 1) functional localization errors that arise when parts of a complex system are assigned functions which these parts are not themselves able to perform, and 2) vacuous functional explanations in which one provides an analysis that does account for the inputs and outputs of a system but does not employ the same set of functions to produce this output as does the natural system. These two kinds of error usually arise when researchers limit their investigation to one type of evidence. Historically, correction of these errors has awaited researchers who have employed the opposite type of evidence. This paper explores the tendency to commit these errors by examining examples from historical and contemporary science and proposes a dialectical process through which researchers can avoid or correct such errors in the future.

In the correspondence with Clarke, Leibniz proposes to construe physical theory in terms of physical (spatio-temporal) relations between physical objects, thus avoiding incorporation of infinite totalities of abstract entities (such as Newtonian space) in physical ontology. It has generally been felt that this proposal cannot be carried out.

I demonstrate an equivalence between formulations postulating space-time as an infinite totality and formulations allowing only possible spatio-temporal relations of physical (point -) objects. The resulting rigorous formulations of physical theory may be seen to follow Leibniz’ suggestion quite closely. On the other hand, physical assumptions implicit in the postulation of space-time totalities are made explicit in the reconstruction of the space-time versions from the physical-relation versions.

Wilfrid Sellars has proposed a materialist account of sensation which relies in part on the postulation of special kinds of individuals. This postulational strategy appears to be analogous to the one that introduces such entities as electrons. After setting out Sellars' account, I focus on his application of the postulational strategy. I argue that this application requires the discovery of new effects for familiar properties; that this kind of discovery is disanalogous to what postulation usually does; and that this kind of discovery cannot really be arrived at by postulation. I conclude that Sellars has not provided a successful, materialist account of sensation.

Friedman and Putnam have argued (Friedman and Putnam 1978) that the quantum logical interpretation of quantum mechanics gives us an explanation of interference that the Copenhagen interpretation cannot supply without invoking an additional ad hoc principle, the projection postulate. I show that it is possible to define a notion of equivalence of experimental arrangements relative to a pure state φ, or (correspondingly) equivalence of Boolean subalgebras in the partial Boolean algebra of projection operators of a system, which plays a role in the Copenhagen explanation of interference analogous to the role played by the material equivalence, given φ, of certain propositions in the Friedman-Putnam quantum logical analysis. I also show that the quantum logical interpretation and the Copenhagen interpretation are equally capable of avoiding the paradoxical conclusion of the Einstein-Podolsky-Rosen argument (Einstein, Podolsky, and Rosen 1935). Thus, neither interference phenomena nor the correlations between separated systems provide a test case for distinguishing between the relative acceptability of the Copenhagen interpretation and the quantum logical interpretation as explanations of quantum effects.

Bell's Theorem is proved for locality and conservation formulated in terms of subjunctive conditionals with chance consequents, rather than the usual conditional probability formulation. This brings into sharp focus the minimal counterfactual assumptions needed for Bell's theorem.

This paper examines the view that ordinary particulars are complexes of universals. Russell's attempt to develop such a theory is articulated and defended against some common misinterpretations and unfounded criticisms in Section I. The next two sections address an argument which is standardly cited as the primary problem confronting the theory: (1) it is committed to the necessary truth of the principle of the identity of indiscernibles; (2) the principle is not necessarily true. It is argued in Section II that a proponent of the theory need not accept (1) and an argument against (2) is presented in Section III. The final section attempts to show that Russell's theory ultimately fails because of inadequacies in its treatment of space and time. The paper closes with a suggestion for remedying this difficulty.

This paper discusses different interpretations of probability in relation to determinism. It is argued that both objective and subjective views on probability can be compatible with deterministic as well as indeterministic situations. The possibility of a conceptual independence between probability and determinism is argued to hold on a general level. The subsequent philosophical analysis of recent advances in classical statistical mechanics (ergodic theory) is of independent interest, but also adds weight to the claim that it is possible to justify an objective interpretation of probabilities in a theory having as a basis the paradigmatically deterministic theory of classical mechanics.

Aristotle's rule of proportions of the factors of motion, presented in VII 5 of the Physics, characterizes Aristotelian force. Observing that the locomotion to which Aristotle applied the Rule is the motion produced by manual labor, I develop an interpretation of the factors of motion that reveals that Aristotelian force is Newtonian power. An alternate interpretation of the Rule by Toulmin and Goodfield implicitly identifies Aristotelian force with Newtonian force. In order to account for the absence of an acceleration in the rate of forced motion, they incorporate into the Rule the medium's resistance to motion due to viscosity as an additional factor. The resulting interpretations of the original factors of motion lose the exactness the power interpretation grants them. The constant rate of forced motion follows immediately from the power interpretation. It is also compatible with the Rule's description of the motion that is produced by the sum of forces.

In a recent paper, Michael Friedman and Hilary Putnam argued that the Lüders rule is ad hoc from the point of view of the Copenhagen interpretation but that it receives a natural explanation within realist quantum logic as a probability conditionalization rule. Geoffrey Hellman maintains that quantum logic cannot give a non-circular explanation of the rule, while Jeffrey Bub argues that the rule is not ad hoc within the Copenhagen interpretation. As I see it, all four are wrong. Given that there is to be a projection postulate, there are at least two natural arguments which the Copenhagen advocate can offer on behalf of the Lüders rule, contrary to Friedman and Putnam. However, the argument which Bub offers is not a good one. At the same time, contrary to Hellman, quantum logic really does provide an explanation of the Lüders rule, and one which is superior to that of the Copenhagen account, since it provides an understanding of why there should be a projection postulate at all.